update download system

support to cancel download operation

Assets/YooAsset/Runtime/DownloadSystem/DownloadManager.cs

@@ -49,7 +49,9 @@ namespace YooAsset
 				var downloader = valuePair.Value;
 				downloader.Update();
 				if (downloader.IsDone())
+				{
 					_removeList.Add(valuePair.Key);
+				}
 			}
 
 			// 移除下载器
@@ -82,7 +84,10 @@ namespace YooAsset
 		{
 			// 查询存在的下载器
 			if (_downloaders.TryGetValue(bundleInfo.CachedDataFilePath, out var downloader))
+			{
+				downloader.Reference();
 				return downloader;
+			}
 
 			// 如果资源已经缓存
 			if (bundleInfo.IsCached())
@@ -92,22 +97,19 @@ namespace YooAsset
 			}
 
 			// 创建新的下载器	
+			DownloaderBase newDownloader = null;
 			YooLogger.Log($"Beginning to download bundle : {bundleInfo.Bundle.BundleName} URL : {bundleInfo.RemoteMainURL}");
 #if UNITY_WEBGL
 			if (bundleInfo.Bundle.Buildpipeline == DefaultBuildPipeline.RawFileBuildPipelineName)
 			{
 				FileUtility.CreateFileDirectory(bundleInfo.CachedDataFilePath);
 				System.Type requesterType = typeof(FileGeneralRequest);
-				DownloaderBase newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
-				_downloaders.Add(bundleInfo.CachedDataFilePath, newDownloader);
-				return newDownloader;
+				newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
 			}
 			else
 			{
 				System.Type requesterType = typeof(AssetBundleWebRequest);
-				WebDownloader newDownloader = new WebDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
-				_downloaders.Add(bundleInfo.CachedDataFilePath, newDownloader);
-				return newDownloader;
+				newDownloader = new WebDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
 			}
 #else
 			FileUtility.CreateFileDirectory(bundleInfo.CachedDataFilePath);
@@ -115,18 +117,34 @@ namespace YooAsset
 			if (resumeDownload)
 			{
 				System.Type requesterType = typeof(FileResumeRequest);
-				DownloaderBase newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
-				_downloaders.Add(bundleInfo.CachedDataFilePath, newDownloader);
-				return newDownloader;
+				newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
 			}
 			else
 			{
 				System.Type requesterType = typeof(FileGeneralRequest);
-				DownloaderBase newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
-				_downloaders.Add(bundleInfo.CachedDataFilePath, newDownloader);
-				return newDownloader;
+				newDownloader = new FileDownloader(bundleInfo, requesterType, failedTryAgain, timeout);
 			}
 #endif
+
+			// 返回新创建的下载器
+			_downloaders.Add(bundleInfo.CachedDataFilePath, newDownloader);
+			newDownloader.Reference();
+			return newDownloader;
+		}
+
+		/// <summary>
+		/// 停止不再使用的下载器
+		/// </summary>
+		public void AbortUnusedDownloader()
+		{
+			foreach (var valuePair in _downloaders)
+			{
+				var downloader = valuePair.Value;
+				if (downloader.RefCount <= 0)
+				{
+					downloader.Abort();
+				}
+			}
 		}
 	}
 }

Assets/YooAsset/Runtime/DownloadSystem/Downloader/DownloaderBase.cs

@@ -49,6 +49,11 @@ namespace YooAsset
 		/// </summary>
 		public ulong DownloadedBytes { protected set; get; }
 
+		/// <summary>
+		/// 引用计数
+		/// </summary>
+		public int RefCount { private set; get; }
+
 
 		public DownloaderBase(BundleInfo bundleInfo, System.Type requesterType, int failedTryAgain, int timeout)
 		{
@@ -63,20 +68,19 @@ namespace YooAsset
 		public abstract AssetBundle GetAssetBundle();
 
 		/// <summary>
-		/// 获取下载文件的大小
+		/// 引用（引用计数递加）
 		/// </summary>
-		/// <returns></returns>
-		public long GetDownloadFileSize()
+		public void Reference()
 		{
-			return _bundleInfo.Bundle.FileSize;
+			RefCount++;
 		}
 
 		/// <summary>
-		/// 获取下载文件的资源包名
+		/// 释放（引用计数递减）
 		/// </summary>
-		public string GetDownloadBundleName()
+		public void Release()
 		{
-			return _bundleInfo.Bundle.BundleName;
+			RefCount--;
 		}
 
 		/// <summary>
@@ -119,6 +123,23 @@ namespace YooAsset
 			return $"Failed to download : {_requestURL} Error : {_lastestNetError} Code : {_lastestHttpCode}";
 		}
 
+		/// <summary>
+		/// 获取下载文件的大小
+		/// </summary>
+		/// <returns></returns>
+		public long GetDownloadFileSize()
+		{
+			return _bundleInfo.Bundle.FileSize;
+		}
+
+		/// <summary>
+		/// 获取下载的资源包名称
+		/// </summary>
+		public string GetDownloadBundleName()
+		{
+			return _bundleInfo.Bundle.BundleName;
+		}
+
 
 		/// <summary>
 		/// 获取网络请求地址