fix #562

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

@@ -559,6 +559,21 @@ namespace YooAsset
             };
             return DecryptionServices.LoadAssetBundleAsync(fileInfo);
         }
+
+        /// <summary>
+        /// 加载加密资源文件
+        /// </summary>
+        public DecryptResult LoadEncryptedAssetBundleFallback(PackageBundle bundle)
+        {
+            string filePath = GetCacheBundleFileLoadPath(bundle);
+            var fileInfo = new DecryptFileInfo()
+            {
+                BundleName = bundle.BundleName,
+                FileLoadCRC = bundle.UnityCRC,
+                FileLoadPath = filePath,
+            };
+            return DecryptionServices.LoadAssetBundleFallback(fileInfo);
+        }
         #endregion
     }
 }

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

@@ -163,6 +163,17 @@ namespace YooAsset
                 if (verifyResult == EFileVerifyResult.Succeed)
                 {
                     if (_bundle.Encrypted)
+                    {
+                        var decryptResult = _fileSystem.LoadEncryptedAssetBundleFallback(_bundle);
+                        _assetBundle = decryptResult.Result;
+                        if (_assetBundle != null)
+                        {
+                            _steps = ESteps.Done;
+                            Result = new AssetBundleResult(_fileSystem, _bundle, _assetBundle, _managedStream);
+                            Status = EOperationStatus.Succeed;
+                            return;
+                        }
+                        else
                         {
                             _steps = ESteps.Done;
                             Status = EOperationStatus.Failed;
@@ -170,6 +181,7 @@ namespace YooAsset
                             YooLogger.Error(Error);
                             return;
                         }
+                    }
 
                     // 注意：在安卓移动平台，华为和三星真机上有极小概率加载资源包失败。
                     // 说明：大多数情况在首次安装下载资源到沙盒内，游戏过程中切换到后台再回到游戏内有很大概率触发！

Assets/YooAsset/Runtime/Services/IDecryptionServices.cs

@@ -51,6 +51,14 @@ namespace YooAsset
         /// </summary>
         DecryptResult LoadAssetBundleAsync(DecryptFileInfo fileInfo);
 
+        /// <summary>
+        /// 后备方式获取解密的资源包对象
+        /// 注意：当正常解密方法失败后，会触发后备加载！
+        /// 说明：建议通过LoadFromMemory()方法加载资源对象作为保底机制。
+        /// issues : https://github.com/tuyoogame/YooAsset/issues/562
+        /// </summary>
+        DecryptResult LoadAssetBundleFallback(DecryptFileInfo fileInfo);
+        
         /// <summary>
         /// 获取解密的字节数据
         /// </summary>

Assets/YooAsset/Samples~/Test Sample/Runtime/T2_TestBuldinFileSystem/TestBundleEncryption.cs

@@ -147,6 +147,14 @@ public class FileStreamTestDecryption : IDecryptionServices
         return decryptResult;
     }
 
+    /// <summary>
+    /// 后备方式获取解密的资源包对象
+    /// </summary>
+    DecryptResult IDecryptionServices.LoadAssetBundleFallback(DecryptFileInfo fileInfo)
+    {
+        return new DecryptResult();
+    }
+
     /// <summary>
     /// 获取解密的字节数据
     /// </summary>
@@ -198,6 +206,14 @@ public class FileOffsetTestDecryption : IDecryptionServices
         return decryptResult;
     }
 
+    /// <summary>
+    /// 后备方式获取解密的资源包对象
+    /// </summary>
+    DecryptResult IDecryptionServices.LoadAssetBundleFallback(DecryptFileInfo fileInfo)
+    {
+        return new DecryptResult();
+    }
+
     /// <summary>
     /// 获取解密的字节数据
     /// </summary>