refactor : 重构网络下载模块

新增通用下载接口，扩展了默认的Unity引擎下载器

Assets/YooAsset/CHANGELOG.md

@@ -2,6 +2,57 @@
 
 All notable changes to this package will be documented in this file.
 
+## [2.3.18] - 2025-12-04
+
+### Fixed
+
+- (#676) 修复了UniTask扩展包的编译报错。
+- (#684) 修复了资源配置窗口Group列表数量过多的时候，添加和删除按钮会变小的问题。
+- (#700) [**严重**] 修复了小游戏扩展库的下载器再失败后重试逻辑不起效的问题。
+
+### Added
+
+- (#683) 新增了内置文件系统类初始化参数：UNPACK_FILE_SYSTEM_ROOT
+
+  ```csharp
+  class FileSystemParametersDefine
+  {
+      // 指定解压文件的根目录
+      public const string UNPACK_FILE_SYSTEM_ROOT = "UNPACK_FILE_SYSTEM_ROOT";
+  }
+  ```
+
+- (#682) 原生文件构建管线新增构建参数：IncludePathInHash
+
+  ```csharp
+  class RawFileBuildParameters : BuildParameters
+  {
+      /// <summary>
+      /// 文件哈希值计算包含路径信息
+      /// </summary>
+      public bool IncludePathInHash = false;
+  }
+  ```
+
+- (#671) 新增扩展工具，可以生成空的包裹内置资源目录文件。
+
+  ```csharp
+  public class CreateEmptyCatalogWindow : EditorWindow
+  ```
+
+- (#694) 新增资源清理方式：ClearBundleFilesByLocations
+
+  ```csharp
+  public enum EFileClearMode
+  {
+      /// <summary>
+      /// 清理指定地址的文件
+      /// 说明：需要指定参数，可选：string, string[], List<string>
+      /// </summary>
+      ClearBundleFilesByLocations,
+  }
+  ```
+
 ## [2.3.17] - 2025-10-30
 
 **非常重要**：修复了#627优化导致的资源清单CRC值为空的问题。
@@ -16,10 +67,6 @@ All notable changes to this package will be documented in this file.
 
 影响范围：所有版本！
 
-### Improvements
-
-- 重构并统一了资源清单的反序列化逻辑。
-
 ### Fixed
 
 - (#645) 修复了着色器变种收集工具，在极端情况下变种收集不完整的问题。
@@ -29,6 +76,7 @@ All notable changes to this package will be documented in this file.
 
 ### Improvements
 
+- 重构并统一了资源清单的反序列化逻辑。
 - (#650) 解决互相依赖的资源包无法卸载的问题。需要开启宏定义：YOOASSET_EXPERIMENTAL
 - (#655) 优化了初始化的时候，缓存文件搜索效率。安卓平台性能提升1倍，IOS平台性能提升3倍。
 

Assets/YooAsset/Editor/AssetArtReporter/AssetArtReporterWindow.cs

@@ -261,14 +261,14 @@ namespace YooAsset.Editor
             catch (System.Exception e)
             {
                 _reportCombiner = null;
-                _titleLabel.text = "导入报告失败！";
+                _titleLabel.text = "Failed to import report!";
                 _descLabel.text = e.Message;
                 UnityEngine.Debug.LogError(e.StackTrace);
             }
         }
         private void FixAllBtn_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", "修复全部资源（排除白名单和隐藏元素）", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", "Fix all resources (excluding whitelist and hidden elements)", "Yes", "No"))
             {
                 if (_reportCombiner != null)
                     _reportCombiner.FixAll();
@@ -276,7 +276,7 @@ namespace YooAsset.Editor
         }
         private void FixSelectBtn_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", "修复勾选资源（包含白名单和隐藏元素）", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", "Fix selected resources (including whitelist and hidden elements)", "Yes", "No"))
             {
                 if (_reportCombiner != null)
                     _reportCombiner.FixSelect();
@@ -302,7 +302,7 @@ namespace YooAsset.Editor
         }
         private void ExportFilesBtn_clicked()
         {
-            string selectFolderPath = EditorUtility.OpenFolderPanel("导入所有选中资源", EditorTools.GetProjectPath(), string.Empty);
+            string selectFolderPath = EditorUtility.OpenFolderPanel("Export all selected resources", EditorTools.GetProjectPath(), string.Empty);
             if (string.IsNullOrEmpty(selectFolderPath) == false)
             {
                 if (_reportCombiner != null)

Assets/YooAsset/Editor/AssetArtScanner/AssetArtScannerWindow.cs

@@ -240,7 +240,7 @@ namespace YooAsset.Editor
         }
         private void ScanAllBtn_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", $"开始全面扫描！", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", $"Start full scan!", "Yes", "No"))
             {
                 string searchKeyWord = _scannerSearchField.value;
                 AssetArtScannerSettingData.ScanAll(searchKeyWord);
@@ -248,7 +248,7 @@ namespace YooAsset.Editor
             }
             else
             {
-                Debug.LogWarning("全面扫描已经取消");
+                Debug.LogWarning("Full scan has been canceled.");
             }
         }
         private void ScanBtn_clicked()

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/BaseTasks/TaskUpdateBundleInfo.cs

@@ -44,9 +44,9 @@ namespace YooAsset.Editor
             {
                 bundleInfo.PackageUnityHash = GetUnityHash(bundleInfo, context);
                 bundleInfo.PackageUnityCRC = GetUnityCRC(bundleInfo, context);
-                bundleInfo.PackageFileHash = GetBundleFileHash(bundleInfo, buildParametersContext);
-                bundleInfo.PackageFileCRC = GetBundleFileCRC(bundleInfo, buildParametersContext);
-                bundleInfo.PackageFileSize = GetBundleFileSize(bundleInfo, buildParametersContext);
+                bundleInfo.PackageFileHash = GetBundleFileHash(bundleInfo, context);
+                bundleInfo.PackageFileCRC = GetBundleFileCRC(bundleInfo, context);
+                bundleInfo.PackageFileSize = GetBundleFileSize(bundleInfo, context);
             }
 
             // 4.更新补丁包输出的文件路径
@@ -62,8 +62,8 @@ namespace YooAsset.Editor
 
         protected abstract string GetUnityHash(BuildBundleInfo bundleInfo, BuildContext context);
         protected abstract uint GetUnityCRC(BuildBundleInfo bundleInfo, BuildContext context);
-        protected abstract string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext);
-        protected abstract uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext);
-        protected abstract long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext);
+        protected abstract string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildContext context);
+        protected abstract uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildContext context);
+        protected abstract long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildContext context);
     }
 }

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/BuiltinBuildPipeline/BuildTasks/TaskUpdateBundleInfo_BBP.cs

@@ -40,17 +40,17 @@ namespace YooAsset.Editor
                 throw new Exception(message);
             }
         }
-        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return HashUtility.FileMD5(filePath);
         }
-        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return HashUtility.FileCRC32Value(filePath);
         }
-        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return FileUtility.GetFileSize(filePath);

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/EditorSimulateBuildPipeline/BuildTasks/TaskUpdateBundleInfo_ESBP.cs

@@ -19,16 +19,16 @@ namespace YooAsset.Editor
         {
             return 0;
         }
-        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return GetFilePathTempHash(filePath);
         }
-        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildContext context)
         {
             return 0;
         }
-        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildContext context)
         {
             return GetBundleTempSize(bundleInfo);
         }

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/RawFileBuildPipeline/BuildTasks/TaskUpdateBundleInfo_RFBP.cs

@@ -15,27 +15,55 @@ namespace YooAsset.Editor
 
         protected override string GetUnityHash(BuildBundleInfo bundleInfo, BuildContext context)
         {
-            string filePath = bundleInfo.PackageSourceFilePath;
-            return HashUtility.FileMD5(filePath);
+            var buildParametersContext = context.GetContextObject<BuildParametersContext>();
+            var rawFileBuildParameters = buildParametersContext.Parameters as RawFileBuildParameters;
+            if (rawFileBuildParameters.IncludePathInHash)
+            {
+                string filePath = bundleInfo.PackageSourceFilePath;
+                return GetFileMD5IncludePath(filePath);
+            }
+            else
+            {
+                string filePath = bundleInfo.PackageSourceFilePath;
+                return HashUtility.FileMD5(filePath);
+            }
         }
         protected override uint GetUnityCRC(BuildBundleInfo bundleInfo, BuildContext context)
         {
             return 0;
         }
-        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildContext context)
         {
-            string filePath = bundleInfo.PackageSourceFilePath;
-            return HashUtility.FileMD5(filePath);
+            var buildParametersContext = context.GetContextObject<BuildParametersContext>();
+            var rawFileBuildParameters = buildParametersContext.Parameters as RawFileBuildParameters;
+            if (rawFileBuildParameters.IncludePathInHash)
+            {
+                string filePath = bundleInfo.PackageSourceFilePath;
+                return GetFileMD5IncludePath(filePath);
+            }
+            else
+            {
+                string filePath = bundleInfo.PackageSourceFilePath;
+                return HashUtility.FileMD5(filePath);
+            }
         }
-        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return HashUtility.FileCRC32Value(filePath);
         }
-        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return FileUtility.GetFileSize(filePath);
         }
+
+        private string GetFileMD5IncludePath(string filePath)
+        {
+            string pathHash = HashUtility.StringMD5(filePath.ToLowerInvariant());
+            string contentHash = HashUtility.FileMD5(filePath);
+            string combined = pathHash + contentHash;
+            return HashUtility.StringMD5(combined);
+        }
     }
 }

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/RawFileBuildPipeline/RawFileBuildParameters.cs

@@ -6,5 +6,9 @@ namespace YooAsset.Editor
 {
     public class RawFileBuildParameters : BuildParameters
     {
+        /// <summary>
+        /// 文件哈希值计算包含路径信息
+        /// </summary>
+        public bool IncludePathInHash = false;
     }
 }

Assets/YooAsset/Editor/AssetBundleBuilder/BuildPipeline/ScriptableBuildPipeline/BuildTasks/TaskUpdateBundleInfo_SBP.cs

@@ -40,17 +40,17 @@ namespace YooAsset.Editor
                 throw new Exception(message);
             }
         }
-        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override string GetBundleFileHash(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return HashUtility.FileMD5(filePath);
         }
-        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override uint GetBundleFileCRC(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return HashUtility.FileCRC32Value(filePath);
         }
-        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildParametersContext buildParametersContext)
+        protected override long GetBundleFileSize(BuildBundleInfo bundleInfo, BuildContext context)
         {
             string filePath = bundleInfo.PackageSourceFilePath;
             return FileUtility.GetFileSize(filePath);

Assets/YooAsset/Editor/AssetBundleBuilder/VisualViewers/BuiltinBuildPipeline/BuiltinBuildPipelineViewer.cs

@@ -82,14 +82,14 @@ namespace YooAsset.Editor
         }
         private void BuildButton_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", $"开始构建资源包[{PackageName}]！", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", $"Start building resource package [{PackageName}]!", "Yes", "No"))
             {
                 EditorTools.ClearUnityConsole();
                 EditorApplication.delayCall += ExecuteBuild;
             }
             else
             {
-                Debug.LogWarning("[Build] 打包已经取消");
+                Debug.LogWarning("[Build] Packaging has been canceled.");
             }
         }
 

Assets/YooAsset/Editor/AssetBundleBuilder/VisualViewers/EditorSimulateBuildpipeline/EditorSimulateBuildPipelineViewer.cs

@@ -42,14 +42,14 @@ namespace YooAsset.Editor
         }
         private void BuildButton_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", $"开始构建资源包[{PackageName}]！", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", $"Start building resource package [{PackageName}]!", "Yes", "No"))
             {
                 EditorTools.ClearUnityConsole();
                 EditorApplication.delayCall += ExecuteBuild;
             }
             else
             {
-                Debug.LogWarning("[Build] 打包已经取消");
+                Debug.LogWarning("[Build] Packaging has been canceled.");
             }
         }
 

Assets/YooAsset/Editor/AssetBundleBuilder/VisualViewers/RawfileBuildpipeline/RawfileBuildPipelineViewer.cs

@@ -77,14 +77,14 @@ namespace YooAsset.Editor
         }
         private void BuildButton_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", $"开始构建资源包[{PackageName}]！", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", $"Start building resource package [{PackageName}]!", "Yes", "No"))
             {
                 EditorTools.ClearUnityConsole();
                 EditorApplication.delayCall += ExecuteBuild;
             }
             else
             {
-                Debug.LogWarning("[Build] 打包已经取消");
+                Debug.LogWarning("[Build] Packaging has been canceled.");
             }
         }
 

Assets/YooAsset/Editor/AssetBundleBuilder/VisualViewers/ScriptableBuildPipeline/ScriptableBuildPipelineViewer.cs

@@ -82,14 +82,14 @@ namespace YooAsset.Editor
         }
         private void BuildButton_clicked()
         {
-            if (EditorUtility.DisplayDialog("提示", $"开始构建资源包[{PackageName}]！", "Yes", "No"))
+            if (EditorUtility.DisplayDialog("Info", $"Start building resource package [{PackageName}]!", "Yes", "No"))
             {
                 EditorTools.ClearUnityConsole();
                 EditorApplication.delayCall += ExecuteBuild;
             }
             else
             {
-                Debug.LogWarning("[Build] 打包已经取消");
+                Debug.LogWarning("[Build] Packaging has been canceled.");
             }
         }
 

Assets/YooAsset/Editor/AssetBundleCollector/AssetBundleCollectorWindow.uxml

@@ -30,7 +30,7 @@
         <ui:VisualElement name="PackageContainer" style="width: 200px; flex-grow: 0; background-color: rgb(67, 67, 67); border-left-width: 5px; border-right-width: 5px; border-top-width: 5px; border-bottom-width: 5px;">
             <ui:Label text="Packages" display-tooltip-when-elided="true" name="PackageTitle" style="background-color: rgb(89, 89, 89); -unity-text-align: upper-center; -unity-font-style: bold; border-left-width: 5px; border-right-width: 5px; border-top-width: 5px; border-bottom-width: 5px; font-size: 12px;" />
             <ui:ListView focusable="true" name="PackageListView" item-height="20" virtualization-method="DynamicHeight" reorderable="true" reorder-mode="Animated" style="flex-grow: 1;" />
-            <ui:VisualElement name="PackageAddContainer" style="height: 20px; flex-direction: row; justify-content: center;">
+            <ui:VisualElement name="PackageAddContainer" style="height: 20px; flex-direction: row; justify-content: center; flex-shrink: 0;">
                 <ui:Button text=" - " display-tooltip-when-elided="true" name="RemoveBtn" />
                 <ui:Button text=" + " display-tooltip-when-elided="true" name="AddBtn" />
             </ui:VisualElement>
@@ -40,7 +40,7 @@
             <ui:TextField picking-mode="Ignore" label="Package Name" name="PackageName" style="flex-direction: column;" />
             <ui:TextField picking-mode="Ignore" label="Package Desc" name="PackageDesc" style="flex-direction: column;" />
             <ui:ListView focusable="true" name="GroupListView" item-height="20" virtualization-method="DynamicHeight" reorderable="true" reorder-mode="Animated" style="flex-grow: 1;" />
-            <ui:VisualElement name="GroupAddContainer" style="height: 20px; flex-direction: row; justify-content: center;">
+            <ui:VisualElement name="GroupAddContainer" style="height: 20px; flex-direction: row; justify-content: center; flex-shrink: 0;">
                 <ui:Button text=" - " display-tooltip-when-elided="true" name="RemoveBtn" />
                 <ui:Button text=" + " display-tooltip-when-elided="true" name="AddBtn" />
             </ui:VisualElement>

Assets/YooAsset/Editor/AssetBundleCollector/AssetDependencyDatabase.cs

@@ -88,8 +88,8 @@ namespace YooAsset.Editor
             }
             catch (Exception ex)
             {
-                ClearDatabase(true);
                 Debug.LogError($"Failed to load cache database : {ex.Message}");
+                ClearDatabase(true);
             }
             finally
             {
@@ -169,7 +169,8 @@ namespace YooAsset.Editor
                     File.Delete(_databaseFilePath);
             }
 
-            _database.Clear();
+            if (_database != null)
+                _database.Clear();
         }
 
         /// <summary>

Assets/YooAsset/Editor/EditorDefine.cs

@@ -41,6 +41,8 @@ namespace YooAsset.Editor
         Texture,
         RenderTexture,
         VideoClip,
+        PlayableAsset,
+        TimelineAsset
     }
 
     /// <summary>

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadBackend.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: a8f060786f8775b4a82cc3f55d9135e2
+guid: bb70e2274ce5a5d419cfbd7212efdf4a
 folderAsset: yes
 DefaultImporter:
   externalObjects: {}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadBackend/UnityWebRequestBackend.cs

@@ -0,0 +1,110 @@
+using System;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest 下载后台
+    /// </summary>
+    /// <remarks>
+    /// 基于 Unity 内置 UnityWebRequest 实现的下载后台。
+    /// 支持自定义 UnityWebRequest 创建方式，例如添加证书验证、代理设置等。
+    /// </remarks>
+    internal sealed class UnityWebRequestBackend : IDownloadBackend
+    {
+        private readonly UnityWebRequestDelegate _webRequestCreator;
+
+        /// <summary>
+        /// 后端名称
+        /// </summary>
+        public string Name
+        {
+            get { return nameof(UnityWebRequestBackend); }
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest 下载后端（使用默认创建方式）
+        /// </summary>
+        public UnityWebRequestBackend() : this(null)
+        {
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest 下载后端
+        /// </summary>
+        /// <param name="webRequestCreator">
+        /// 自定义 UnityWebRequest 创建委托（可选）。
+        /// 如果为 null，则使用默认的 UnityWebRequest 构造方式。
+        /// </param>
+        public UnityWebRequestBackend(UnityWebRequestDelegate webRequestCreator)
+        {
+            _webRequestCreator = webRequestCreator;
+        }
+
+        /// <summary>
+        /// 驱动更新
+        /// </summary>
+        /// <remarks>
+        /// UnityWebRequest 由 Unity 引擎自动驱动，无需额外更新。
+        /// </remarks>
+        public void Update()
+        {
+        }
+
+        /// <summary>
+        /// 释放资源
+        /// </summary>
+        public void Dispose()
+        {
+            // 无需释放资源
+        }
+
+        /// <summary>
+        /// 创建 HEAD 请求
+        /// </summary>
+        public IDownloadHeadRequest CreateHeadRequest(DownloadDataRequestArgs args)
+        {
+            return new UnityWebRequestHeadDownloader(args, _webRequestCreator);
+        }
+
+        /// <summary>
+        /// 创建文件下载请求
+        /// </summary>
+        public IDownloadFileRequest CreateFileRequest(DownloadFileRequestArgs args)
+        {
+            return new UnityWebRequestFileDownloader(args, _webRequestCreator);
+        }
+
+        /// <summary>
+        /// 创建字节下载请求
+        /// </summary>
+        public IDownloadBytesRequest CreateBytesRequest(DownloadDataRequestArgs args)
+        {
+            return new UnityWebRequestBytesDownloader(args, _webRequestCreator);
+        }
+
+        /// <summary>
+        /// 创建文本下载请求
+        /// </summary>
+        public IDownloadTextRequest CreateTextRequest(DownloadDataRequestArgs args)
+        {
+            return new UnityWebRequestTextDownloader(args, _webRequestCreator);
+        }
+
+        /// <summary>
+        /// 创建 AssetBundle 下载请求
+        /// </summary>
+        public IDownloadAssetBundleRequest CreateAssetBundleRequest(DownloadAssetBundleRequestArgs args)
+        {
+            return new UnityWebRequestAssetBundleDownloader(args, _webRequestCreator);
+        }
+
+        /// <summary>
+        /// 创建模拟下载请求
+        /// </summary>
+        public IDownloadFileRequest CreateSimulateRequest(DownloadSimulateRequestArgs args)
+        {
+            return new VirtualFileDownloader(args);
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadBackend/UnityWebRequestBackend.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 932e4c4574244dac8c27d9ddc156f8ff
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest.meta

@@ -0,0 +1,8 @@
+fileFormatVersion: 2
+guid: 1d30af9086de4fb282c2cdd3d26244c0
+folderAsset: yes
+DefaultImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestAssetBundleDownloader.cs

@@ -0,0 +1,92 @@
+using System;
+using UnityEngine;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest AssetBundle 下载器
+    /// </summary>
+    /// <remarks>
+    /// 下载并加载 Unity AssetBundle 资源包。
+    /// 支持 Unity 内置缓存机制和 CRC 校验。
+    /// </remarks>
+    internal sealed class UnityWebRequestAssetBundleDownloader : UnityWebRequestDownloaderBase, IDownloadAssetBundleRequest
+    {
+        private readonly DownloadAssetBundleRequestArgs _args;
+        private DownloadHandlerAssetBundle _downloadHandler;
+
+        /// <summary>
+        /// 下载结果（AssetBundle 对象）
+        /// </summary>
+        public AssetBundle Result { get; private set; }
+
+        /// <summary>
+        /// 构造 AssetBundle 下载器
+        /// </summary>
+        /// <param name="args">AssetBundle 下载参数</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        public UnityWebRequestAssetBundleDownloader(DownloadAssetBundleRequestArgs args, UnityWebRequestDelegate webRequestCreator)
+            : base(args.URL, webRequestCreator)
+        {
+            _args = args;
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest
+        /// </summary>
+        protected override void CreateWebRequest()
+        {
+            _downloadHandler = CreateAssetBundleDownloadHandler();
+            _webRequest = CreateUnityWebRequestGet(URL);
+            _webRequest.downloadHandler = _downloadHandler;
+            _webRequest.disposeDownloadHandlerOnDispose = true;
+            ApplyRequestOptions(_args.Timeout, _args.WatchdogTime, _args.Headers);
+        }
+
+        /// <summary>
+        /// 请求成功时的回调
+        /// </summary>
+        protected override void OnRequestSucceed()
+        {
+            AssetBundle assetBundle = _downloadHandler.assetBundle;
+            if (assetBundle == null)
+            {
+                Status = EDownloadRequestStatus.Failed;
+                Error = $"[{GetType().Name}] URL: {URL} - AssetBundle object is null";
+            }
+            else
+            {
+                Result = assetBundle;
+            }
+        }
+
+        /// <summary>
+        /// 创建 AssetBundle 下载处理器
+        /// </summary>
+        private DownloadHandlerAssetBundle CreateAssetBundleDownloadHandler()
+        {
+            DownloadHandlerAssetBundle handler;
+
+            if (_args.DisableUnityWebCache)
+            {
+                // 禁用 Unity 缓存
+                handler = new DownloadHandlerAssetBundle(URL, _args.UnityCRC);
+            }
+            else
+            {
+                // 使用 Unity 缓存（需要 FileHash）
+                // The file hash defining the version of the asset bundle.
+                Hash128 fileHash = Hash128.Parse(_args.FileHash);
+                handler = new DownloadHandlerAssetBundle(URL, fileHash, _args.UnityCRC);
+            }
+
+#if UNITY_2020_3_OR_NEWER
+            // 禁用自动加载，允许手动控制加载时机
+            handler.autoLoadAssetBundle = false;
+#endif
+
+            return handler;
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestAssetBundleDownloader.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: e01cc308d7179a34281087fafe455b42
+guid: 6f635344c08e2b04295a108c2bcc6a40
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestBytesDownloader.cs

@@ -0,0 +1,61 @@
+using System;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest 字节下载器
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容保存到内存中的字节数组。
+    /// </remarks>
+    internal sealed class UnityWebRequestBytesDownloader : UnityWebRequestDownloaderBase, IDownloadBytesRequest
+    {
+        private readonly DownloadDataRequestArgs _args;
+
+        /// <summary>
+        /// 下载结果（字节数组）
+        /// </summary>
+        public byte[] Result { get; private set; }
+
+        /// <summary>
+        /// 构造字节数组下载器
+        /// </summary>
+        /// <param name="args">数据下载参数</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        public UnityWebRequestBytesDownloader(DownloadDataRequestArgs args, UnityWebRequestDelegate webRequestCreator)
+            : base(args.URL, webRequestCreator)
+        {
+            _args = args;
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest
+        /// </summary>
+        protected override void CreateWebRequest()
+        {
+            var handler = new DownloadHandlerBuffer();
+            _webRequest = CreateUnityWebRequestGet(URL);
+            _webRequest.downloadHandler = handler;
+            _webRequest.disposeDownloadHandlerOnDispose = true;
+            ApplyRequestOptions(_args.Timeout, _args.WatchdogTime, _args.Headers);
+        }
+
+        /// <summary>
+        /// 请求成功时的回调
+        /// </summary>
+        protected override void OnRequestSucceed()
+        {
+            var fileData = _webRequest.downloadHandler.data;
+            if (fileData == null || fileData.Length == 0)
+            {
+                Status = EDownloadRequestStatus.Failed;
+                Error = $"[{GetType().Name}] URL: {URL} - Download bytes data is null or empty !";
+            }
+            else
+            {
+                Result = fileData;
+            }
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestBytesDownloader.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 6602c4be2ef295546b7bbb328de8fb0c
+guid: 38884a96e8c2df74082d4e059e2e73ed
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestDownloaderBase.cs

@@ -0,0 +1,290 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest 下载器基类
+    /// </summary>
+    /// <remarks>
+    /// 封装 UnityWebRequest 的通用下载逻辑，包括状态管理、进度追踪等。
+    /// 子类只需实现 CreateWebRequest 方法来创建特定类型的下载请求。
+    /// </remarks>
+    internal abstract class UnityWebRequestDownloaderBase : IDownloadRequest
+    {
+        private readonly UnityWebRequestDelegate _webRequestCreator;
+        protected UnityWebRequest _webRequest;
+
+        // 看门狗相关
+        private int _watchdogTime = 0;
+        private bool _watchdogAborted = false;
+        private long _lastDownloadBytes = -1;
+        private double _lastGetDataTime;
+
+        #region 接口实现
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        public string URL { get; }
+
+        /// <summary>
+        /// 是否完成
+        /// </summary>
+        /// <remarks>
+        /// 每次调用都会主动轮询请求 PollingRequest
+        /// </remarks>
+        public bool IsDone
+        {
+            get
+            {
+                PollingRequest();
+                return Status == EDownloadRequestStatus.Succeed
+                    || Status == EDownloadRequestStatus.Failed
+                    || Status == EDownloadRequestStatus.Aborted;
+            }
+        }
+
+        /// <summary>
+        /// 请求状态
+        /// </summary>
+        public EDownloadRequestStatus Status { get; protected set; }
+
+        /// <summary>
+        /// 当前下载进度（0f - 1f）
+        /// </summary>
+        public float DownloadProgress { get; private set; }
+
+        /// <summary>
+        /// 当前请求已接收的字节数
+        /// </summary>
+        public long DownloadedBytes { get; private set; }
+
+        /// <summary>
+        /// HTTP 返回码
+        /// </summary>
+        public long HttpCode { get; private set; }
+
+        /// <summary>
+        /// 错误信息
+        /// </summary>
+        public string Error { get; protected set; }
+        #endregion
+
+        /// <summary>
+        /// 构造下载器基类
+        /// </summary>
+        /// <param name="url">请求地址</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        protected UnityWebRequestDownloaderBase(string url, UnityWebRequestDelegate webRequestCreator)
+        {
+            URL = url;
+            _webRequestCreator = webRequestCreator;
+            Status = EDownloadRequestStatus.None;
+        }
+
+        /// <summary>
+        /// 发起请求
+        /// </summary>
+        public void SendRequest()
+        {
+            if (Status == EDownloadRequestStatus.None)
+            {
+                Status = EDownloadRequestStatus.Running;
+
+                try
+                {
+                    CreateWebRequest();
+
+                    if (_webRequest == null)
+                    {
+                        Status = EDownloadRequestStatus.Failed;
+                        Error = $"[{GetType().Name}] Created web request is null.";
+                    }
+                    else
+                    {
+                        _webRequest.SendWebRequest();
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Status = EDownloadRequestStatus.Failed;
+                    Error = $"[{GetType().Name}] Failed to create web request : {ex.Message}";
+                }
+            }
+        }
+
+        /// <summary>
+        /// 轮询请求
+        /// </summary>
+        public void PollingRequest()
+        {
+            if (Status != EDownloadRequestStatus.Running)
+                return;
+
+            DownloadProgress = _webRequest.downloadProgress;
+            DownloadedBytes = (long)_webRequest.downloadedBytes;
+
+            CheckWatchdog();
+            if (_webRequest.isDone == false)
+                return;
+
+            HttpCode = _webRequest.responseCode;
+#if UNITY_2020_3_OR_NEWER
+            bool isSuccess = _webRequest.result == UnityWebRequest.Result.Success;
+#else
+            bool isSuccess = !_webRequest.isNetworkError && !_webRequest.isHttpError;
+#endif
+
+            if (isSuccess)
+            {
+                Status = EDownloadRequestStatus.Succeed;
+                OnRequestSucceed();
+            }
+            else
+            {
+                Status = EDownloadRequestStatus.Failed;
+                Error = $"[{GetType().Name}] URL: {URL} - 错误: {_webRequest.error}";
+                OnRequestFailed();
+            }
+
+            // 完成后释放
+            DisposeWebRequest();
+        }
+
+        /// <summary>
+        /// 中止请求
+        /// </summary>
+        public void AbortRequest()
+        {
+            if (Status == EDownloadRequestStatus.None || Status == EDownloadRequestStatus.Running)
+            {
+                Status = EDownloadRequestStatus.Aborted;
+                if (_webRequest != null)
+                    _webRequest.Abort();
+            }
+        }
+
+        /// <summary>
+        /// 释放资源
+        /// </summary>
+        public void Dispose()
+        {
+            DisposeWebRequest();
+        }
+
+
+        /// <summary>
+        /// 创建 UnityWebRequest（子类实现）
+        /// </summary>
+        protected abstract void CreateWebRequest();
+
+        /// <summary>
+        /// 请求成功时的回调（子类可重写）
+        /// </summary>
+        protected virtual void OnRequestSucceed()
+        {
+        }
+
+        /// <summary>
+        /// 请求失败时的回调（子类可重写）
+        /// </summary>
+        protected virtual void OnRequestFailed()
+        {
+        }
+
+
+        /// <summary>
+        /// 创建 UnityWebRequest GET 请求
+        /// </summary>
+        /// <param name="requestUrl">请求地址</param>
+        /// <returns>UnityWebRequest 实例</returns>
+        protected UnityWebRequest CreateUnityWebRequestGet(string requestUrl)
+        {
+            if (_webRequestCreator != null)
+                return _webRequestCreator.Invoke(requestUrl);
+
+            return new UnityWebRequest(requestUrl, UnityWebRequest.kHttpVerbGET);
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest HEAD 请求
+        /// </summary>
+        /// <param name="requestUrl">请求地址</param>
+        /// <returns>UnityWebRequest 实例</returns>
+        protected UnityWebRequest CreateUnityWebRequestHead(string requestUrl)
+        {
+            return new UnityWebRequest(requestUrl, UnityWebRequest.kHttpVerbHEAD);
+        }
+
+        /// <summary>
+        /// 应用通用请求参数
+        /// </summary>
+        protected void ApplyRequestOptions(int timeout, int watchdogTime, Dictionary<string, string> headers)
+        {
+            if (_webRequest == null)
+                throw new YooInternalException("Web request is null !");
+
+            // 设置看门狗超时时间
+            _watchdogTime = watchdogTime;
+
+            // 设置响应的超时时间
+            if (timeout > 0)
+                _webRequest.timeout = timeout;
+
+            // 设置响应头
+            if (headers != null)
+            {
+                foreach (var header in headers)
+                {
+                    _webRequest.SetRequestHeader(header.Key, header.Value);
+                }
+            }
+        }
+
+        /// <summary>
+        /// 检测看门狗
+        /// </summary>
+        private void CheckWatchdog()
+        {
+            if (_watchdogTime == 0)
+                return;
+            if (_watchdogAborted)
+                return;
+
+#if UNITY_2020_3_OR_NEWER
+            double realtimeSinceStartup = UnityEngine.Time.realtimeSinceStartupAsDouble;
+#else
+            double realtimeSinceStartup = UnityEngine.Time.realtimeSinceStartup;
+#endif
+
+            if (DownloadedBytes != _lastDownloadBytes)
+            {
+                _lastDownloadBytes = DownloadedBytes;
+                _lastGetDataTime = realtimeSinceStartup;
+            }
+            else
+            {
+                double deltaTime = realtimeSinceStartup - _lastGetDataTime;
+                if (deltaTime > _watchdogTime)
+                {
+                    _watchdogAborted = true;
+                    AbortRequest(); //看门狗终止网络请求
+                }
+            }
+        }
+
+        /// <summary>
+        /// 释放资源
+        /// </summary>
+        private void DisposeWebRequest()
+        {
+            if (_webRequest != null)
+            {
+                //注意：引擎底层会自动调用Abort方法
+                _webRequest.Dispose();
+                _webRequest = null;
+            }
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestDownloaderBase.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 9e71e850eded0da43906cb4f7cb75629
+guid: 76b0712524ed69542914db8e44fa64fd
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestFileDownloader.cs

@@ -0,0 +1,56 @@
+using System;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest 文件下载器
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容保存到本地文件，支持断点续传和追加写入。
+    /// </remarks>
+    internal sealed class UnityWebRequestFileDownloader : UnityWebRequestDownloaderBase, IDownloadFileRequest
+    {
+        private readonly DownloadFileRequestArgs _args;
+
+        /// <summary>
+        /// 文件保存路径
+        /// </summary>
+        public string SavePath
+        {
+            get { return _args.SavePath; }
+        }
+
+        /// <summary>
+        /// 构造文件下载器
+        /// </summary>
+        /// <param name="args">文件下载参数</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        public UnityWebRequestFileDownloader(DownloadFileRequestArgs args, UnityWebRequestDelegate webRequestCreator)
+            : base(args.URL, webRequestCreator)
+        {
+            _args = args;
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest
+        /// </summary>
+        protected override void CreateWebRequest()
+        {
+            var handler = new DownloadHandlerFile(_args.SavePath, _args.AppendToFile);
+            handler.removeFileOnAbort = _args.RemoveFileOnAbort;
+
+            _webRequest = CreateUnityWebRequestGet(URL);
+            _webRequest.downloadHandler = handler;
+            _webRequest.disposeDownloadHandlerOnDispose = true;
+
+            // 断点续传：设置 Range 请求头
+            if (_args.ResumeFromBytes > 0)
+            {
+                _webRequest.SetRequestHeader("Range", $"bytes={_args.ResumeFromBytes}-");
+            }
+
+            ApplyRequestOptions(_args.Timeout, _args.WatchdogTime, _args.Headers);
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestFileDownloader.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 375d88bcf5b9a6146adaf98ceb5369f8
+guid: 101a4be1bb0a85c4d84ecbf3e74f89e4
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestHeadDownloader.cs

@@ -0,0 +1,124 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest HEAD 请求下载器
+    /// </summary>
+    /// <remarks>
+    /// 仅获取响应头信息，不下载实际内容。
+    /// 用于检查资源是否存在、获取资源大小、检查缓存有效性等场景。
+    /// </remarks>
+    internal sealed class UnityWebRequestHeadDownloader : UnityWebRequestDownloaderBase, IDownloadHeadRequest
+    {
+        // 注意：缓存响应头（因为 WebRequest 释放后无法获取）
+        private Dictionary<string, string> _cachedResponseHeaders;
+        private readonly DownloadDataRequestArgs _args;
+
+        /// <summary>
+        /// 获取 ETag 响应头
+        /// </summary>
+        public string ETag
+        {
+            get { return GetResponseHeader("ETag"); }
+        }
+
+        /// <summary>
+        /// 获取 Last-Modified 响应头
+        /// </summary>
+        public string LastModified
+        {
+            get { return GetResponseHeader("Last-Modified"); }
+        }
+
+        /// <summary>
+        /// 获取 Content-Type 响应头
+        /// </summary>
+        public string ContentType
+        {
+            get { return GetResponseHeader("Content-Type"); }
+        }
+
+        /// <summary>
+        /// 获取 Content-Length 响应头
+        /// 预期下载的总字节数
+        /// </summary>
+        public long ContentLength
+        {
+            get
+            {
+                string contentLengthStr = GetResponseHeader("Content-Length");
+                if (string.IsNullOrEmpty(contentLengthStr))
+                    return -1;
+
+                if (long.TryParse(contentLengthStr, out long contentLength))
+                {
+                    return contentLength;
+                }
+                else
+                {
+                    return -1;
+                }
+            }
+        }
+
+        /// <summary>
+        /// 构造 HEAD 请求下载器
+        /// </summary>
+        /// <param name="args">数据下载参数</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        public UnityWebRequestHeadDownloader(DownloadDataRequestArgs args, UnityWebRequestDelegate webRequestCreator)
+                            : base(args.URL, webRequestCreator)
+        {
+            _args = args;
+        }
+
+        /// <summary>
+        /// 获取响应头信息
+        /// </summary>
+        /// <param name="name">响应头名称（不区分大小写）</param>
+        /// <returns>响应头的值，如果不存在或请求未完成则返回 null</returns>
+        public string GetResponseHeader(string name)
+        {
+            if (_cachedResponseHeaders == null)
+                return null;
+
+            // 注意：UnityWebRequest 的响应头 key 是小写的
+            string lowerName = name.ToLowerInvariant();
+            if (_cachedResponseHeaders.TryGetValue(lowerName, out string value))
+                return value;
+
+            return null;
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest
+        /// </summary>
+        protected override void CreateWebRequest()
+        {
+            _webRequest = CreateUnityWebRequestHead(URL);
+            _webRequest.downloadHandler = null; // HEAD 请求不需要 DownloadHandler
+            ApplyRequestOptions(_args.Timeout, _args.WatchdogTime, _args.Headers);
+        }
+
+        /// <summary>
+        /// 请求成功时的回调
+        /// </summary>
+        protected override void OnRequestSucceed()
+        {
+            var headers = _webRequest.GetResponseHeaders();
+            if (headers != null)
+            {
+                _cachedResponseHeaders = new Dictionary<string, string>(headers.Count, StringComparer.OrdinalIgnoreCase);
+                foreach (var kvp in headers)
+                {
+                    string name = kvp.Key.ToLowerInvariant();
+                    string value = kvp.Value;
+                    _cachedResponseHeaders[name] = value;
+                }
+            }
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestHeadDownloader.cs.meta

@@ -0,0 +1,11 @@
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+guid: 8ed243d707130394aa85e20dee876d8e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestTextDownloader.cs

@@ -0,0 +1,61 @@
+using System;
+using UnityEngine.Networking;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// UnityWebRequest 文本下载器
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容解析为 UTF-8 文本字符串。
+    /// </remarks>
+    internal sealed class UnityWebRequestTextDownloader : UnityWebRequestDownloaderBase, IDownloadTextRequest
+    {
+        private readonly DownloadDataRequestArgs _args;
+
+        /// <summary>
+        /// 下载结果（文本字符串）
+        /// </summary>
+        public string Result { get; private set; }
+
+        /// <summary>
+        /// 构造文本下载器
+        /// </summary>
+        /// <param name="args">数据下载参数</param>
+        /// <param name="webRequestCreator">UnityWebRequest 创建器（可选）</param>
+        public UnityWebRequestTextDownloader(DownloadDataRequestArgs args, UnityWebRequestDelegate webRequestCreator)
+            : base(args.URL, webRequestCreator)
+        {
+            _args = args;
+        }
+
+        /// <summary>
+        /// 创建 UnityWebRequest
+        /// </summary>
+        protected override void CreateWebRequest()
+        {
+            var handler = new DownloadHandlerBuffer();
+            _webRequest = CreateUnityWebRequestGet(URL);
+            _webRequest.downloadHandler = handler;
+            _webRequest.disposeDownloadHandlerOnDispose = true;
+            ApplyRequestOptions(_args.Timeout, _args.WatchdogTime, _args.Headers);
+        }
+
+        /// <summary>
+        /// 请求成功时的回调
+        /// </summary>
+        protected override void OnRequestSucceed()
+        {
+            var fileText = _webRequest.downloadHandler.text;
+            if (string.IsNullOrEmpty(fileText))
+            {
+                Status = EDownloadRequestStatus.Failed;
+                Error = $"[{GetType().Name}] URL: {URL} - Download text data is null or empty";
+            }
+            else
+            {
+                Result = fileText;
+            }
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/UnityWebRequestTextDownloader.cs.meta

@@ -0,0 +1,11 @@
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+guid: 9b0bd3024ca5bae4dbdc05c7af7479df
+MonoImporter:
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+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/VirtualFileDownloader.cs

@@ -0,0 +1,149 @@
+using System;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// 模拟下载器
+    /// </summary>
+    /// <remarks>
+    /// 用于编辑器模式下模拟下载进度，不进行实际网络请求。
+    /// 根据配置的下载速度模拟进度变化。
+    /// </remarks>
+    internal sealed class VirtualFileDownloader : IDownloadFileRequest
+    {
+        private readonly DownloadSimulateRequestArgs _args;
+        private double _lastUpdateTime;
+
+        /// <summary>
+        /// 文件保存路径（模拟下载不需要）
+        /// </summary>
+        public string SavePath
+        {
+            get { return null; }
+        }
+
+        #region 接口实现
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        public string URL { get; }
+
+        /// <summary>
+        /// 是否完成
+        /// </summary>
+        public bool IsDone
+        {
+            get
+            {
+                PollingRequest();
+                return Status == EDownloadRequestStatus.Succeed
+                    || Status == EDownloadRequestStatus.Failed
+                    || Status == EDownloadRequestStatus.Aborted;
+            }
+        }
+
+        /// <summary>
+        /// 请求状态
+        /// </summary>
+        public EDownloadRequestStatus Status { get; private set; }
+
+        /// <summary>
+        /// 当前下载进度（0f - 1f）
+        /// </summary>
+        public float DownloadProgress { get; private set; }
+
+        /// <summary>
+        /// 当前请求已接收的字节数
+        /// </summary>
+        public long DownloadedBytes { get; private set; }
+
+        /// <summary>
+        /// HTTP 返回码（模拟固定返回 200）
+        /// </summary>
+        public long HttpCode { get; private set; }
+
+        /// <summary>
+        /// 错误信息
+        /// </summary>
+        public string Error { get; private set; }
+        #endregion
+
+        /// <summary>
+        /// 构造模拟下载器
+        /// </summary>
+        /// <param name="args">模拟下载参数</param>
+        public VirtualFileDownloader(DownloadSimulateRequestArgs args)
+        {
+            _args = args;
+            Status = EDownloadRequestStatus.None;
+        }
+
+        /// <summary>
+        /// 发起请求
+        /// </summary>
+        public void SendRequest()
+        {
+            if (Status == EDownloadRequestStatus.None)
+            {
+                Status = EDownloadRequestStatus.Running;
+                _lastUpdateTime = GetUnityEngineRealtime();
+            }
+        }
+
+        /// <summary>
+        /// 轮询请求
+        /// </summary>
+        public void PollingRequest()
+        {
+            if (Status != EDownloadRequestStatus.Running)
+                return;
+
+            double currentTime = GetUnityEngineRealtime();
+            double deltaTime = currentTime - _lastUpdateTime;
+            _lastUpdateTime = currentTime;
+
+            // 计算本帧下载的字节数
+            long downloadBytes = (long)(_args.DownloadSpeed * deltaTime);
+            DownloadedBytes += downloadBytes;
+
+            if (_args.FileSize > 0)
+                DownloadProgress = (float)DownloadedBytes / _args.FileSize;
+
+            // 检查是否完成
+            if (DownloadedBytes >= _args.FileSize)
+            {
+                HttpCode = 200;
+                DownloadProgress = 1f;
+                DownloadedBytes = _args.FileSize;
+                Status = EDownloadRequestStatus.Succeed;
+            }
+        }
+
+        /// <summary>
+        /// 中止请求
+        /// </summary>
+        public void AbortRequest()
+        {
+            if (Status == EDownloadRequestStatus.None || Status == EDownloadRequestStatus.Running)
+            {
+                Status = EDownloadRequestStatus.Aborted;
+            }
+        }
+
+        /// <summary>
+        /// 释放资源
+        /// </summary>
+        public void Dispose()
+        {
+        }
+
+        private double GetUnityEngineRealtime()
+        {
+#if UNITY_2020_3_OR_NEWER
+            return UnityEngine.Time.realtimeSinceStartupAsDouble;
+#else
+            return = UnityEngine.Time.realtimeSinceStartup;
+#endif
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DefaultDownloadRequest/VirtualFileDownloader.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 84daeb1559aadff40b5b5aa5c81d7d64
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DownloadDefine.cs

@@ -1,118 +0,0 @@
-
-namespace YooAsset
-{
-    /// <summary>
-    /// 下载器结束
-    /// </summary>
-    public struct DownloaderFinishData
-    {
-        /// <summary>
-        /// 所属包裹名称
-        /// </summary>
-        public string PackageName;
-
-        /// <summary>
-        /// 是否成功
-        /// </summary>
-        public bool Succeed;
-    }
-
-    /// <summary>
-    /// 下载器相关的更新数据
-    /// </summary>
-    public struct DownloadUpdateData
-    {
-        /// <summary>
-        /// 所属包裹名称
-        /// </summary>
-        public string PackageName;
-
-        /// <summary>
-        /// 下载进度 (0-1f)
-        /// </summary>
-        public float Progress;
-
-        /// <summary>
-        /// 下载文件总数
-        /// </summary>
-        public int TotalDownloadCount;
-
-        /// <summary>
-        /// 当前完成的下载文件数量
-        /// </summary>
-        public int CurrentDownloadCount;
-
-        /// <summary>
-        /// 下载数据总大小（单位：字节）
-        /// </summary>
-        public long TotalDownloadBytes;
-
-        /// <summary>
-        /// 当前完成的下载数据大小（单位：字节）
-        /// </summary>
-        public long CurrentDownloadBytes;
-    }
-
-    /// <summary>
-    /// 下载器相关的错误数据
-    /// </summary>
-    public struct DownloadErrorData
-    {
-        /// <summary>
-        /// 所属包裹名称
-        /// </summary>
-        public string PackageName;
-
-        /// <summary>
-        /// 下载失败的文件名称
-        /// </summary>
-        public string FileName;
-
-        /// <summary>
-        /// 错误信息
-        /// </summary>
-        public string ErrorInfo;
-    }
-
-    /// <summary>
-    /// 下载器相关的文件数据
-    /// </summary>
-    public struct DownloadFileData
-    {
-        /// <summary>
-        /// 所属包裹名称
-        /// </summary>
-        public string PackageName;
-
-        /// <summary>
-        /// 下载的文件名称
-        /// </summary>
-        public string FileName;
-
-        /// <summary>
-        /// 下载的文件大小
-        /// </summary>
-        public long FileSize;
-    }
-
-    /// <summary>
-    /// 导入文件的信息
-    /// </summary>
-    public struct ImportFileInfo
-    {
-        /// <summary>
-        /// 本地文件路径
-        /// </summary>
-        public string FilePath;
-
-        /// <summary>
-        /// 资源包名称
-        /// </summary>
-        public string BundleName;
-
-        /// <summary>
-        /// 资源包GUID
-        /// </summary>
-        public string BundleGUID;
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/DownloadSystemDefine.cs

@@ -0,0 +1,443 @@
+using System.Collections.Generic;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// 下载器结束
+    /// </summary>
+    public struct DownloaderFinishData
+    {
+        /// <summary>
+        /// 所属包裹名称
+        /// </summary>
+        public string PackageName;
+
+        /// <summary>
+        /// 是否成功
+        /// </summary>
+        public bool Succeed;
+    }
+
+    /// <summary>
+    /// 下载器相关的更新数据
+    /// </summary>
+    public struct DownloadUpdateData
+    {
+        /// <summary>
+        /// 所属包裹名称
+        /// </summary>
+        public string PackageName;
+
+        /// <summary>
+        /// 下载进度 (0-1f)
+        /// </summary>
+        public float Progress;
+
+        /// <summary>
+        /// 下载文件总数
+        /// </summary>
+        public int TotalDownloadCount;
+
+        /// <summary>
+        /// 当前完成的下载文件数量
+        /// </summary>
+        public int CurrentDownloadCount;
+
+        /// <summary>
+        /// 下载数据总大小（单位：字节）
+        /// </summary>
+        public long TotalDownloadBytes;
+
+        /// <summary>
+        /// 当前完成的下载数据大小（单位：字节）
+        /// </summary>
+        public long CurrentDownloadBytes;
+    }
+
+    /// <summary>
+    /// 下载器相关的错误数据
+    /// </summary>
+    public struct DownloadErrorData
+    {
+        /// <summary>
+        /// 所属包裹名称
+        /// </summary>
+        public string PackageName;
+
+        /// <summary>
+        /// 下载失败的文件名称
+        /// </summary>
+        public string FileName;
+
+        /// <summary>
+        /// 错误信息
+        /// </summary>
+        public string ErrorInfo;
+    }
+
+    /// <summary>
+    /// 下载器相关的文件数据
+    /// </summary>
+    public struct DownloadFileData
+    {
+        /// <summary>
+        /// 所属包裹名称
+        /// </summary>
+        public string PackageName;
+
+        /// <summary>
+        /// 下载的文件名称
+        /// </summary>
+        public string FileName;
+
+        /// <summary>
+        /// 下载的文件大小
+        /// </summary>
+        public long FileSize;
+    }
+
+    /// <summary>
+    /// 导入文件的信息
+    /// </summary>
+    public struct ImportFileInfo
+    {
+        /// <summary>
+        /// 本地文件路径
+        /// </summary>
+        public string FilePath;
+
+        /// <summary>
+        /// 资源包名称
+        /// </summary>
+        public string BundleName;
+
+        /// <summary>
+        /// 资源包GUID
+        /// </summary>
+        public string BundleGUID;
+    }
+
+
+    /// <summary>
+    /// 下载请求状态
+    /// </summary>
+    internal enum EDownloadRequestStatus
+    {
+        /// <summary>
+        /// 未开始
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// 进行中
+        /// </summary>
+        Running,
+
+        /// <summary>
+        /// 已成功
+        /// </summary>
+        Succeed,
+
+        /// <summary>
+        /// 已失败
+        /// </summary>
+        Failed,
+
+        /// <summary>
+        /// 已中止
+        /// </summary>
+        Aborted,
+    }
+
+    /// <summary>
+    /// 文件下载请求参数
+    /// </summary>
+    /// <remarks>
+    /// 用于将下载内容保存到本地文件的请求配置。
+    /// 支持断点续传和追加写入模式。
+    /// </remarks>
+    internal struct DownloadFileRequestArgs
+    {
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        public readonly string URL;
+
+        /// <summary>
+        /// 响应的超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 当 Timeout 设置为 0 时，不应用超时。
+        /// 设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
+        /// </remarks>
+        public readonly int Timeout;
+
+        /// <summary>
+        /// 看门狗超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 用于监控下载任务的数据接收情况。
+        /// 规则说明：
+        /// 1. 当设置值为 0 时，表示禁用看门狗监控。
+        /// 2. 每次接收到下载数据时，看门狗计时器会重置。
+        /// 3. 若在设定的时间范围内未收到任何数据，任务将被自动终止。
+        /// </remarks>
+        public readonly int WatchdogTime;
+
+        /// <summary>
+        /// 文件保存路径
+        /// </summary>
+        public readonly string SavePath;
+
+        /// <summary>
+        /// 是否追加写入文件
+        /// </summary>
+        /// <remarks>
+        /// 配合 ResumeFromBytes 使用，用于断点续传场景。
+        /// </remarks>
+        public readonly bool AppendToFile;
+
+        /// <summary>
+        /// 中止请求时是否删除目标文件
+        /// </summary>
+        public readonly bool RemoveFileOnAbort;
+
+        /// <summary>
+        /// 断点续传的起始字节（小于等于 0 表示不启用）
+        /// </summary>
+        /// <remarks>
+        /// 推荐由后端自动设置 Range 请求头："bytes={ResumeFromBytes}-"。
+        /// </remarks>
+        public readonly long ResumeFromBytes;
+
+        /// <summary>
+        /// 自定义请求头（可选）
+        /// </summary>
+        public Dictionary<string, string> Headers;
+
+        /// <summary>
+        /// 构造文件下载请求参数
+        /// </summary>
+        public DownloadFileRequestArgs(
+            string url,
+            string savePath,
+            int timeout,
+            int watchdogTime,
+            bool appendToFile = false,
+            bool removeFileOnAbort = true,
+            long resumeFromBytes = 0)
+        {
+            URL = url;
+            SavePath = savePath;
+            Timeout = timeout;
+            WatchdogTime = watchdogTime;
+            AppendToFile = appendToFile;
+            RemoveFileOnAbort = removeFileOnAbort;
+            ResumeFromBytes = resumeFromBytes;
+            Headers = null;
+        }
+
+        /// <summary>
+        /// 添加请求头数据
+        /// </summary>
+        public void AddRequestHeader(string name, string value)
+        {
+            if (Headers == null)
+                Headers = new Dictionary<string, string>(10);
+            Headers.Add(name, value);
+        }
+    }
+
+    /// <summary>
+    /// 数据下载请求参数（通用）
+    /// </summary>
+    /// <remarks>
+    /// 用于下载到内存的请求配置。
+    /// 可用于字节数组（bytes）或文本（text）下载。
+    /// </remarks>
+    internal struct DownloadDataRequestArgs
+    {
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        public readonly string URL;
+
+        /// <summary>
+        /// 响应的超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 当 Timeout 设置为 0 时，不应用超时。
+        /// 设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
+        /// </remarks>
+        public readonly int Timeout;
+
+        /// <summary>
+        /// 看门狗超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 用于监控下载任务的数据接收情况。
+        /// 规则说明：
+        /// 1. 当设置值为 0 时，表示禁用看门狗监控。
+        /// 2. 每次接收到下载数据时，看门狗计时器会重置。
+        /// 3. 若在设定的时间范围内未收到任何数据，任务将被自动终止。
+        /// </remarks>
+        public readonly int WatchdogTime;
+
+        /// <summary>
+        /// 自定义请求头（可选）
+        /// </summary>
+        public Dictionary<string, string> Headers;
+
+        /// <summary>
+        /// 构造数据下载请求参数
+        /// </summary>
+        /// <param name="url">请求地址</param>
+        /// <param name="options">通用请求参数</param>
+        public DownloadDataRequestArgs(string url, int timeout, int watchdogTime)
+        {
+            URL = url;
+            Timeout = timeout;
+            WatchdogTime = watchdogTime;
+            Headers = null;
+        }
+
+        /// <summary>
+        /// 添加请求头数据
+        /// </summary>
+        public void AddRequestHeader(string name, string value)
+        {
+            if (Headers == null)
+                Headers = new Dictionary<string, string>(10);
+            Headers.Add(name, value);
+        }
+    }
+
+    /// <summary>
+    /// AssetBundle 下载请求参数
+    /// </summary>
+    /// <remarks>
+    /// 用于下载并加载 Unity AssetBundle 的请求配置。
+    /// 支持 Unity 内置缓存机制和 CRC 校验。
+    /// </remarks>
+    internal struct DownloadAssetBundleRequestArgs
+    {
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        public readonly string URL;
+
+        /// <summary>
+        /// 响应的超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 当 Timeout 设置为 0 时，不应用超时。
+        /// 设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
+        /// </remarks>
+        public readonly int Timeout;
+
+        /// <summary>
+        /// 看门狗超时时间（单位：秒）
+        /// </summary>
+        /// <remarks>
+        /// 用于监控下载任务的数据接收情况。
+        /// 规则说明：
+        /// 1. 当设置值为 0 时，表示禁用看门狗监控。
+        /// 2. 每次接收到下载数据时，看门狗计时器会重置。
+        /// 3. 若在设定的时间范围内未收到任何数据，任务将被自动终止。
+        /// </remarks>
+        public readonly int WatchdogTime;
+
+        /// <summary>
+        /// 禁用 Unity 的网络缓存
+        /// </summary>
+        public readonly bool DisableUnityWebCache;
+
+        /// <summary>
+        /// AssetBundle 文件哈希（用于 UnityWebRequest 的缓存）
+        /// </summary>
+        /// <remarks>
+        /// 仅当 DisableUnityWebCache 为 false 时需要。
+        /// </remarks>
+        public readonly string FileHash;
+
+        /// <summary>
+        /// Unity CRC 校验值
+        /// </summary>
+        public readonly uint UnityCRC;
+
+        /// <summary>
+        /// 自定义请求头（可选）
+        /// </summary>
+        public Dictionary<string, string> Headers;
+
+        /// <summary>
+        /// 构造 AssetBundle 下载请求参数
+        /// </summary>
+        public DownloadAssetBundleRequestArgs(
+            string url,
+            int timeout,
+            int watchdogTime,
+            bool disableUnityWebCache = true,
+            string fileHash = null,
+            uint unityCrc = 0)
+        {
+            URL = url;
+            Timeout = timeout;
+            WatchdogTime = watchdogTime;
+            DisableUnityWebCache = disableUnityWebCache;
+            FileHash = fileHash;
+            UnityCRC = unityCrc;
+            Headers = null;
+        }
+
+        /// <summary>
+        /// 添加请求头数据
+        /// </summary>
+        public void AddRequestHeader(string name, string value)
+        {
+            if (Headers == null)
+                Headers = new Dictionary<string, string>(10);
+            Headers.Add(name, value);
+        }
+    }
+
+    /// <summary>
+    /// 模拟下载请求参数
+    /// </summary>
+    /// <remarks>
+    /// 用于编辑器模式下模拟下载进度，不进行实际网络请求。
+    /// </remarks>
+    internal struct DownloadSimulateRequestArgs
+    {
+        /// <summary>
+        /// 请求地址（仅用于标识）
+        /// </summary>
+        public readonly string URL;
+
+        /// <summary>
+        /// 模拟的文件大小（字节）
+        /// </summary>
+        public readonly long FileSize;
+
+        /// <summary>
+        /// 模拟的下载速度（字节/秒）
+        /// </summary>
+        /// <remarks>
+        /// 用于计算模拟的下载进度。
+        /// </remarks>
+        public readonly long DownloadSpeed;
+
+        /// <summary>
+        /// 构造模拟下载请求参数
+        /// </summary>
+        /// <param name="url">请求地址（仅用于标识）</param>
+        /// <param name="fileSize">模拟的文件大小（字节）</param>
+        /// <param name="downloadSpeed">模拟的下载速度（字节/秒），默认 1MB/s</param>
+        public DownloadSimulateRequestArgs(string url, long fileSize, long downloadSpeed = 1024 * 1024)
+        {
+            URL = url;
+            FileSize = fileSize;
+            DownloadSpeed = downloadSpeed > 0 ? downloadSpeed : 1024 * 1024;
+        }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/DownloadSystemDefine.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: eb0480e877454f7c944f66a01646b6d4
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/DownloadSystemHelper.cs

@@ -94,8 +94,12 @@ namespace YooAsset
         public static bool IsRequestLocalFile(string url)
         {
             //TODO UNITY_STANDALONE_OSX平台目前无法确定
+
+            // 本地文件传输协议
             if (url.StartsWith("file:"))
                 return true;
+
+            // JAR文件协议
             if (url.StartsWith("jar:file:"))
                 return true;
 

Assets/YooAsset/Runtime/DownloadSystem/Interface.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 4630dac2050606043bb146325fdce6ad
+guid: d724672f4d6f24b4db435d10eef6c40d
 folderAsset: yes
 DefaultImporter:
   externalObjects: {}

Assets/YooAsset/Runtime/DownloadSystem/Interface/IDownloadBackend.cs

@@ -0,0 +1,78 @@
+using System;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// 下载后台接口
+    /// </summary>
+    /// <remarks>
+    /// 不同网络库（UnityWebRequest / BestHTTP / 自研）实现该接口，用于创建具体下载请求。
+    /// 每个后台实例是独立的，不共享全局状态。
+    /// </remarks>
+    internal interface IDownloadBackend : IDisposable
+    {
+        /// <summary>
+        /// 后台名称（用于日志与调试）
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        /// 驱动更新
+        /// </summary>
+        /// <remarks>
+        /// 部分第三方网络库需要在 Unity 主线程中周期性调用 Update 进行驱动。
+        /// 不需要驱动的后台可实现为空方法。
+        /// </remarks>
+        void Update();
+
+        /// <summary>
+        /// 创建 HEAD 请求
+        /// </summary>
+        /// <remarks>
+        /// 仅获取响应头信息，不下载实际内容。
+        /// 用于检查资源是否存在、获取资源大小、检查缓存有效性等场景。
+        /// </remarks>
+        /// <param name="args">数据请求参数</param>
+        /// <returns>HEAD 请求实例</returns>
+        IDownloadHeadRequest CreateHeadRequest(DownloadDataRequestArgs args);
+
+        /// <summary>
+        /// 创建文件下载请求
+        /// </summary>
+        /// <param name="args">文件下载参数</param>
+        /// <returns>文件下载请求实例</returns>
+        IDownloadFileRequest CreateFileRequest(DownloadFileRequestArgs args);
+
+        /// <summary>
+        /// 创建内存下载请求（字节数组）
+        /// </summary>
+        /// <param name="args">数据下载参数</param>
+        /// <returns>字节下载请求实例</returns>
+        IDownloadBytesRequest CreateBytesRequest(DownloadDataRequestArgs args);
+
+        /// <summary>
+        /// 创建文本下载请求
+        /// </summary>
+        /// <param name="args">数据下载参数</param>
+        /// <returns>文本下载请求实例</returns>
+        IDownloadTextRequest CreateTextRequest(DownloadDataRequestArgs args);
+
+        /// <summary>
+        /// 创建 AssetBundle 下载请求
+        /// </summary>
+        /// <param name="args">AssetBundle 下载参数</param>
+        /// <returns>AssetBundle 下载请求实例</returns>
+        IDownloadAssetBundleRequest CreateAssetBundleRequest(DownloadAssetBundleRequestArgs args);
+
+        /// <summary>
+        /// 创建模拟下载请求
+        /// </summary>
+        /// <remarks>
+        /// 用于编辑器模式下模拟下载进度，不进行实际网络请求。
+        /// 可用于测试下载流程和 UI 展示。
+        /// </remarks>
+        /// <param name="args">模拟下载参数</param>
+        /// <returns>模拟下载请求实例</returns>
+        IDownloadFileRequest CreateSimulateRequest(DownloadSimulateRequestArgs args);
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/Interface/IDownloadBackend.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: e88c026ebbfb40258aad52ad1c2feb70
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/Interface/IDownloadRequest.cs

@@ -0,0 +1,194 @@
+using System;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// 可轮询的下载请求接口
+    /// </summary>
+    /// <remarks>
+    /// 上层通常会在每帧轮询 Status IsDone，并在完成后读取结果。
+    /// </remarks>
+    internal interface IDownloadRequest : IDisposable
+    {
+        /// <summary>
+        /// 请求地址
+        /// </summary>
+        string URL { get; }
+
+        /// <summary>
+        /// 是否完成（成功/失败/中止）
+        /// </summary>
+        bool IsDone { get; }
+
+        /// <summary>
+        /// 请求状态
+        /// </summary>
+        EDownloadRequestStatus Status { get; }
+
+        /// <summary>
+        /// 当前下载进度（0f - 1f）
+        /// </summary>
+        /// <remarks>
+        /// 部分情况下无法准确获取总长度，可返回 0。
+        /// </remarks>
+        float DownloadProgress { get; }
+
+        /// <summary>
+        /// 当前请求已接收的字节数
+        /// </summary>
+        /// <remarks>
+        /// 断点续传场景下，该值仅表示"本次请求新增下载的字节数"，不包含已存在的本地文件长度。
+        /// </remarks>
+        long DownloadedBytes { get; }
+
+        /// <summary>
+        /// HTTP 返回码
+        /// </summary>
+        /// <remarks>
+        /// 非 HTTP 协议可返回 0。使用 long 类型以兼容各种协议的返回码。
+        /// </remarks>
+        long HttpCode { get; }
+
+        /// <summary>
+        /// 错误信息
+        /// </summary>
+        /// <remarks>
+        /// 失败时不为空。
+        /// </remarks>
+        string Error { get; }
+
+        /// <summary>
+        /// 发起请求
+        /// </summary>
+        void SendRequest();
+
+        /// <summary>
+        /// 轮询请求
+        /// </summary>
+        void PollingRequest();
+
+        /// <summary>
+        /// 中止请求
+        /// </summary>
+        void AbortRequest();
+    }
+
+    /// <summary>
+    /// HEAD 请求接口（仅获取响应头）
+    /// </summary>
+    /// <remarks>
+    /// 用于检查资源是否存在、获取资源大小、检查缓存有效性等场景。
+    /// 不下载实际内容，仅获取响应头信息。
+    /// </remarks>
+    internal interface IDownloadHeadRequest : IDownloadRequest
+    {
+        /// <summary>
+        /// 获取 ETag 响应头
+        /// </summary>
+        /// <remarks>
+        /// 用于缓存验证，如果服务器未返回则为 null。
+        /// </remarks>
+        string ETag { get; }
+
+        /// <summary>
+        /// 获取 Last-Modified 响应头
+        /// </summary>
+        /// <remarks>
+        /// 资源最后修改时间，如果服务器未返回则为 null。
+        /// </remarks>
+        string LastModified { get; }
+
+        /// <summary>
+        /// 获取 Content-Type 响应头
+        /// </summary>
+        /// <remarks>
+        /// 资源的 MIME 类型，如果服务器未返回则为 null。
+        /// </remarks>
+        string ContentType { get; }
+
+        /// <summary>
+        /// 预期下载的总字节数（Content-Length）
+        /// </summary>
+        /// <remarks>
+        /// 从响应头 Content-Length 获取。
+        /// 如果服务器未返回或请求未完成，返回 -1。
+        /// 用于更准确的进度计算。
+        /// </remarks>
+        long ContentLength { get; }
+
+        /// <summary>
+        /// 获取响应头信息
+        /// </summary>
+        /// <param name="name">响应头名称（不区分大小写）</param>
+        /// <returns>响应头的值，如果不存在或请求未完成则返回 null</returns>
+        /// <remarks>
+        /// 常用响应头：Content-Length、Content-Type、ETag、Last-Modified 等。
+        /// </remarks>
+        string GetResponseHeader(string name);
+    }
+
+    /// <summary>
+    /// 文件下载请求接口
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容保存到指定的本地文件路径。
+    /// </remarks>
+    internal interface IDownloadFileRequest : IDownloadRequest
+    {
+        /// <summary>
+        /// 文件保存路径
+        /// </summary>
+        string SavePath { get; }
+    }
+
+    /// <summary>
+    /// 内存下载请求接口（字节数组）
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容保存到内存中的字节数组。
+    /// </remarks>
+    internal interface IDownloadBytesRequest : IDownloadRequest
+    {
+        /// <summary>
+        /// 下载结果（字节数组）
+        /// </summary>
+        /// <remarks>
+        /// 仅在请求成功时可用，失败时为 null。
+        /// </remarks>
+        byte[] Result { get; }
+    }
+
+    /// <summary>
+    /// 文本下载请求接口
+    /// </summary>
+    /// <remarks>
+    /// 将下载内容解析为 UTF-8 文本字符串。
+    /// </remarks>
+    internal interface IDownloadTextRequest : IDownloadRequest
+    {
+        /// <summary>
+        /// 下载结果（文本字符串）
+        /// </summary>
+        /// <remarks>
+        /// 仅在请求成功时可用，失败时为 null。
+        /// </remarks>
+        string Result { get; }
+    }
+
+    /// <summary>
+    /// AssetBundle 下载请求接口
+    /// </summary>
+    /// <remarks>
+    /// 下载并加载 Unity AssetBundle 资源包。
+    /// </remarks>
+    internal interface IDownloadAssetBundleRequest : IDownloadRequest
+    {
+        /// <summary>
+        /// 下载结果（AssetBundle 对象）
+        /// </summary>
+        /// <remarks>
+        /// 仅在请求成功时可用，失败时为 null。
+        /// </remarks>
+        UnityEngine.AssetBundle Result { get; }
+    }
+}

Assets/YooAsset/Runtime/DownloadSystem/Interface/IDownloadRequest.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 2a2aafeb309243f4959394a97d66b19f
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityAssetBundleRequestOperation.cs

@@ -1,113 +0,0 @@
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityAssetBundleRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            Done,
-        }
-
-        private UnityWebRequestAsyncOperation _requestOperation;
-        private DownloadHandlerAssetBundle _downloadhandler;
-        private readonly PackageBundle _packageBundle;
-        private readonly bool _disableUnityWebCache;
-        private ESteps _steps = ESteps.None;
-
-        /// <summary>
-        /// 请求结果
-        /// </summary>
-        public AssetBundle Result { private set; get; }
-
-        internal UnityAssetBundleRequestOperation(PackageBundle packageBundle, bool disableUnityWebCache, string url) : base(url)
-        {
-            _packageBundle = packageBundle;
-            _disableUnityWebCache = disableUnityWebCache;
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.CreateRequest)
-            {
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = _requestOperation.progress;
-                if (_requestOperation.isDone == false)
-                    return;
-
-                if (CheckRequestResult())
-                {
-                    AssetBundle assetBundle = _downloadhandler.assetBundle;
-                    if (assetBundle == null)
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"URL : {_requestURL} Download handler asset bundle object is null !";
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Result = assetBundle;
-                        Status = EOperationStatus.Succeed;
-                    }
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-        }
-
-        private void CreateWebRequest()
-        {
-            _downloadhandler = CreateWebDownloadHandler();
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.downloadHandler = _downloadhandler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _requestOperation = _webRequest.SendWebRequest();
-        }
-        private DownloadHandlerAssetBundle CreateWebDownloadHandler()
-        {
-            if (_disableUnityWebCache)
-            {
-                var downloadhandler = new DownloadHandlerAssetBundle(_requestURL, _packageBundle.UnityCRC);
-#if UNITY_2020_3_OR_NEWER
-                downloadhandler.autoLoadAssetBundle = false;
-#endif
-                return downloadhandler;
-            }
-            else
-            {
-                // 注意：优先从浏览器缓存里获取文件
-                // The file hash defining the version of the asset bundle.
-                Hash128 fileHash = Hash128.Parse(_packageBundle.FileHash);
-                var downloadhandler = new DownloadHandlerAssetBundle(_requestURL, fileHash, _packageBundle.UnityCRC);
-#if UNITY_2020_3_OR_NEWER
-                downloadhandler.autoLoadAssetBundle = false;
-#endif
-                return downloadhandler;
-            }
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityVirtualBundleRequestOperation.cs

@@ -1,65 +0,0 @@
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityVirtualBundleRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            Download,
-            Done,
-        }
-
-        private readonly PackageBundle _bundle;
-        private readonly int _downloadSpeed;
-        private ESteps _steps = ESteps.None;
-
-        internal UnityVirtualBundleRequestOperation(PackageBundle packageBundle, int downloadSpeed, string url) : base(url)
-        {
-            _bundle = packageBundle;
-            _downloadSpeed = downloadSpeed;
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.Download;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.Download)
-            {
-                // 模拟下载进度
-                float progress = 0;
-                if (DownloadedBytes > 0)
-                    progress = DownloadedBytes / _bundle.FileSize;
-                long downloadBytes = (long)((double)_downloadSpeed * Time.deltaTime);
-                
-                Progress = progress;
-                DownloadProgress = progress;
-                DownloadedBytes += downloadBytes;
-                if (DownloadedBytes < _bundle.FileSize)
-                    return;
-
-                Progress = 1f;
-                DownloadProgress = 1f;
-                DownloadedBytes = _bundle.FileSize;
-
-                _steps = ESteps.Done;
-                Status = EOperationStatus.Succeed;
-            }
-        }
-        internal override void InternalWaitForAsyncComplete()
-        {
-            if (_steps != ESteps.Done)
-            {
-                _steps = ESteps.Done;
-                Status = EOperationStatus.Failed;
-                Error = $"Try load bundle {_bundle.BundleName} from remote !";
-            }
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebCacheRequestOperation.cs

@@ -1,89 +0,0 @@
-using System.Collections;
-using System.Collections.Generic;
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityWebCacheRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            Done,
-        }
-
-        private UnityWebRequestAsyncOperation _requestOperation;
-        private readonly Dictionary<string, string> _headers = new Dictionary<string, string>();
-        private ESteps _steps = ESteps.None;
-
-
-        internal UnityWebCacheRequestOperation(string url) : base(url)
-        {
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.CreateRequest)
-            {
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = _requestOperation.progress;
-                if (_requestOperation.isDone == false)
-                    return;
-
-                if (CheckRequestResult())
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Succeed;
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-        }
-
-        /// <summary>
-        /// 设置请求头信息
-        /// </summary>
-        public void SetRequestHeader(string name, string value)
-        {
-            _headers.Add(name, value);
-        }
-
-        private void CreateWebRequest()
-        {
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-
-            // 设置消息头
-            foreach (var keyValuePair in _headers)
-            {
-                string name = keyValuePair.Key;
-                string value = keyValuePair.Value;
-                _webRequest.SetRequestHeader(name, value);
-            }
-
-            _requestOperation = _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebDataRequestOperation.cs

@@ -1,96 +0,0 @@
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityWebDataRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            Done,
-        }
-
-        private UnityWebRequestAsyncOperation _requestOperation;
-        private ESteps _steps = ESteps.None;
-
-        /// <summary>
-        /// 响应的超时时间（单位：秒），在经过Timeout的秒数后尝试中止。
-        /// 注意：当Timeout设置为0时，不会应用超时。
-        /// 注意：设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
-        /// </summary>
-        private readonly int _timeout;
-
-        /// <summary>
-        /// 请求结果
-        /// </summary>
-        public byte[] Result { private set; get; }
-
-
-        internal UnityWebDataRequestOperation(string url, int timeout) : base(url)
-        {
-            _timeout = timeout;
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.CreateRequest)
-            {
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = _requestOperation.progress;
-                if (_requestOperation.isDone == false)
-                    return;
-
-                if (CheckRequestResult())
-                {
-                    var fileData = _webRequest.downloadHandler.data;
-                    if (fileData == null || fileData.Length == 0)
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"URL : {_requestURL} Download handler data is null or empty !";
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Result = fileData;
-                        Status = EOperationStatus.Succeed;
-                    }
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-        }
-
-        private void CreateWebRequest()
-        {
-            DownloadHandlerBuffer handler = new DownloadHandlerBuffer();
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.timeout = _timeout;
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _requestOperation = _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebDataRequestOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: b7557eb146572de49a1ec9b3f3c0b706
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebFileRequestOperation.cs

@@ -1,83 +0,0 @@
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityWebFileRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            Done,
-        }
-
-        private UnityWebRequestAsyncOperation _requestOperation;
-        private readonly string _fileSavePath;
-        private ESteps _steps = ESteps.None;
-
-        /// <summary>
-        /// 响应的超时时间（单位：秒），在经过Timeout的秒数后尝试中止。
-        /// 注意：当Timeout设置为0时，不会应用超时。
-        /// 注意：设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
-        /// </summary>
-        private readonly int _timeout;
-
-
-        internal UnityWebFileRequestOperation(string url, string fileSavePath, int timeout) : base(url)
-        {
-            _fileSavePath = fileSavePath;
-            _timeout = timeout;
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.CreateRequest)
-            {
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = _requestOperation.progress;
-                if (_requestOperation.isDone == false)
-                    return;
-
-                if (CheckRequestResult())
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Succeed;
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-        }
-
-        private void CreateWebRequest()
-        {
-            DownloadHandlerFile handler = new DownloadHandlerFile(_fileSavePath);
-            handler.removeFileOnAbort = true;
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.timeout = _timeout;
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _requestOperation = _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebFileRequestOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 2ab5f2486d06e2642ba7aa9c9623430e
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebRequestOperation.cs

@@ -1,98 +0,0 @@
-using System;
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal abstract class UnityWebRequestOperation : AsyncOperationBase
-    {
-        protected UnityWebRequest _webRequest;
-        protected readonly string _requestURL;
-        private bool _isAbort = false;
-
-        /// <summary>
-        /// HTTP返回码
-        /// </summary>
-        public long HttpCode { private set; get; }
-
-        /// <summary>
-        /// 当前下载的字节数
-        /// </summary>
-        public long DownloadedBytes { protected set; get; }
-
-        /// <summary>
-        /// 当前下载进度（0f - 1f）
-        /// </summary>
-        public float DownloadProgress { protected set; get; }
-
-        /// <summary>
-        /// 请求的URL地址
-        /// </summary>
-        public string URL
-        {
-            get { return _requestURL; }
-        }
-
-        internal UnityWebRequestOperation(string url)
-        {
-            _requestURL = url;
-        }
-        internal override void InternalAbort()
-        {
-            //TODO
-            // 1. 编辑器下停止运行游戏的时候主动终止下载任务
-            // 2. 真机上销毁包裹的时候主动终止下载任务
-            if (_isAbort == false)
-            {
-                if (_webRequest != null)
-                {
-                    _webRequest.Abort();
-                    _isAbort = true;
-                }
-            }
-        }
-
-        /// <summary>
-        /// 释放下载器
-        /// </summary>
-        protected void DisposeRequest()
-        {
-            if (_webRequest != null)
-            {
-                //注意：引擎底层会自动调用Abort方法
-                _webRequest.Dispose();
-                _webRequest = null;
-            }
-        }
-
-        /// <summary>
-        /// 检测请求结果
-        /// </summary>
-        protected bool CheckRequestResult()
-        {
-            HttpCode = _webRequest.responseCode;
-
-#if UNITY_2020_3_OR_NEWER
-            if (_webRequest.result != UnityWebRequest.Result.Success)
-            {
-                Error = $"URL : {_requestURL} Error : {_webRequest.error}";
-                return false;
-            }
-            else
-            {
-                return true;
-            }
-#else
-            if (_webRequest.isNetworkError || _webRequest.isHttpError)
-            {
-                Error = $"URL : {_requestURL} Error : {_webRequest.error}";
-                return false;
-            }
-            else
-            {
-                return true;
-            }
-#endif
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebRequestOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 4e5c3c1a1655a8b41b585c6811201583
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebTextRequestOperation.cs

@@ -1,96 +0,0 @@
-using UnityEngine.Networking;
-using UnityEngine;
-
-namespace YooAsset
-{
-    internal class UnityWebTextRequestOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            Done,
-        }
-
-        private UnityWebRequestAsyncOperation _requestOperation;
-        private ESteps _steps = ESteps.None;
-
-        /// <summary>
-        /// 响应的超时时间（单位：秒），在经过Timeout的秒数后尝试中止。
-        /// 注意：当Timeout设置为0时，不会应用超时。
-        /// 注意：设置的超时值可能应用于Android上的每个URL重定向，这可能会导致响应时间增加。
-        /// </summary>
-        private readonly int _timeout;
-
-        /// <summary>
-        /// 请求结果
-        /// </summary>
-        public string Result { private set; get; }
-
-
-        internal UnityWebTextRequestOperation(string url, int timeout) : base(url)
-        {
-            _timeout = timeout;
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            if (_steps == ESteps.CreateRequest)
-            {
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = _requestOperation.progress;
-                if (_requestOperation.isDone == false)
-                    return;
-
-                if (CheckRequestResult())
-                {
-                    var fileText = _webRequest.downloadHandler.text;
-                    if (string.IsNullOrEmpty(fileText))
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"URL : {_requestURL} Download handler text is null or empty !";
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Result = fileText;
-                        Status = EOperationStatus.Succeed;
-                    }
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-        }
-
-        private void CreateWebRequest()
-        {
-            DownloadHandlerBuffer handler = new DownloadHandlerBuffer();
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.timeout = _timeout;
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _requestOperation = _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/DownloadSystem/Operation/Internal/UnityWebTextRequestOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: a488de5dcd6f4c448a47c4b574d5c9bc
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/CatalogTools.cs

@@ -118,6 +118,34 @@ namespace YooAsset
             Debug.Log($"Succeed to save catalog file : {binaryFilePath}");
             return true;
         }
+
+        /// <summary>
+        /// 生成空的包裹内置资源目录文件
+        /// </summary>
+        public static bool CreateEmptyCatalogFile(string packageName, string packageVersion, string outputPath)
+        {
+            // 创建内置清单实例
+            var buildinFileCatalog = new DefaultBuildinFileCatalog();
+            buildinFileCatalog.FileVersion = CatalogDefine.FileVersion;
+            buildinFileCatalog.PackageName = packageName;
+            buildinFileCatalog.PackageVersion = packageVersion;
+
+            // 创建输出文件
+            string jsonFilePath = $"{outputPath}/{DefaultBuildinFileSystemDefine.BuildinCatalogJsonFileName}";
+            if (File.Exists(jsonFilePath))
+                File.Delete(jsonFilePath);
+            SerializeToJson(jsonFilePath, buildinFileCatalog);
+
+            // 创建输出文件
+            string binaryFilePath = $"{outputPath}/{DefaultBuildinFileSystemDefine.BuildinCatalogBinaryFileName}";
+            if (File.Exists(binaryFilePath))
+                File.Delete(binaryFilePath);
+            SerializeToBinary(binaryFilePath, buildinFileCatalog);
+
+            UnityEditor.AssetDatabase.Refresh();
+            Debug.Log($"Succeed to save catalog file : {binaryFilePath}");
+            return true;
+        }
 #endif
 
         /// <summary>

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/DefaultBuildinFileSystem.cs

@@ -25,6 +25,11 @@ namespace YooAsset
         protected IFileSystem _unpackFileSystem;
         protected string _packageRoot;
 
+        /// <summary>
+        /// 下载后台接口
+        /// </summary>
+        public IDownloadBackend DownloadBackend { private set; get; }
+
         /// <summary>
         /// 包裹名称
         /// </summary>
@@ -66,7 +71,7 @@ namespace YooAsset
         /// <summary>
         /// 自定义参数：初始化的时候缓存文件校验最大并发数
         /// </summary>
-        public int FileVerifyMaxConcurrency { private set; get; } = int.MaxValue;
+        public int FileVerifyMaxConcurrency { private set; get; } = 32;
 
         /// <summary>
         /// 自定义参数：数据文件追加文件格式
@@ -89,6 +94,11 @@ namespace YooAsset
         /// </summary>
         public string CopyBuildinPackageManifestDestRoot { private set; get; }
 
+        /// <summary>
+        /// 自定义参数：解压文件系统的根目录
+        /// </summary>
+        public string UnpackFileSystemRoot { private set; get; }
+
         /// <summary>
         ///  自定义参数：解密服务接口的实例类
         /// </summary>
@@ -151,6 +161,13 @@ namespace YooAsset
                 var operation = new DBFSLoadRawBundleOperation(this, bundle);
                 return operation;
             }
+#if TUANJIE_1_7_OR_NEWER
+            else if (bundle.BundleType == (int)EBuildBundleType.InstantBundle)
+            {
+                var operation = new DBFSLoadInstantBundleOperation(this, bundle);
+                return operation;
+            }
+#endif
             else
             {
                 string error = $"{nameof(DefaultBuildinFileSystem)} not support load bundle type : {bundle.BundleType}";
@@ -190,6 +207,10 @@ namespace YooAsset
             {
                 CopyBuildinPackageManifestDestRoot = (string)value;
             }
+            else if (name == FileSystemParametersDefine.UNPACK_FILE_SYSTEM_ROOT)
+            {
+                UnpackFileSystemRoot = (string)value;
+            }
             else if (name == FileSystemParametersDefine.DECRYPTION_SERVICES)
             {
                 DecryptionServices = (IDecryptionServices)value;
@@ -216,6 +237,10 @@ namespace YooAsset
             else
                 _packageRoot = packageRoot;
 
+            // 创建默认的下载后台接口
+            if (DownloadBackend == null)
+                DownloadBackend = new UnityWebRequestBackend(DownloadSystemHelper.UnityWebRequestCreater);
+
             // 创建解压文件系统
             var remoteServices = new DefaultUnpackRemoteServices(_packageRoot);
             _unpackFileSystem = new DefaultUnpackFileSystem();
@@ -226,7 +251,7 @@ namespace YooAsset
             _unpackFileSystem.SetParameter(FileSystemParametersDefine.APPEND_FILE_EXTENSION, AppendFileExtension);
             _unpackFileSystem.SetParameter(FileSystemParametersDefine.DECRYPTION_SERVICES, DecryptionServices);
             _unpackFileSystem.SetParameter(FileSystemParametersDefine.COPY_LOCAL_FILE_SERVICES, CopyLocalFileServices);
-            _unpackFileSystem.OnCreate(packageName, null);
+            _unpackFileSystem.OnCreate(packageName, UnpackFileSystemRoot);
         }
         public virtual void OnDestroy()
         {

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/DBFSInitializeOperation.cs

@@ -78,7 +78,7 @@ namespace YooAsset
                     string packageVersion = _requestBuildinPackageVersionOp.PackageVersion;
                     string destFilePath = GetCopyPackageHashDestPath(packageVersion);
                     string sourceFilePath = _fileSystem.GetBuildinPackageHashFilePath(packageVersion);
-                    _copyBuildinHashFileOp = new CopyBuildinFileOperation(sourceFilePath, destFilePath);
+                    _copyBuildinHashFileOp = new CopyBuildinFileOperation(_fileSystem, sourceFilePath, destFilePath);
                     _copyBuildinHashFileOp.StartOperation();
                     AddChildOperation(_copyBuildinHashFileOp);
                 }
@@ -106,7 +106,7 @@ namespace YooAsset
                     string packageVersion = _requestBuildinPackageVersionOp.PackageVersion;
                     string destFilePath = GetCopyPackageManifestDestPath(packageVersion);
                     string sourceFilePath = _fileSystem.GetBuildinPackageManifestFilePath(packageVersion);
-                    _copyBuildinManifestFileOp = new CopyBuildinFileOperation(sourceFilePath, destFilePath);
+                    _copyBuildinManifestFileOp = new CopyBuildinFileOperation(_fileSystem, sourceFilePath, destFilePath);
                     _copyBuildinManifestFileOp.StartOperation();
                     AddChildOperation(_copyBuildinManifestFileOp);
                 }

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/internal/CopyBuildinFileOperation.cs

@@ -14,13 +14,15 @@ namespace YooAsset
             Done,
         }
 
-        private UnityWebFileRequestOperation _webFileRequestOp;
+        private readonly DefaultBuildinFileSystem _fileSystem;
         private readonly string _sourceFilePath;
         private readonly string _destFilePath;
+        private IDownloadFileRequest _webFileRequestOp;
         private ESteps _steps = ESteps.None;
 
-        public CopyBuildinFileOperation(string sourceFilePath, string destFilePath)
+        public CopyBuildinFileOperation(DefaultBuildinFileSystem fileSystem, string sourceFilePath, string destFilePath)
         {
+            _fileSystem = fileSystem;
             _sourceFilePath = sourceFilePath;
             _destFilePath = destFilePath;
         }
@@ -76,16 +78,15 @@ namespace YooAsset
                 if (_webFileRequestOp == null)
                 {
                     string url = DownloadSystemHelper.ConvertToWWWPath(_sourceFilePath);
-                    _webFileRequestOp = new UnityWebFileRequestOperation(url, _destFilePath, 60);
-                    _webFileRequestOp.StartOperation();
-                    AddChildOperation(_webFileRequestOp);
+                    var args = new DownloadFileRequestArgs(url, _destFilePath, 60, 0);
+                    _webFileRequestOp = _fileSystem.DownloadBackend.CreateFileRequest(args);
+                    _webFileRequestOp.SendRequest();
                 }
 
-                _webFileRequestOp.UpdateOperation();
                 if (_webFileRequestOp.IsDone == false)
                     return;
 
-                if (_webFileRequestOp.Status == EOperationStatus.Succeed)
+                if (_webFileRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/internal/LoadBuildinCatalogFileOperation.cs

@@ -15,7 +15,7 @@ namespace YooAsset
         }
 
         private readonly DefaultBuildinFileSystem _fileSystem;
-        private UnityWebDataRequestOperation _webDataRequestOp;
+        private IDownloadBytesRequest _webDataRequestOp;
         private byte[] _fileData;
         private ESteps _steps = ESteps.None;
 
@@ -57,16 +57,15 @@ namespace YooAsset
                 {
                     string filePath = _fileSystem.GetCatalogBinaryFileLoadPath();
                     string url = DownloadSystemHelper.ConvertToWWWPath(filePath);
-                    _webDataRequestOp = new UnityWebDataRequestOperation(url, 60);
-                    _webDataRequestOp.StartOperation();
-                    AddChildOperation(_webDataRequestOp);
+                    var args = new DownloadDataRequestArgs(url, 60, 0);
+                    _webDataRequestOp = _fileSystem.DownloadBackend.CreateBytesRequest(args);
+                    _webDataRequestOp.SendRequest();
                 }
 
-                _webDataRequestOp.UpdateOperation();
                 if (_webDataRequestOp.IsDone == false)
                     return;
 
-                if (_webDataRequestOp.Status == EOperationStatus.Succeed)
+                if (_webDataRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _fileData = _webDataRequestOp.Result;
                     _steps = ESteps.LoadCatalog;
@@ -87,11 +86,11 @@ namespace YooAsset
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;
                 }
-                catch (Exception e)
+                catch (Exception ex)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Failed;
-                    Error = $"Failed to load catalog file : {e.Message}";
+                    Error = $"Failed to load catalog file : {ex.Message}";
                 }
             }
         }

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/internal/LoadBuildinPackageManifestOperation.cs

@@ -17,7 +17,7 @@ namespace YooAsset
         private readonly DefaultBuildinFileSystem _fileSystem;
         private readonly string _packageVersion;
         private readonly string _packageHash;
-        private UnityWebDataRequestOperation _webDataRequestOp;
+        private IDownloadBytesRequest _webDataRequestOp;
         private DeserializeManifestOperation _deserializer;
         private byte[] _fileData;
         private ESteps _steps = ESteps.None;
@@ -63,16 +63,15 @@ namespace YooAsset
                 {
                     string filePath = _fileSystem.GetBuildinPackageManifestFilePath(_packageVersion);
                     string url = DownloadSystemHelper.ConvertToWWWPath(filePath);
-                    _webDataRequestOp = new UnityWebDataRequestOperation(url, 60);
-                    _webDataRequestOp.StartOperation();
-                    AddChildOperation(_webDataRequestOp);
+                    var args = new DownloadDataRequestArgs(url, 60, 0);
+                    _webDataRequestOp = _fileSystem.DownloadBackend.CreateBytesRequest(args);
+                    _webDataRequestOp.SendRequest();
                 }
 
-                _webDataRequestOp.UpdateOperation();
                 if (_webDataRequestOp.IsDone == false)
                     return;
 
-                if (_webDataRequestOp.Status == EOperationStatus.Succeed)
+                if (_webDataRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _fileData = _webDataRequestOp.Result;
                     _steps = ESteps.VerifyFileData;

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/internal/RequestBuildinPackageHashOperation.cs

@@ -15,7 +15,7 @@ namespace YooAsset
 
         private readonly DefaultBuildinFileSystem _fileSystem;
         private readonly string _packageVersion;
-        private UnityWebTextRequestOperation _webTextRequestOp;
+        private IDownloadTextRequest _webTextRequestOp;
         private ESteps _steps = ESteps.None;
 
         /// <summary>
@@ -58,16 +58,15 @@ namespace YooAsset
                 {
                     string filePath = _fileSystem.GetBuildinPackageHashFilePath(_packageVersion);
                     string url = DownloadSystemHelper.ConvertToWWWPath(filePath);
-                    _webTextRequestOp = new UnityWebTextRequestOperation(url, 60);
-                    _webTextRequestOp.StartOperation();
-                    AddChildOperation(_webTextRequestOp);
+                    var args = new DownloadDataRequestArgs(url, 60, 0);
+                    _webTextRequestOp = _fileSystem.DownloadBackend.CreateTextRequest(args);
+                    _webTextRequestOp.SendRequest();
                 }
 
-                _webTextRequestOp.UpdateOperation();
                 if (_webTextRequestOp.IsDone == false)
                     return;
 
-                if (_webTextRequestOp.Status == EOperationStatus.Succeed)
+                if (_webTextRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     PackageHash = _webTextRequestOp.Result;
                     _steps = ESteps.CheckResult;

Assets/YooAsset/Runtime/FileSystem/DefaultBuildinFileSystem/Operation/internal/RequestBuildinPackageVersionOperation.cs

@@ -14,7 +14,7 @@ namespace YooAsset
         }
 
         private readonly DefaultBuildinFileSystem _fileSystem;
-        private UnityWebTextRequestOperation _webTextRequestOp;
+        private IDownloadTextRequest _webTextRequestOp;
         private ESteps _steps = ESteps.None;
 
         /// <summary>
@@ -56,16 +56,15 @@ namespace YooAsset
                 {
                     string filePath = _fileSystem.GetBuildinPackageVersionFilePath();
                     string url = DownloadSystemHelper.ConvertToWWWPath(filePath);
-                    _webTextRequestOp = new UnityWebTextRequestOperation(url, 60);
-                    _webTextRequestOp.StartOperation();
-                    AddChildOperation(_webTextRequestOp);
+                    var args = new DownloadDataRequestArgs(url, 60, 0);
+                    _webTextRequestOp = _fileSystem.DownloadBackend.CreateTextRequest(args);
+                    _webTextRequestOp.SendRequest();
                 }
 
-                _webTextRequestOp.UpdateOperation();
                 if (_webTextRequestOp.IsDone == false)
                     return;
 
-                if (_webTextRequestOp.Status == EOperationStatus.Succeed)
+                if (_webTextRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     PackageVersion = _webTextRequestOp.Result;
                     _steps = ESteps.CheckResult;

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/DefaultCacheFileSystem.cs

@@ -23,10 +23,14 @@ namespace YooAsset
         protected string _cacheManifestFilesRoot;
 
         /// <summary>
-        /// 下载中心
-        /// 说明：当异步操作任务终止的时候，所有下载子任务都会一同被终止！
+        /// 下载调度器
         /// </summary>
-        public DownloadCenterOperation DownloadCenter { set; get; }
+        public DownloadSchedulerOperation DownloadScheduler { set; get; }
+
+        /// <summary>
+        /// 下载后台接口
+        /// </summary>
+        public IDownloadBackend DownloadBackend { private set; get; }
 
         /// <summary>
         /// 包裹名称
@@ -73,8 +77,10 @@ namespace YooAsset
 
         /// <summary>
         /// 自定义参数：初始化的时候缓存文件校验最大并发数
+        /// 默认值：32（推荐范围 1-128）
+        /// 说明：过大的值可能导致线程池任务过多，影响系统稳定性 
         /// </summary>
-        public int FileVerifyMaxConcurrency { private set; get; } = int.MaxValue;
+        public int FileVerifyMaxConcurrency { private set; get; } = 32;
 
         /// <summary>
         /// 自定义参数：数据文件追加文件格式
@@ -88,18 +94,22 @@ namespace YooAsset
 
         /// <summary>
         /// 自定义参数：最大并发连接数
+        /// 默认值：10（推荐范围 1-32）
+        /// 说明：过大的并发数可能被服务器限流，也会增加本地资源消耗 
         /// </summary>
-        public int DownloadMaxConcurrency { private set; get; } = int.MaxValue;
+        public int DownloadMaxConcurrency { private set; get; } = 10;
 
         /// <summary>
         /// 自定义参数：每帧发起的最大请求数
+        /// 默认值：5（推荐范围 1-10） 
+        /// 说明：避免单帧发起过多请求导致卡顿 
         /// </summary>
-        public int DownloadMaxRequestPerFrame { private set; get; } = int.MaxValue;
+        public int DownloadMaxRequestPerFrame { private set; get; } = 5;
 
         /// <summary>
         /// 自定义参数：下载任务的看门狗机制监控时间
         /// </summary>
-        public int DownloadWatchDogTime { private set; get; } = int.MaxValue;
+        public int DownloadWatchDogTime { private set; get; } = 0;
 
         /// <summary>
         /// 自定义参数：启用断点续传的最小尺寸
@@ -158,6 +168,11 @@ namespace YooAsset
                 var operation = new ClearUnusedCacheBundleFilesOperation(this, manifest);
                 return operation;
             }
+            else if (options.ClearMode == EFileClearMode.ClearBundleFilesByLocations.ToString())
+            {
+                var operation = new ClearCacheBundleFilesByLocationsOperaiton(this, manifest, options.ClearParam);
+                return operation;
+            }
             else if (options.ClearMode == EFileClearMode.ClearBundleFilesByTags.ToString())
             {
                 var operation = new ClearCacheBundleFilesByTagsOperaiton(this, manifest, options.ClearParam);
@@ -237,7 +252,14 @@ namespace YooAsset
             else if (name == FileSystemParametersDefine.FILE_VERIFY_MAX_CONCURRENCY)
             {
                 int convertValue = Convert.ToInt32(value);
-                FileVerifyMaxConcurrency = Mathf.Clamp(convertValue, 1, int.MaxValue);
+                if (convertValue > 256)
+                {
+                    YooLogger.Warning($"FILE_VERIFY_MAX_CONCURRENCY value {convertValue} is too large, clamped to 256. Recommended range: 1 - 128.");
+                }
+
+                // 限制在合理范围内：1-256                                                                             
+                // 超过 256 的并发数对于文件验证来说没有意义，反而会增加线程池压力  
+                FileVerifyMaxConcurrency = Mathf.Clamp(convertValue, 1, 256);
             }
             else if (name == FileSystemParametersDefine.APPEND_FILE_EXTENSION)
             {
@@ -250,17 +272,27 @@ namespace YooAsset
             else if (name == FileSystemParametersDefine.DOWNLOAD_MAX_CONCURRENCY)
             {
                 int convertValue = Convert.ToInt32(value);
-                DownloadMaxConcurrency = Mathf.Clamp(convertValue, 1, int.MaxValue);
+                if (convertValue > 64)
+                {
+                    YooLogger.Warning($"DOWNLOAD_MAX_CONCURRENCY value {convertValue} is too large, clamped to 64. Recommended range: 1 - 32.");
+                }
+
+                DownloadMaxConcurrency = Mathf.Clamp(convertValue, 1, 64);
             }
             else if (name == FileSystemParametersDefine.DOWNLOAD_MAX_REQUEST_PER_FRAME)
             {
                 int convertValue = Convert.ToInt32(value);
-                DownloadMaxRequestPerFrame = Mathf.Clamp(convertValue, 1, int.MaxValue);
+                if (convertValue > 20)
+                {
+                    YooLogger.Warning($"DOWNLOAD_MAX_REQUEST_PER_FRAME value {convertValue} is too large, clamped to 20. Recommended range: 1 - 10.");
+                }
+
+                DownloadMaxRequestPerFrame = Mathf.Clamp(convertValue, 1, 20);
             }
             else if (name == FileSystemParametersDefine.DOWNLOAD_WATCH_DOG_TIME)
             {
                 int convertValue = Convert.ToInt32(value);
-                DownloadWatchDogTime = Mathf.Clamp(convertValue, 1, int.MaxValue);
+                DownloadWatchDogTime = Mathf.Clamp(convertValue, 0, int.MaxValue);
             }
             else if (name == FileSystemParametersDefine.RESUME_DOWNLOAD_MINMUM_SIZE)
             {
@@ -299,13 +331,17 @@ namespace YooAsset
             _cacheBundleFilesRoot = PathUtility.Combine(_packageRoot, DefaultCacheFileSystemDefine.BundleFilesFolderName);
             _cacheManifestFilesRoot = PathUtility.Combine(_packageRoot, DefaultCacheFileSystemDefine.ManifestFilesFolderName);
             _tempFilesRoot = PathUtility.Combine(_packageRoot, DefaultCacheFileSystemDefine.TempFilesFolderName);
+
+            // 创建默认的下载后台接口
+            if (DownloadBackend == null)
+                DownloadBackend = new UnityWebRequestBackend(DownloadSystemHelper.UnityWebRequestCreater);
         }
         public virtual void OnDestroy()
         {
-            if (DownloadCenter != null)
+            if (DownloadScheduler != null)
             {
-                DownloadCenter.AbortOperation();
-                DownloadCenter = null;
+                DownloadScheduler.Dispose();
+                DownloadScheduler = null;
             }
         }
 
@@ -471,7 +507,7 @@ namespace YooAsset
         {
             if (_records.ContainsKey(bundle.BundleGUID))
             {
-                throw new Exception("Should never get here !");
+                throw new YooInternalException();
             }
 
             string infoFilePath = GetBundleInfoFilePath(bundle);
@@ -493,9 +529,9 @@ namespace YooAsset
                 // 写入文件信息
                 WriteBundleInfoFile(infoFilePath, bundle.FileCRC, bundle.FileSize);
             }
-            catch (Exception e)
+            catch (Exception ex)
             {
-                YooLogger.Error($"Failed to write cache file ! {e.Message}");
+                YooLogger.Error($"Failed to write cache file ! {ex.Message}");
                 return false;
             }
 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Elements/RecordFileElement.cs

@@ -37,9 +37,9 @@ namespace YooAsset
                     return false;
                 }
             }
-            catch (Exception e)
+            catch (Exception ex)
             {
-                YooLogger.Error($"Failed to delete cache file ! {e.Message}");
+                YooLogger.Error($"Failed to delete cache file ! {ex.Message}");
                 return false;
             }
         }

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Elements/VerifyFileElement.cs

@@ -33,9 +33,9 @@ namespace YooAsset
             {
                 Directory.Delete(FileRootPath, true);
             }
-            catch (System.Exception e)
+            catch (System.Exception ex)
             {
-                YooLogger.Warning($"Failed to delete cache bundle folder : {e}");
+                YooLogger.Warning($"Failed to delete cache bundle folder : {ex}");
             }
         }
     }

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/DCFSInitializeOperation.cs

@@ -9,7 +9,7 @@ namespace YooAsset
             CheckAppFootPrint,
             SearchCacheFiles,
             VerifyCacheFiles,
-            CreateDownloadCenter,
+            CreateDownloadScheduler,
             Done,
         }
 
@@ -110,7 +110,7 @@ namespace YooAsset
 
                 if (_verifyCacheFilesOp.Status == EOperationStatus.Succeed)
                 {
-                    _steps = ESteps.CreateDownloadCenter;
+                    _steps = ESteps.CreateDownloadScheduler;
                     YooLogger.Log($"Package '{_fileSystem.PackageName}' '{_fileSystem.GetType().Name}' cached files count : {_fileSystem.FileCount}");
                 }
                 else
@@ -121,13 +121,13 @@ namespace YooAsset
                 }
             }
 
-            if (_steps == ESteps.CreateDownloadCenter)
+            if (_steps == ESteps.CreateDownloadScheduler)
             {
                 // 注意：下载中心作为独立任务运行！
-                if (_fileSystem.DownloadCenter == null)
+                if (_fileSystem.DownloadScheduler == null)
                 {
-                    _fileSystem.DownloadCenter = new DownloadCenterOperation(_fileSystem);
-                    OperationSystem.StartOperation(_fileSystem.PackageName, _fileSystem.DownloadCenter);
+                    _fileSystem.DownloadScheduler = new DownloadSchedulerOperation(_fileSystem);
+                    OperationSystem.StartOperation(_fileSystem.PackageName, _fileSystem.DownloadScheduler);
                 }
 
                 _steps = ESteps.Done;

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/DCFSLoadBundleOperation.cs

@@ -320,11 +320,11 @@ namespace YooAsset
                             File.Move(recordFileElement.DataFilePath, filePath);
                             _steps = ESteps.LoadCacheRawBundle;
                         }
-                        catch (Exception e)
+                        catch (Exception ex)
                         {
                             _steps = ESteps.Done;
                             Status = EOperationStatus.Failed;
-                            Error = $"Faild rename raw data file : {e.Message}";
+                            Error = $"Faild rename raw data file : {ex.Message}";
                         }
                     }
                     else

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/ClearCacheBundleFilesByLocationsOperaiton.cs

@@ -0,0 +1,142 @@
+using System.Collections.Generic;
+
+namespace YooAsset
+{
+    internal class ClearCacheBundleFilesByLocationsOperaiton : FSClearCacheFilesOperation
+    {
+        private enum ESteps
+        {
+            None,
+            CheckManifest,
+            CheckArgs,
+            GetClearCacheFiles,
+            ClearFilterCacheFiles,
+            Done,
+        }
+
+        private readonly DefaultCacheFileSystem _fileSystem;
+        private readonly PackageManifest _manifest;
+        private readonly object _clearParam;
+        private string[] _locations;
+        private List<string> _clearBundleGUIDs;
+        private int _clearFileTotalCount = 0;
+        private ESteps _steps = ESteps.None;
+
+        internal ClearCacheBundleFilesByLocationsOperaiton(DefaultCacheFileSystem fileSystem, PackageManifest manifest, object clearParam)
+        {
+            _fileSystem = fileSystem;
+            _manifest = manifest;
+            _clearParam = clearParam;
+        }
+
+        internal override void InternalStart()
+        {
+            _steps = ESteps.CheckManifest;
+        }
+
+        internal override void InternalUpdate()
+        {
+            if (_steps == ESteps.None || _steps == ESteps.Done)
+                return;
+
+            if (_steps == ESteps.CheckManifest)
+            {
+                if (_manifest == null)
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = "Can not found active package manifest !";
+                }
+                else
+                {
+                    _steps = ESteps.CheckArgs;
+                }
+            }
+
+            if (_steps == ESteps.CheckArgs)
+            {
+                if (_clearParam == null)
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = "Clear param is null !";
+                    return;
+                }
+
+                if (_clearParam is string)
+                {
+                    _locations = new string[] { _clearParam as string };
+                }
+                else if (_clearParam is List<string>)
+                {
+                    var tempList = _clearParam as List<string>;
+                    _locations = tempList.ToArray();
+                }
+                else if (_clearParam is string[])
+                {
+                    _locations = _clearParam as string[];
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = $"Invalid clear param : {_clearParam.GetType().FullName}";
+                    return;
+                }
+
+                _steps = ESteps.GetClearCacheFiles;
+            }
+
+            if (_steps == ESteps.GetClearCacheFiles)
+            {
+                _clearBundleGUIDs = GetBundleGUIDsByLocation();
+                _clearFileTotalCount = _clearBundleGUIDs.Count;
+                _steps = ESteps.ClearFilterCacheFiles;
+            }
+
+            if (_steps == ESteps.ClearFilterCacheFiles)
+            {
+                for (int i = _clearBundleGUIDs.Count - 1; i >= 0; i--)
+                {
+                    string bundleGUID = _clearBundleGUIDs[i];
+                    _fileSystem.DeleteCacheBundleFile(bundleGUID);
+                    _clearBundleGUIDs.RemoveAt(i);
+                    if (OperationSystem.IsBusy)
+                        break;
+                }
+
+                if (_clearFileTotalCount == 0)
+                    Progress = 1.0f;
+                else
+                    Progress = 1.0f - (_clearBundleGUIDs.Count / _clearFileTotalCount);
+
+                if (_clearBundleGUIDs.Count == 0)
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Succeed;
+                }
+            }
+        }
+
+        private List<string> GetBundleGUIDsByLocation()
+        {
+            List<string> result = new List<string>(_locations.Length);
+
+            foreach (var location in _locations)
+            {
+                string assetPath = _manifest.TryMappingToAssetPath(location);
+                if (_manifest.TryGetPackageAsset(assetPath, out PackageAsset packageAsset))
+                {
+                    PackageBundle bundle = _manifest.GetMainPackageBundle(packageAsset.BundleID);
+
+                    if (bundle != null)
+                    {
+                        result.Add(bundle.BundleGUID);
+                    }
+                }
+            }
+
+            return result;
+        }
+    }
+}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/ClearCacheBundleFilesByLocationsOperaiton.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 0be6ffd570645bf4a95126958a8e8a86
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/DownloadCenterOperation.cs

@@ -1,133 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace YooAsset
-{
-    internal class DownloadCenterOperation : AsyncOperationBase
-    {
-        private readonly DefaultCacheFileSystem _fileSystem;
-        protected readonly Dictionary<string, UnityDownloadFileOperation> _downloaders = new Dictionary<string, UnityDownloadFileOperation>(1000);
-        protected readonly List<string> _removeList = new List<string>(1000);
-
-        public DownloadCenterOperation(DefaultCacheFileSystem fileSystem)
-        {
-            _fileSystem = fileSystem;
-        }
-        internal override void InternalStart()
-        {
-        }
-        internal override void InternalUpdate()
-        {
-            // 获取可移除的下载器集合
-            _removeList.Clear();
-            foreach (var valuePair in _downloaders)
-            {
-                var downloader = valuePair.Value;
-                downloader.UpdateOperation();
-                if (downloader.IsDone)
-                {
-                    _removeList.Add(valuePair.Key);
-                    continue;
-                }
-
-                // 注意：主动终止引用计数为零的下载任务
-                if (downloader.RefCount <= 0)
-                {
-                    _removeList.Add(valuePair.Key);
-                    downloader.AbortOperation();
-                    continue;
-                }
-            }
-
-            // 移除下载器
-            foreach (var key in _removeList)
-            {
-                if (_downloaders.TryGetValue(key, out var downloader))
-                {
-                    Childs.Remove(downloader);
-                    _downloaders.Remove(key);
-                }
-            }
-
-            // 最大并发数检测
-            int processCount = GetProcessingOperationCount();
-            if (processCount != _downloaders.Count)
-            {
-                if (processCount < _fileSystem.DownloadMaxConcurrency)
-                {
-                    int startCount = _fileSystem.DownloadMaxConcurrency - processCount;
-                    if (startCount > _fileSystem.DownloadMaxRequestPerFrame)
-                        startCount = _fileSystem.DownloadMaxRequestPerFrame;
-
-                    foreach (var operationPair in _downloaders)
-                    {
-                        var operation = operationPair.Value;
-                        if (operation.Status == EOperationStatus.None)
-                        {
-                            operation.StartOperation();
-                            startCount--;
-                            if (startCount <= 0)
-                                break;
-                        }
-                    }
-                }
-            }
-        }
-
-        /// <summary>
-        /// 创建下载任务
-        /// </summary>
-        public UnityDownloadFileOperation DownloadFileAsync(PackageBundle bundle, string url)
-        {
-            // 查询旧的下载器
-            if (_downloaders.TryGetValue(bundle.BundleGUID, out var oldDownloader))
-            {
-                oldDownloader.Reference();
-                return oldDownloader;
-            }
-
-            // 创建新的下载器
-            UnityDownloadFileOperation newDownloader;
-            bool isRequestLocalFile = DownloadSystemHelper.IsRequestLocalFile(url);
-            if (isRequestLocalFile)
-            {
-                newDownloader = new UnityDownloadLocalFileOperation(_fileSystem, bundle, url);
-                AddChildOperation(newDownloader);
-                _downloaders.Add(bundle.BundleGUID, newDownloader);
-            }
-            else
-            {
-                if (bundle.FileSize >= _fileSystem.ResumeDownloadMinimumSize)
-                {
-                    newDownloader = new UnityDownloadResumeFileOperation(_fileSystem, bundle, url);
-                    AddChildOperation(newDownloader);
-                    _downloaders.Add(bundle.BundleGUID, newDownloader);
-                }
-                else
-                {
-                    newDownloader = new UnityDownloadNormalFileOperation(_fileSystem, bundle, url);
-                    AddChildOperation(newDownloader);
-                    _downloaders.Add(bundle.BundleGUID, newDownloader);
-                }
-            }
-
-            newDownloader.Reference();
-            return newDownloader;
-        }
-
-        /// <summary>
-        /// 获取正在进行中的下载器总数
-        /// </summary>
-        private int GetProcessingOperationCount()
-        {
-            int count = 0;
-            foreach (var operationPair in _downloaders)
-            {
-                var operation = operationPair.Value;
-                if (operation.Status != EOperationStatus.None)
-                    count++;
-            }
-            return count;
-        }
-    }
-}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/DownloadCenterOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 768ef2df3433df245a26fec28d022e45
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/DownloadPackageBundleOperation.cs

@@ -1,4 +1,5 @@
-using UnityEngine;
+using System.IO;
+using UnityEngine;
 
 namespace YooAsset
 {
@@ -17,10 +18,10 @@ namespace YooAsset
         // 下载参数
         protected readonly DefaultCacheFileSystem _fileSystem;
         protected readonly DownloadFileOptions _options;
-        private UnityDownloadFileOperation _unityDownloadFileOp;
+        private DownloadAndCacheFileOperation _downloadFileOp;
 
         protected int _requestCount = 0;
-        protected float _tryAgainTimer;
+        protected float _tryAgainTimer = 0;
         protected int _failedTryAgain;
         private ESteps _steps = ESteps.None;
 
@@ -67,7 +68,7 @@ namespace YooAsset
                 }
 
                 string url = GetRequestURL();
-                _unityDownloadFileOp = _fileSystem.DownloadCenter.DownloadFileAsync(Bundle, url);
+                _downloadFileOp = _fileSystem.DownloadScheduler.DownloadAndCacheFileAsync(Bundle, url);
                 _steps = ESteps.CheckRequest;
             }
 
@@ -75,20 +76,16 @@ namespace YooAsset
             if (_steps == ESteps.CheckRequest)
             {
                 if (IsWaitForAsyncComplete)
-                    _unityDownloadFileOp.WaitForAsyncComplete();
+                    _downloadFileOp.WaitForAsyncComplete();
 
-                // 因为并发数量限制，下载器可能被挂起！
-                if (_unityDownloadFileOp.Status == EOperationStatus.None)
+                _downloadFileOp.UpdateOperation();
+                Progress = _downloadFileOp.Progress;
+                DownloadedBytes = _downloadFileOp.DownloadedBytes;
+                DownloadProgress = _downloadFileOp.DownloadProgress;
+                if (_downloadFileOp.IsDone == false)
                     return;
 
-                _unityDownloadFileOp.UpdateOperation();
-                Progress = _unityDownloadFileOp.Progress;
-                DownloadedBytes = _unityDownloadFileOp.DownloadedBytes;
-                DownloadProgress = _unityDownloadFileOp.DownloadProgress;
-                if (_unityDownloadFileOp.IsDone == false)
-                    return;
-
-                if (_unityDownloadFileOp.Status == EOperationStatus.Succeed)
+                if (_downloadFileOp.Status == EOperationStatus.Succeed)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;
@@ -98,13 +95,13 @@ namespace YooAsset
                     if (IsWaitForAsyncComplete == false && _failedTryAgain > 0)
                     {
                         _steps = ESteps.TryAgain;
-                        YooLogger.Warning($"Failed download : {_unityDownloadFileOp.URL} Try again !");
+                        YooLogger.Warning($"Failed download : {_downloadFileOp.URL} Try again !");
                     }
                     else
                     {
                         _steps = ESteps.Done;
                         Status = EOperationStatus.Failed;
-                        Error = _unityDownloadFileOp.Error;
+                        Error = _downloadFileOp.Error;
                         YooLogger.Error(Error);
                     }
                 }
@@ -141,9 +138,9 @@ namespace YooAsset
             // 注意：取消下载任务的时候引用计数减一
             if (_steps != ESteps.Done)
             {
-                if (_unityDownloadFileOp != null)
+                if (_downloadFileOp != null)
                 {
-                    _unityDownloadFileOp.Release();
+                    _downloadFileOp.Release();
                 }
             }
         }

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/DownloadPackageHashOperation.cs

@@ -15,7 +15,7 @@ namespace YooAsset
         private readonly DefaultCacheFileSystem _fileSystem;
         private readonly string _packageVersion;
         private readonly int _timeout;
-        private UnityWebFileRequestOperation _webFileRequestOp;
+        private IDownloadFileRequest _webFileRequestOp;
         private int _requestCount = 0;
         private ESteps _steps = ESteps.None;
 
@@ -57,16 +57,16 @@ namespace YooAsset
                     string savePath = _fileSystem.GetCachePackageHashFilePath(_packageVersion);
                     string fileName = YooAssetSettingsData.GetPackageHashFileName(_fileSystem.PackageName, _packageVersion);
                     string webURL = GetWebRequestURL(fileName);
-                    _webFileRequestOp = new UnityWebFileRequestOperation(webURL, savePath, _timeout);
-                    _webFileRequestOp.StartOperation();
-                    AddChildOperation(_webFileRequestOp);
+                    int watchdogTime = _fileSystem.DownloadWatchDogTime;
+                    var args = new DownloadFileRequestArgs(webURL, savePath, _timeout, watchdogTime);
+                    _webFileRequestOp = _fileSystem.DownloadBackend.CreateFileRequest(args);
+                    _webFileRequestOp.SendRequest();
                 }
 
-                _webFileRequestOp.UpdateOperation();
                 if (_webFileRequestOp.IsDone == false)
                     return;
 
-                if (_webFileRequestOp.Status == EOperationStatus.Succeed)
+                if (_webFileRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/DownloadPackageManifestOperation.cs

@@ -15,7 +15,7 @@ namespace YooAsset
         private readonly DefaultCacheFileSystem _fileSystem;
         private readonly string _packageVersion;
         private readonly int _timeout;
-        private UnityWebFileRequestOperation _webFileRequestOp;
+        private IDownloadFileRequest _webFileRequestOp;
         private int _requestCount = 0;
         private ESteps _steps = ESteps.None;
 
@@ -57,16 +57,16 @@ namespace YooAsset
                     string savePath = _fileSystem.GetCachePackageManifestFilePath(_packageVersion);
                     string fileName = YooAssetSettingsData.GetManifestBinaryFileName(_fileSystem.PackageName, _packageVersion);
                     string webURL = GetDownloadRequestURL(fileName);
-                    _webFileRequestOp = new UnityWebFileRequestOperation(webURL, savePath, _timeout);
-                    _webFileRequestOp.StartOperation();
-                    AddChildOperation(_webFileRequestOp);
+                    int watchdogTime = _fileSystem.DownloadWatchDogTime;
+                    var args = new DownloadFileRequestArgs(webURL, savePath, _timeout, watchdogTime);
+                    _webFileRequestOp = _fileSystem.DownloadBackend.CreateFileRequest(args);
+                    _webFileRequestOp.SendRequest();
                 }
 
-                _webFileRequestOp.UpdateOperation();
                 if (_webFileRequestOp.IsDone == false)
                     return;
 
-                if (_webFileRequestOp.Status == EOperationStatus.Succeed)
+                if (_webFileRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/RequestRemotePackageVersionOperation.cs

@@ -13,7 +13,7 @@ namespace YooAsset
         private readonly DefaultCacheFileSystem _fileSystem;
         private readonly bool _appendTimeTicks;
         private readonly int _timeout;
-        private UnityWebTextRequestOperation _webTextRequestOp;
+        private IDownloadTextRequest _webTextRequestOp;
         private int _requestCount = 0;
         private ESteps _steps = ESteps.None;
 
@@ -45,17 +45,17 @@ namespace YooAsset
                 {
                     string fileName = YooAssetSettingsData.GetPackageVersionFileName(_fileSystem.PackageName);
                     string url = GetWebRequestURL(fileName);
-                    _webTextRequestOp = new UnityWebTextRequestOperation(url, _timeout);
-                    _webTextRequestOp.StartOperation();
-                    AddChildOperation(_webTextRequestOp);
+                    int watchDogTime = _fileSystem.DownloadWatchDogTime;
+                    var args = new DownloadDataRequestArgs(url, _timeout, watchDogTime);
+                    _webTextRequestOp = _fileSystem.DownloadBackend.CreateTextRequest(args);
+                    _webTextRequestOp.SendRequest();
                 }
 
-                _webTextRequestOp.UpdateOperation();
-                Progress = _webTextRequestOp.Progress;
+                Progress = _webTextRequestOp.DownloadProgress;
                 if (_webTextRequestOp.IsDone == false)
                     return;
 
-                if (_webTextRequestOp.Status == EOperationStatus.Succeed)
+                if (_webTextRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     PackageVersion = _webTextRequestOp.Result;
                     if (string.IsNullOrEmpty(PackageVersion))

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler.meta

@@ -0,0 +1,8 @@
+fileFormatVersion: 2
+guid: bf9991076b60f0f459846f54b0ca6698
+folderAsset: yes
+DefaultImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheFileOperation.cs

@@ -0,0 +1,51 @@
+
+namespace YooAsset
+{
+    internal abstract class DownloadAndCacheFileOperation : AsyncOperationBase
+    {
+        /// <summary>
+        /// 引用计数
+        /// </summary>
+        public int RefCount { private set; get; }
+
+        /// <summary>
+        /// 下载地址
+        /// </summary>
+        public readonly string URL;
+
+        /// <summary>
+        /// 下载进度
+        /// </summary>
+        public float DownloadProgress { get; protected set; }
+
+        /// <summary>
+        /// 下载字节
+        /// </summary>
+        public long DownloadedBytes { get; protected set; }
+
+        public DownloadAndCacheFileOperation(string url)
+        {
+            URL = url;
+        }
+        internal override string InternalGetDesc()
+        {
+            return $"RefCount : {RefCount}";
+        }
+
+        /// <summary>
+        /// 减少引用计数
+        /// </summary>
+        public void Release()
+        {
+            RefCount--;
+        }
+
+        /// <summary>
+        /// 增加引用计数
+        /// </summary>
+        public void Reference()
+        {
+            RefCount++;
+        }
+    }
+}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheFileOperation.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 2954a64fd419d5a4b9d0a102260d193c
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheLocalFileOperation.cs

@@ -1,94 +1,79 @@
 using System.IO;
-using UnityEngine;
-using UnityEngine.Networking;
 
 namespace YooAsset
 {
-    internal sealed class UnityDownloadLocalFileOperation : UnityDownloadFileOperation
+    internal sealed class DownloadAndCacheLocalFileOperation : DownloadAndCacheFileOperation
     {
+        private enum ESteps
+        {
+            None,
+            CheckCopy,
+            CopyLocalFile,
+            CreateRequest,
+            CheckRequest,
+            VerifyBundleFile,
+            CacheBundleFile,
+            Done,
+        }
+
+        private readonly DefaultCacheFileSystem _fileSystem;
+        private readonly PackageBundle _bundle;
+        private readonly string _tempFilePath;
+        private IDownloadRequest _request;
         private VerifyTempFileOperation _verifyOperation;
         private ESteps _steps = ESteps.None;
 
-        internal UnityDownloadLocalFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url)
-            : base(fileSystem, bundle, url)
+        internal DownloadAndCacheLocalFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url) : base(url)
         {
+            _fileSystem = fileSystem;
+            _bundle = bundle;
+            _tempFilePath = _fileSystem.GetTempFilePath(_bundle);
         }
         internal override void InternalStart()
         {
-            if (_fileSystem.CopyLocalFileServices != null)
-                _steps = ESteps.CopyLocalFile;
-            else
-                _steps = ESteps.CreateRequest;
+            _steps = ESteps.CheckCopy;
         }
         internal override void InternalUpdate()
         {
             if (_steps == ESteps.None || _steps == ESteps.Done)
                 return;
 
-            // 创建下载器
-            if (_steps == ESteps.CreateRequest)
+            // 检测文件拷贝
+            if (_steps == ESteps.CheckCopy)
             {
+                // 删除历史缓存文件
                 FileUtility.CreateFileDirectory(_tempFilePath);
                 if (File.Exists(_tempFilePath))
                     File.Delete(_tempFilePath);
 
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            // 检测下载结果
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = DownloadProgress;
-
-                UpdateWatchDog();
-                if (_webRequest.isDone == false)
-                    return;
-
-                // 检查网络错误
-                if (CheckRequestResult())
-                {
-                    _steps = ESteps.VerifyFile;
-                }
+                if (_fileSystem.CopyLocalFileServices != null)
+                    _steps = ESteps.CopyLocalFile;
                 else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
+                    _steps = ESteps.CreateRequest;
             }
 
-            // 拷贝内置文件
+            // 拷贝本地文件
             if (_steps == ESteps.CopyLocalFile)
             {
-                FileUtility.CreateFileDirectory(_tempFilePath);
-                if (File.Exists(_tempFilePath))
-                    File.Delete(_tempFilePath);
-
                 try
                 {
                     //TODO 团结引擎，在某些机型（红米），拷贝包内文件会小概率失败！需要借助其它方式来拷贝包内文件。
                     var localFileInfo = new LocalFileInfo();
                     localFileInfo.PackageName = _fileSystem.PackageName;
                     localFileInfo.BundleName = _bundle.BundleName;
-                    localFileInfo.SourceFileURL = _requestURL;
+                    localFileInfo.SourceFileURL = URL;
                     _fileSystem.CopyLocalFileServices.CopyFile(localFileInfo, _tempFilePath);
                     if (File.Exists(_tempFilePath))
                     {
                         DownloadProgress = 1f;
                         DownloadedBytes = _bundle.FileSize;
-                        Progress = DownloadProgress;
-                        _steps = ESteps.VerifyFile;
+                        _steps = ESteps.VerifyBundleFile;
                     }
                     else
                     {
                         _steps = ESteps.Done;
                         Status = EOperationStatus.Failed;
-                        Error = $"Failed copy local file : {_requestURL}";
+                        Error = $"Failed copy local file : {URL}";
                     }
                 }
                 catch (System.Exception ex)
@@ -99,8 +84,44 @@ namespace YooAsset
                 }
             }
 
-            // 验证下载文件
-            if (_steps == ESteps.VerifyFile)
+            // 创建下载请求
+            if (_steps == ESteps.CreateRequest)
+            {
+                int watchdogTime = _fileSystem.DownloadWatchDogTime;
+                int timeout = 0; //注意：文件下载不做超时检测
+                var args = new DownloadFileRequestArgs(URL, _tempFilePath, timeout, watchdogTime);
+                _request = _fileSystem.DownloadBackend.CreateFileRequest(args);
+                _request.SendRequest();
+                _steps = ESteps.CheckRequest;
+            }
+
+            // 检测下载结果
+            if (_steps == ESteps.CheckRequest)
+            {
+                DownloadProgress = _request.DownloadProgress;
+                DownloadedBytes = _request.DownloadedBytes;
+                Progress = DownloadProgress;
+                if (_request.IsDone == false)
+                    return;
+
+                // 检查网络错误
+                if (_request.Status == EDownloadRequestStatus.Succeed)
+                {
+                    _steps = ESteps.VerifyBundleFile;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = _request.Error;
+                }
+
+                // 最终释放请求器
+                _request.Dispose();
+            }
+
+            // 验证下载结果
+            if (_steps == ESteps.VerifyBundleFile)
             {
                 if (_verifyOperation == null)
                 {
@@ -119,35 +140,51 @@ namespace YooAsset
 
                 if (_verifyOperation.Status == EOperationStatus.Succeed)
                 {
-                    if (_fileSystem.WriteCacheBundleFile(_bundle, _tempFilePath))
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Succeed;
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"{_fileSystem.GetType().FullName} failed to write file !";
-                    }
+                    _steps = ESteps.CacheBundleFile;
                 }
                 else
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Failed;
                     Error = _verifyOperation.Error;
+
+                    // 注意：验证失败后直接删除文件
+                    if (File.Exists(_tempFilePath))
+                        File.Delete(_tempFilePath);
+                }
+            }
+
+            // 缓存文件
+            if (_steps == ESteps.CacheBundleFile)
+            {
+                if (_fileSystem.WriteCacheBundleFile(_bundle, _tempFilePath))
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Succeed;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = $"{_fileSystem.GetType().FullName} failed to write file !";
                 }
 
-                // 注意：验证完成后直接删除文件
+                // 注意：缓存完成后直接删除临时文件
                 if (File.Exists(_tempFilePath))
                     File.Delete(_tempFilePath);
             }
         }
+        internal override void InternalAbort()
+        {
+            if (_request != null)
+                _request.AbortRequest();
+        }
         internal override void InternalWaitForAsyncComplete()
         {
             while (true)
             {
                 //TODO 等待导入或解压本地文件完毕，该操作会挂起主线程！
+                _fileSystem.DownloadBackend.Update();
                 InternalUpdate();
                 if (IsDone)
                     break;
@@ -156,15 +193,5 @@ namespace YooAsset
                 System.Threading.Thread.Sleep(1);
             }
         }
-
-        private void CreateWebRequest()
-        {
-            DownloadHandlerFile handler = new DownloadHandlerFile(_tempFilePath);
-            handler.removeFileOnAbort = true;
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _webRequest.SendWebRequest();
-        }
     }
 }

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheLocalFileOperation.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 47700ac672942834f8d5a7c59783d88e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheRemoteFileOperation.cs

@@ -0,0 +1,206 @@
+using System.IO;
+
+namespace YooAsset
+{
+    internal sealed class DownloadAndCacheRemoteFileOperation : DownloadAndCacheFileOperation
+    {
+        private enum ESteps
+        {
+            None,
+            CreateRequest,
+            CheckRequest,
+            VerifyBundleFile,
+            CacheBundleFile,
+            Done,
+        }
+
+        private readonly DefaultCacheFileSystem _fileSystem;
+        private readonly PackageBundle _bundle;
+        private readonly string _tempFilePath;
+        private bool _enableResume = false;
+        private long _fileOriginLength = 0;
+        private IDownloadRequest _request;
+        private VerifyTempFileOperation _verifyOperation;
+        private ESteps _steps = ESteps.None;
+
+        internal DownloadAndCacheRemoteFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url) : base(url)
+        {
+            _fileSystem = fileSystem;
+            _bundle = bundle;
+            _tempFilePath = _fileSystem.GetTempFilePath(_bundle);
+        }
+        internal override void InternalStart()
+        {
+            _steps = ESteps.CreateRequest;
+        }
+        internal override void InternalUpdate()
+        {
+            if (_steps == ESteps.None || _steps == ESteps.Done)
+                return;
+
+            // 创建下载请求
+            if (_steps == ESteps.CreateRequest)
+            {
+                FileUtility.CreateFileDirectory(_tempFilePath);
+
+                _enableResume = _bundle.FileSize >= _fileSystem.ResumeDownloadMinimumSize;
+                if (_enableResume)
+                {
+                    _request = CreateResumeRequest();
+                    _request.SendRequest();
+                    _steps = ESteps.CheckRequest;
+                }
+                else
+                {
+                    _request = CreateNormalRequest();
+                    _request.SendRequest();
+                    _steps = ESteps.CheckRequest;
+                }
+            }
+
+            // 检测下载结果
+            if (_steps == ESteps.CheckRequest)
+            {
+                DownloadProgress = _request.DownloadProgress;
+                DownloadedBytes = _fileOriginLength + _request.DownloadedBytes;
+                Progress = DownloadProgress;
+                if (_request.IsDone == false)
+                    return;
+
+                // 检查网络错误
+                if (_request.Status == EDownloadRequestStatus.Succeed)
+                {
+                    _steps = ESteps.VerifyBundleFile;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = _request.Error;
+                }
+
+                // 在遇到特殊错误的时候删除文件
+                if (_enableResume)
+                    ClearTempFileWhenError(_request.HttpCode);
+
+                // 最终释放请求器
+                _request.Dispose();
+            }
+
+            // 验证下载结果
+            if (_steps == ESteps.VerifyBundleFile)
+            {
+                if (_verifyOperation == null)
+                {
+                    var element = new TempFileElement(_tempFilePath, _bundle.FileCRC, _bundle.FileSize);
+                    _verifyOperation = new VerifyTempFileOperation(element);
+                    _verifyOperation.StartOperation();
+                    AddChildOperation(_verifyOperation);
+                }
+
+                if (IsWaitForAsyncComplete)
+                    _verifyOperation.WaitForAsyncComplete();
+
+                _verifyOperation.UpdateOperation();
+                if (_verifyOperation.IsDone == false)
+                    return;
+
+                if (_verifyOperation.Status == EOperationStatus.Succeed)
+                {
+                    _steps = ESteps.CacheBundleFile;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = _verifyOperation.Error;
+
+                    // 注意：验证失败后直接删除文件
+                    if (File.Exists(_tempFilePath))
+                        File.Delete(_tempFilePath);
+                }
+            }
+
+            // 缓存文件
+            if (_steps == ESteps.CacheBundleFile)
+            {
+                if (_fileSystem.WriteCacheBundleFile(_bundle, _tempFilePath))
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Succeed;
+                }
+                else
+                {
+                    _steps = ESteps.Done;
+                    Status = EOperationStatus.Failed;
+                    Error = $"{_fileSystem.GetType().FullName} failed to write file !";
+                }
+
+                // 注意：缓存完成后直接删除临时文件
+                if (File.Exists(_tempFilePath))
+                    File.Delete(_tempFilePath);
+            }
+        }
+        internal override void InternalAbort()
+        {
+            if (_request != null)
+                _request.AbortRequest();
+        }
+        internal override void InternalWaitForAsyncComplete()
+        {
+            if (_steps != ESteps.Done)
+            {
+                // 注意：不中断下载任务，保持后台继续下载
+                YooLogger.Error($"Try load bundle {_bundle.BundleName} from remote : {URL} !");
+            }
+        }
+
+        private IDownloadRequest CreateResumeRequest()
+        {
+            // 获取下载起始位置
+            if (File.Exists(_tempFilePath))
+            {
+                FileInfo fileInfo = new FileInfo(_tempFilePath);
+                if (fileInfo.Length >= _bundle.FileSize)
+                {
+                    File.Delete(_tempFilePath);
+                }
+                else
+                {
+                    _fileOriginLength = fileInfo.Length;
+                }
+            }
+
+            int watchdogTime = _fileSystem.DownloadWatchDogTime;
+            int timeout = 0; //注意：文件下载不做超时检测
+            bool appendToFile = true;
+            bool removeFileOnAbort = false;
+            long resumeFromBytes = _fileOriginLength;
+            var args = new DownloadFileRequestArgs(URL, _tempFilePath, timeout, watchdogTime, appendToFile, removeFileOnAbort, resumeFromBytes);
+            return _fileSystem.DownloadBackend.CreateFileRequest(args);
+        }
+        private IDownloadRequest CreateNormalRequest()
+        {
+            // 删除历史缓存文件
+            if (File.Exists(_tempFilePath))
+                File.Delete(_tempFilePath);
+
+            int watchdogTime = _fileSystem.DownloadWatchDogTime;
+            int timeout = 0; //注意：文件下载不做超时检测
+            var args = new DownloadFileRequestArgs(URL, _tempFilePath, timeout, watchdogTime);
+            return _fileSystem.DownloadBackend.CreateFileRequest(args);
+        }
+        private void ClearTempFileWhenError(long httpCode)
+        {
+            if (_fileSystem.ResumeDownloadResponseCodes == null)
+                return;
+
+            //说明：如果遇到以下错误返回码，验证失败直接删除文件
+            if (_fileSystem.ResumeDownloadResponseCodes.Contains(httpCode))
+            {
+                if (File.Exists(_tempFilePath))
+                    File.Delete(_tempFilePath);
+            }
+        }
+    }
+}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadAndCacheRemoteFileOperation.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: ad910a81855976e44b4f1f09051910b0
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadSchedulerOperation.cs

@@ -0,0 +1,185 @@
+using System;
+using System.Collections.Generic;
+
+namespace YooAsset
+{
+    /// <summary>
+    /// 下载调度器
+    /// </summary>
+    /// <remarks>
+    /// 管理所有活跃的下载任务，控制并发数量。
+    /// </remarks>
+    internal class DownloadSchedulerOperation : AsyncOperationBase, IDisposable
+    {
+        private readonly DefaultCacheFileSystem _fileSystem;
+        private readonly Dictionary<string, DownloadAndCacheFileOperation> _downloaders = new Dictionary<string, DownloadAndCacheFileOperation>(1000);
+        private readonly List<string> _removeList = new List<string>(1000);
+
+        /// <summary>
+        /// 是否已暂停
+        /// </summary>
+        public bool Paused { get; private set; } = false;
+
+        /// <summary>
+        /// 当前活跃的下载任务数
+        /// </summary>
+        public int ActiveDownloadCount { get; private set; }
+
+        /// <summary>
+        /// 当前等待中的下载任务数
+        /// </summary>
+        public int PendingDownloadCount
+        {
+            get
+            {
+                return _downloaders.Count - ActiveDownloadCount;
+            }
+        }
+
+
+        /// <summary>
+        /// 构造下载中心
+        /// </summary>
+        public DownloadSchedulerOperation(DefaultCacheFileSystem fileSystem)
+        {
+            _fileSystem = fileSystem;
+        }
+        internal override void InternalStart()
+        {
+        }
+        internal override void InternalUpdate()
+        {
+            // 驱动下载后台
+            _fileSystem.DownloadBackend.Update();
+
+            // 获取可移除的下载器集合
+            _removeList.Clear();
+            foreach (var valuePair in _downloaders)
+            {
+                var downloader = valuePair.Value;
+                downloader.UpdateOperation();
+                if (downloader.IsDone)
+                {
+                    _removeList.Add(valuePair.Key);
+                    continue;
+                }
+
+                // 注意：主动终止引用计数为零的下载任务
+                if (downloader.RefCount <= 0)
+                {
+                    _removeList.Add(valuePair.Key);
+                    downloader.AbortOperation();
+                    continue;
+                }
+            }
+
+            // 移除下载器
+            foreach (var key in _removeList)
+            {
+                if (_downloaders.TryGetValue(key, out var downloader))
+                {
+                    RemoveChildOperation(downloader);
+                    _downloaders.Remove(key);
+                }
+            }
+
+            // 暂停时不启动新任务
+            if (Paused)
+                return;
+
+            // 最大并发数检测
+            ActiveDownloadCount = GetProcessingOperationCount();
+            if (ActiveDownloadCount != _downloaders.Count)
+            {
+                int maxConcurrency = _fileSystem.DownloadMaxConcurrency;
+                int maxRequestPerFrame = _fileSystem.DownloadMaxRequestPerFrame;
+                if (ActiveDownloadCount < maxConcurrency)
+                {
+                    int startCount = maxConcurrency - ActiveDownloadCount;
+                    if (startCount > maxRequestPerFrame)
+                        startCount = maxRequestPerFrame;
+
+                    foreach (var operationPair in _downloaders)
+                    {
+                        var operation = operationPair.Value;
+                        if (operation.Status == EOperationStatus.None)
+                        {
+                            operation.StartOperation();
+                            startCount--;
+                            if (startCount <= 0)
+                                break;
+                        }
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// 中止所有下载任务
+        /// </summary>
+        public void AbortAll()
+        {
+            foreach (var valuePair in _downloaders)
+            {
+                valuePair.Value.AbortOperation();
+            }
+            _downloaders.Clear();
+        }
+
+        /// <summary>
+        /// 释放资源
+        /// </summary>
+        public void Dispose()
+        {
+            AbortAll();
+        }
+
+        /// <summary>
+        /// 创建下载任务
+        /// </summary>
+        /// <param name="bundle">资源包信息</param>
+        /// <param name="url">下载地址</param>
+        /// <returns>下载操作</returns>
+        public DownloadAndCacheFileOperation DownloadAndCacheFileAsync(PackageBundle bundle, string url)
+        {
+            // 查询旧的下载器
+            if (_downloaders.TryGetValue(bundle.BundleGUID, out var oldDownloader))
+            {
+                oldDownloader.Reference();
+                return oldDownloader;
+            }
+
+            // 创建新的下载器
+            DownloadAndCacheFileOperation newDownloader;
+            bool isRequestLocalFile = DownloadSystemHelper.IsRequestLocalFile(url);
+            if (isRequestLocalFile)
+            {
+                newDownloader = new DownloadAndCacheLocalFileOperation(_fileSystem, bundle, url);
+            }
+            else
+            {
+                newDownloader = new DownloadAndCacheRemoteFileOperation(_fileSystem, bundle, url);
+            }
+
+            AddChildOperation(newDownloader);
+            _downloaders.Add(bundle.BundleGUID, newDownloader);
+            newDownloader.Reference();
+            return newDownloader;
+        }
+
+        /// <summary>
+        /// 获取正在进行中的下载器总数
+        /// </summary>
+        private int GetProcessingOperationCount()
+        {
+            int count = 0;
+            foreach (var operationPair in _downloaders)
+            {
+                var operation = operationPair.Value;
+                if (operation.Status != EOperationStatus.None)
+                    count++;
+            }
+            return count;
+        }
+    }
+}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/Scheduler/DownloadSchedulerOperation.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 73441e829c36a36418f5d677e189e9f3
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadFileOperation.cs

@@ -1,98 +0,0 @@
-
-namespace YooAsset
-{
-    internal abstract class UnityDownloadFileOperation : UnityWebRequestOperation
-    {
-        protected enum ESteps
-        {
-            None,
-            CreateRequest,
-            Download,
-            CopyLocalFile,
-            VerifyFile,
-            Done,
-        }
-
-        protected readonly DefaultCacheFileSystem _fileSystem;
-        protected readonly PackageBundle _bundle;
-        protected readonly string _tempFilePath;
-
-        private bool _watchDogInit = false;
-        private bool _watchDogAborted = false;
-        private ulong _lastDownloadBytes;
-        private double _lastGetDataTime;
-
-        /// <summary>
-        /// 引用计数
-        /// </summary>
-        public int RefCount { private set; get; }
-
-        internal UnityDownloadFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url) : base(url)
-        {
-            _fileSystem = fileSystem;
-            _bundle = bundle;
-            _tempFilePath = _fileSystem.GetTempFilePath(bundle);
-        }
-        internal override string InternalGetDesc()
-        {
-            return $"RefCount : {RefCount}";
-        }
-
-        /// <summary>
-        /// 更新看门狗监测
-        /// 说明：监控时间范围内，如果没有接收到任何下载数据，那么直接终止任务！
-        /// </summary>
-        protected void UpdateWatchDog()
-        {
-            if (_fileSystem.DownloadWatchDogTime == int.MaxValue)
-                return;
-
-            if (_watchDogAborted)
-                return;
-
-#if UNITY_2020_3_OR_NEWER
-            double realtimeSinceStartup = UnityEngine.Time.realtimeSinceStartupAsDouble;
-#else
-            double realtimeSinceStartup = UnityEngine.Time.realtimeSinceStartup;
-#endif
-
-            if (_watchDogInit == false)
-            {
-                _watchDogInit = true;
-                _lastDownloadBytes = 0;
-                _lastGetDataTime = realtimeSinceStartup;
-            }
-
-            if (_webRequest.downloadedBytes != _lastDownloadBytes)
-            {
-                _lastDownloadBytes = _webRequest.downloadedBytes;
-                _lastGetDataTime = realtimeSinceStartup;
-            }
-            else
-            {
-                double deltaTime = realtimeSinceStartup - _lastGetDataTime;
-                if (deltaTime > _fileSystem.DownloadWatchDogTime)
-                {
-                    _watchDogAborted = true;
-                    InternalAbort(); //终止网络请求
-                }
-            }
-        }
-
-        /// <summary>
-        /// 减少引用计数
-        /// </summary>
-        public void Release()
-        {
-            RefCount--;
-        }
-
-        /// <summary>
-        /// 增加引用计数
-        /// </summary>
-        public void Reference()
-        {
-            RefCount++;
-        }
-    }
-}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadFileOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 40bb5e9391f413c42ae70e48ca90c4b7
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadLocalFileOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: c68640bb1d36552469024324e3357bc2
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
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-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadNormalFileOperation.cs

@@ -1,124 +0,0 @@
-using System.IO;
-using UnityEngine;
-using UnityEngine.Networking;
-
-namespace YooAsset
-{
-    internal sealed class UnityDownloadNormalFileOperation : UnityDownloadFileOperation
-    {
-        private VerifyTempFileOperation _verifyOperation;
-        private ESteps _steps = ESteps.None;
-
-        internal UnityDownloadNormalFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url)
-            : base(fileSystem, bundle, url)
-        {
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            // 创建下载器
-            if (_steps == ESteps.CreateRequest)
-            {
-                FileUtility.CreateFileDirectory(_tempFilePath);
-                if (File.Exists(_tempFilePath))
-                    File.Delete(_tempFilePath);
-
-                CreateWebRequest();
-                _steps = ESteps.Download;
-            }
-
-            // 检测下载结果
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = (long)_webRequest.downloadedBytes;
-                Progress = DownloadProgress;
-
-                UpdateWatchDog();
-                if (_webRequest.isDone == false)
-                    return;
-
-                // 检查网络错误
-                if (CheckRequestResult())
-                {
-                    _steps = ESteps.VerifyFile;
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-
-            // 验证下载文件
-            if (_steps == ESteps.VerifyFile)
-            {
-                if (_verifyOperation == null)
-                {
-                    var element = new TempFileElement(_tempFilePath, _bundle.FileCRC, _bundle.FileSize);
-                    _verifyOperation = new VerifyTempFileOperation(element);
-                    _verifyOperation.StartOperation();
-                    AddChildOperation(_verifyOperation);
-                }
-
-                if (IsWaitForAsyncComplete)
-                    _verifyOperation.WaitForAsyncComplete();
-
-                _verifyOperation.UpdateOperation();
-                if (_verifyOperation.IsDone == false)
-                    return;
-
-                if (_verifyOperation.Status == EOperationStatus.Succeed)
-                {
-                    if (_fileSystem.WriteCacheBundleFile(_bundle, _tempFilePath))
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Succeed;
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"{_fileSystem.GetType().FullName} failed to write file ! {_tempFilePath}";
-                    }
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                    Error = _verifyOperation.Error;
-                }
-
-                // 注意：验证完成后直接删除文件
-                if (File.Exists(_tempFilePath))
-                    File.Delete(_tempFilePath);
-            }
-        }
-        internal override void InternalWaitForAsyncComplete()
-        {
-            if (_steps != ESteps.Done)
-            {
-                YooLogger.Error($"Try load bundle {_bundle.BundleName} from remote : {_requestURL} !");
-            }
-        }
-
-        private void CreateWebRequest()
-        {
-            DownloadHandlerFile handler = new DownloadHandlerFile(_tempFilePath);
-            handler.removeFileOnAbort = true;
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadNormalFileOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 759967d543776a0469b625eff171d235
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadResumeFileOperation.cs

@@ -1,158 +0,0 @@
-using System.IO;
-using UnityEngine;
-using UnityEngine.Networking;
-
-namespace YooAsset
-{
-    internal sealed class UnityDownloadResumeFileOperation : UnityDownloadFileOperation
-    {
-        private VerifyTempFileOperation _verifyOperation;
-        private long _fileOriginLength = 0;
-        private ESteps _steps = ESteps.None;
-
-        internal UnityDownloadResumeFileOperation(DefaultCacheFileSystem fileSystem, PackageBundle bundle, string url)
-            : base(fileSystem, bundle, url)
-        {
-        }
-        internal override void InternalStart()
-        {
-            _steps = ESteps.CreateRequest;
-        }
-        internal override void InternalUpdate()
-        {
-            if (_steps == ESteps.None || _steps == ESteps.Done)
-                return;
-
-            // 创建下载器
-            if (_steps == ESteps.CreateRequest)
-            {
-                FileUtility.CreateFileDirectory(_tempFilePath);
-
-                // 获取下载起始位置
-                _fileOriginLength = 0;
-                long fileBeginLength = -1;
-                if (File.Exists(_tempFilePath))
-                {
-                    FileInfo fileInfo = new FileInfo(_tempFilePath);
-                    if (fileInfo.Length >= _bundle.FileSize)
-                    {
-                        File.Delete(_tempFilePath);
-                    }
-                    else
-                    {
-                        fileBeginLength = fileInfo.Length;
-                        _fileOriginLength = fileBeginLength;
-                        DownloadedBytes = _fileOriginLength;
-                    }
-                }
-
-                CreateWebRequest(fileBeginLength);
-                _steps = ESteps.Download;
-            }
-
-            // 检测下载结果
-            if (_steps == ESteps.Download)
-            {
-                DownloadProgress = _webRequest.downloadProgress;
-                DownloadedBytes = _fileOriginLength + (long)_webRequest.downloadedBytes;
-                Progress = DownloadProgress;
-
-                UpdateWatchDog();
-                if (_webRequest.isDone == false)
-                    return;
-
-                // 检查网络错误
-                if (CheckRequestResult())
-                {
-                    _steps = ESteps.VerifyFile;
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                }
-
-                // 在遇到特殊错误的时候删除文件
-                ClearTempFileWhenError();
-
-                // 注意：最终释放请求器
-                DisposeRequest();
-            }
-
-            // 验证下载文件
-            if (_steps == ESteps.VerifyFile)
-            {
-                if (_verifyOperation == null)
-                {
-                    var element = new TempFileElement(_tempFilePath, _bundle.FileCRC, _bundle.FileSize);
-                    _verifyOperation = new VerifyTempFileOperation(element);
-                    _verifyOperation.StartOperation();
-                    AddChildOperation(_verifyOperation);
-                }
-
-                if (IsWaitForAsyncComplete)
-                    _verifyOperation.WaitForAsyncComplete();
-
-                _verifyOperation.UpdateOperation();
-                if (_verifyOperation.IsDone == false)
-                    return;
-
-                if (_verifyOperation.Status == EOperationStatus.Succeed)
-                {
-                    if (_fileSystem.WriteCacheBundleFile(_bundle, _tempFilePath))
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Succeed;
-                    }
-                    else
-                    {
-                        _steps = ESteps.Done;
-                        Status = EOperationStatus.Failed;
-                        Error = $"{_fileSystem.GetType().FullName} failed to write file !";
-                    }
-                }
-                else
-                {
-                    _steps = ESteps.Done;
-                    Status = EOperationStatus.Failed;
-                    Error = _verifyOperation.Error;
-                }
-
-                // 注意：验证完成后直接删除文件
-                if (File.Exists(_tempFilePath))
-                    File.Delete(_tempFilePath);
-            }
-        }
-        internal override void InternalWaitForAsyncComplete()
-        {
-            if (_steps != ESteps.Done)
-            {
-                YooLogger.Error($"Try load bundle {_bundle.BundleName} from remote : {_requestURL} !");
-            }
-        }
-
-        private void ClearTempFileWhenError()
-        {
-            if (_fileSystem.ResumeDownloadResponseCodes == null)
-                return;
-
-            //说明：如果遇到以下错误返回码，验证失败直接删除文件
-            if (_fileSystem.ResumeDownloadResponseCodes.Contains(HttpCode))
-            {
-                if (File.Exists(_tempFilePath))
-                    File.Delete(_tempFilePath);
-            }
-        }
-        private void CreateWebRequest(long fileBeginLength)
-        {
-            var handler = new DownloadHandlerFile(_tempFilePath, true);
-            handler.removeFileOnAbort = false;
-            _webRequest = DownloadSystemHelper.NewUnityWebRequestGet(_requestURL);
-            _webRequest.downloadHandler = handler;
-            _webRequest.disposeDownloadHandlerOnDispose = true;
-            if (fileBeginLength > 0)
-                _webRequest.SetRequestHeader("Range", $"bytes={fileBeginLength}-");
-            _webRequest.SendWebRequest();
-        }
-    }
-}

Assets/YooAsset/Runtime/FileSystem/DefaultCacheFileSystem/Operation/internal/UnityDownloadResumeFileOperation.cs.meta

@@ -1,11 +0,0 @@
-fileFormatVersion: 2
-guid: 9bfb785912326f942a31dc77762eb16a
-MonoImporter:
-  externalObjects: {}
-  serializedVersion: 2
-  defaultReferences: []
-  executionOrder: 0
-  icon: {instanceID: 0}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/DefaultEditorFileSystem.cs

@@ -11,6 +11,11 @@ namespace YooAsset
         protected readonly Dictionary<string, string> _records = new Dictionary<string, string>(10000);
         protected string _packageRoot;
 
+        /// <summary>
+        /// 下载后台接口
+        /// </summary>
+        public IDownloadBackend DownloadBackend { private set; get; }
+
         /// <summary>
         /// 包裹名称
         /// </summary>
@@ -142,9 +147,13 @@ namespace YooAsset
             PackageName = packageName;
 
             if (string.IsNullOrEmpty(packageRoot))
-                throw new Exception($"{nameof(DefaultEditorFileSystem)} root directory is null or empty !");
+                throw new YooFileSystemException($"{nameof(DefaultEditorFileSystem)} package root is null or empty !");
 
             _packageRoot = packageRoot;
+
+            // 创建默认的下载后台接口
+            if (DownloadBackend == null)
+                DownloadBackend = new UnityWebRequestBackend(DownloadSystemHelper.UnityWebRequestCreater);
         }
         public virtual void OnDestroy()
         {

Assets/YooAsset/Runtime/FileSystem/DefaultEditorFileSystem/Operation/internal/DownloadVirutalBundleOperation.cs

@@ -17,10 +17,10 @@ namespace YooAsset
         // 下载参数
         protected readonly DefaultEditorFileSystem _fileSystem;
         protected readonly DownloadFileOptions _options;
-        protected UnityVirtualBundleRequestOperation _unityDownloadFileOp;
+        protected IDownloadFileRequest _downloadFileOp;
 
         protected int _requestCount = 0;
-        protected float _tryAgainTimer;
+        protected float _tryAgainTimer = 0;
         protected int _failedTryAgain;
         private ESteps _steps = ESteps.None;
 
@@ -68,29 +68,22 @@ namespace YooAsset
 
                 string url = GetRequestURL();
                 int speed = _fileSystem.VirtualDownloadSpeed;
-                _unityDownloadFileOp = new UnityVirtualBundleRequestOperation(Bundle, speed, url);
-                _unityDownloadFileOp.StartOperation();
+                var args = new DownloadSimulateRequestArgs(url, Bundle.FileSize, speed);
+                _downloadFileOp = _fileSystem.DownloadBackend.CreateSimulateRequest(args);
+                _downloadFileOp.SendRequest();
                 _steps = ESteps.CheckRequest;
             }
 
             // 检测下载结果
             if (_steps == ESteps.CheckRequest)
             {
-                if (IsWaitForAsyncComplete)
-                    _unityDownloadFileOp.WaitForAsyncComplete();
-
-                // 因为并发数量限制，下载器可能被挂起！
-                if (_unityDownloadFileOp.Status == EOperationStatus.None)
+                Progress = _downloadFileOp.DownloadProgress;
+                DownloadedBytes = _downloadFileOp.DownloadedBytes;
+                DownloadProgress = _downloadFileOp.DownloadProgress;
+                if (_downloadFileOp.IsDone == false)
                     return;
 
-                _unityDownloadFileOp.UpdateOperation();
-                Progress = _unityDownloadFileOp.Progress;
-                DownloadedBytes = _unityDownloadFileOp.DownloadedBytes;
-                DownloadProgress = _unityDownloadFileOp.DownloadProgress;
-                if (_unityDownloadFileOp.IsDone == false)
-                    return;
-
-                if (_unityDownloadFileOp.Status == EOperationStatus.Succeed)
+                if (_downloadFileOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _fileSystem.RecordDownloadFile(Bundle);
                     _steps = ESteps.Done;
@@ -101,13 +94,13 @@ namespace YooAsset
                     if (IsWaitForAsyncComplete == false && _failedTryAgain > 0)
                     {
                         _steps = ESteps.TryAgain;
-                        YooLogger.Warning($"Failed download : {_unityDownloadFileOp.URL} Try again !");
+                        YooLogger.Warning($"Failed download : {_downloadFileOp.URL} Try again !");
                     }
                     else
                     {
                         _steps = ESteps.Done;
                         Status = EOperationStatus.Failed;
-                        Error = _unityDownloadFileOp.Error;
+                        Error = _downloadFileOp.Error;
                         YooLogger.Error(Error);
                     }
                 }
@@ -130,13 +123,11 @@ namespace YooAsset
         }
         internal override void InternalWaitForAsyncComplete()
         {
-            while (true)
+            if (_steps != ESteps.Done)
             {
-                if (ExecuteWhileDone())
-                {
-                    _steps = ESteps.Done;
-                    break;
-                }
+                _steps = ESteps.Done;
+                Status = EOperationStatus.Failed;
+                Error = $"Try load bundle {Bundle.BundleName} from remote !";
             }
         }
 

Assets/YooAsset/Runtime/FileSystem/DefaultWebRemoteFileSystem/DefaultWebRemoteFileSystem.cs

@@ -10,6 +10,11 @@ namespace YooAsset
     /// </summary>
     internal class DefaultWebRemoteFileSystem : IFileSystem
     {
+        /// <summary>
+        /// 下载后台接口
+        /// </summary>
+        public IDownloadBackend DownloadBackend { private set; get; }
+
         /// <summary>
         /// 包裹名称
         /// </summary>
@@ -128,6 +133,10 @@ namespace YooAsset
         public virtual void OnCreate(string packageName, string packageRoot)
         {
             PackageName = packageName;
+
+            // 创建默认的下载后台接口
+            if (DownloadBackend == null)
+                DownloadBackend = new UnityWebRequestBackend(DownloadSystemHelper.UnityWebRequestCreater);
         }
         public virtual void OnDestroy()
         {

Assets/YooAsset/Runtime/FileSystem/DefaultWebRemoteFileSystem/Operation/DWRFSLoadBundleOperation.cs

@@ -38,16 +38,16 @@ namespace YooAsset
                     string fallbackURL = _fileSystem.RemoteServices.GetRemoteFallbackURL(_bundle.FileName);
                     DownloadFileOptions options = new DownloadFileOptions(int.MaxValue);
                     options.SetURL(mainURL, fallbackURL);
-                    
+
                     if (_bundle.Encrypted)
                     {
-                        _loadWebAssetBundleOp = new LoadWebEncryptAssetBundleOperation(_bundle, options, _fileSystem.DecryptionServices);
+                        _loadWebAssetBundleOp = new LoadWebEncryptAssetBundleOperation(_bundle, options, _fileSystem.DecryptionServices, _fileSystem.DownloadBackend);
                         _loadWebAssetBundleOp.StartOperation();
                         AddChildOperation(_loadWebAssetBundleOp);
                     }
                     else
                     {
-                        _loadWebAssetBundleOp = new LoadWebNormalAssetBundleOperation(_bundle, options, _fileSystem.DisableUnityWebCache);
+                        _loadWebAssetBundleOp = new LoadWebNormalAssetBundleOperation(_bundle, options, _fileSystem.DisableUnityWebCache, _fileSystem.DownloadBackend);
                         _loadWebAssetBundleOp.StartOperation();
                         AddChildOperation(_loadWebAssetBundleOp);
                     }

Assets/YooAsset/Runtime/FileSystem/DefaultWebRemoteFileSystem/Operation/DWRFSLoadPackageManifestOperation.cs

@@ -38,7 +38,7 @@ namespace YooAsset
             {
                 if (_requestWebPackageHashOp == null)
                 {
-                    _requestWebPackageHashOp = new RequestWebPackageHashOperation(_fileSystem.RemoteServices, _fileSystem.PackageName, _packageVersion, _timeout);
+                    _requestWebPackageHashOp = new RequestWebPackageHashOperation(_fileSystem.RemoteServices, _fileSystem.DownloadBackend, _fileSystem.PackageName, _packageVersion, _timeout);
                     _requestWebPackageHashOp.StartOperation();
                     AddChildOperation(_requestWebPackageHashOp);
                 }
@@ -67,7 +67,8 @@ namespace YooAsset
                     string packageName = _fileSystem.PackageName;
                     var manifestServices = _fileSystem.ManifestServices;
                     var remoteServices = _fileSystem.RemoteServices;
-                    _loadWebPackageManifestOp = new LoadWebPackageManifestOperation(manifestServices, remoteServices, packageName, _packageVersion, packageHash, _timeout);
+                    var downloadBackend = _fileSystem.DownloadBackend;
+                    _loadWebPackageManifestOp = new LoadWebPackageManifestOperation(manifestServices, remoteServices, downloadBackend, packageName, _packageVersion, packageHash, _timeout);
                     _loadWebPackageManifestOp.StartOperation();
                     AddChildOperation(_loadWebPackageManifestOp);
                 }

Assets/YooAsset/Runtime/FileSystem/DefaultWebRemoteFileSystem/Operation/DWRFSRequestPackageVersionOperation.cs

@@ -36,7 +36,7 @@ namespace YooAsset
             {
                 if (_requestWebPackageVersionOp == null)
                 {
-                    _requestWebPackageVersionOp = new RequestWebPackageVersionOperation(_fileSystem.RemoteServices, _fileSystem.PackageName, _appendTimeTicks, _timeout);
+                    _requestWebPackageVersionOp = new RequestWebPackageVersionOperation(_fileSystem.RemoteServices, _fileSystem.DownloadBackend, _fileSystem.PackageName, _appendTimeTicks, _timeout);
                     _requestWebPackageVersionOp.StartOperation();
                     AddChildOperation(_requestWebPackageVersionOp);
                 }

Assets/YooAsset/Runtime/FileSystem/DefaultWebServerFileSystem/DefaultWebServerFileSystem.cs

@@ -24,6 +24,11 @@ namespace YooAsset
         protected readonly Dictionary<string, string> _webFilePathMapping = new Dictionary<string, string>(10000);
         protected string _webPackageRoot = string.Empty;
 
+        /// <summary>
+        /// 下载后台接口
+        /// </summary>
+        public IDownloadBackend DownloadBackend { private set; get; }
+
         /// <summary>
         /// 包裹名称
         /// </summary>
@@ -138,6 +143,10 @@ namespace YooAsset
                 _webPackageRoot = GetDefaultWebPackageRoot(packageName);
             else
                 _webPackageRoot = packageRoot;
+
+            // 创建默认的下载后台接口
+            if (DownloadBackend == null)
+                DownloadBackend = new UnityWebRequestBackend(DownloadSystemHelper.UnityWebRequestCreater);
         }
         public virtual void OnDestroy()
         {

Assets/YooAsset/Runtime/FileSystem/DefaultWebServerFileSystem/Operation/DWSFSLoadBundleOperation.cs

@@ -41,13 +41,13 @@ namespace YooAsset
 
                     if (_bundle.Encrypted)
                     {
-                        _loadWebAssetBundleOp = new LoadWebEncryptAssetBundleOperation(_bundle, options, _fileSystem.DecryptionServices);
+                        _loadWebAssetBundleOp = new LoadWebEncryptAssetBundleOperation(_bundle, options, _fileSystem.DecryptionServices, _fileSystem.DownloadBackend);
                         _loadWebAssetBundleOp.StartOperation();
                         AddChildOperation(_loadWebAssetBundleOp);
                     }
                     else
                     {
-                        _loadWebAssetBundleOp = new LoadWebNormalAssetBundleOperation(_bundle, options, _fileSystem.DisableUnityWebCache);
+                        _loadWebAssetBundleOp = new LoadWebNormalAssetBundleOperation(_bundle, options, _fileSystem.DisableUnityWebCache, _fileSystem.DownloadBackend);
                         _loadWebAssetBundleOp.StartOperation();
                         AddChildOperation(_loadWebAssetBundleOp);
                     }

Assets/YooAsset/Runtime/FileSystem/DefaultWebServerFileSystem/Operation/internal/LoadWebServerCatalogFileOperation.cs

@@ -14,7 +14,7 @@ namespace YooAsset
 
         private readonly DefaultWebServerFileSystem _fileSystem;
         private readonly int _timeout;
-        private UnityWebDataRequestOperation _webDataRequestOp;
+        private IDownloadBytesRequest _webDataRequestOp;
         private ESteps _steps = ESteps.None;
 
         internal LoadWebServerCatalogFileOperation(DefaultWebServerFileSystem fileSystem, int timeout)
@@ -37,16 +37,15 @@ namespace YooAsset
                 {
                     string filePath = _fileSystem.GetCatalogBinaryFileLoadPath();
                     string url = DownloadSystemHelper.ConvertToWWWPath(filePath);
-                    _webDataRequestOp = new UnityWebDataRequestOperation(url, _timeout);
-                    _webDataRequestOp.StartOperation();
-                    AddChildOperation(_webDataRequestOp);
+                    var args = new DownloadDataRequestArgs(url, _timeout, 0);
+                    _webDataRequestOp = _fileSystem.DownloadBackend.CreateBytesRequest(args);
+                    _webDataRequestOp.SendRequest();
                 }
 
-                _webDataRequestOp.UpdateOperation();
                 if (_webDataRequestOp.IsDone == false)
                     return;
 
-                if (_webDataRequestOp.Status == EOperationStatus.Succeed)
+                if (_webDataRequestOp.Status == EDownloadRequestStatus.Succeed)
                 {
                     _steps = ESteps.LoadCatalog;
                 }
@@ -81,11 +80,11 @@ namespace YooAsset
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Succeed;
                 }
-                catch (Exception e)
+                catch (Exception ex)
                 {
                     _steps = ESteps.Done;
                     Status = EOperationStatus.Failed;
-                    Error = $"Failed to load catalog file : {e.Message}";
+                    Error = $"Failed to load catalog file : {ex.Message}";
                 }
             }
         }