添加失败文件重试机制

Form1.cs

@@ -257,6 +257,7 @@ namespace CheckDownload
                 _downloadedFiles.Clear();
 
                 var options = new ParallelOptions { MaxDegreeOfParallelism = 4 };
+                var failedFiles = new Dictionary<string, string>(); // 记录下载失败的文件
 
                 await Task.Run(() =>
                 {
@@ -316,15 +317,32 @@ namespace CheckDownload
                             else
                             {
                                 UpdateStatus($"备用方案已执行");
+                                // 记录失败的文件，稍后重试
+                                lock (failedFiles)
+                                {
+                                    failedFiles[filePath] = expectedMd5;
+                                }
                             }
                         }
                         catch (Exception ex)
                         {
                             UpdateStatus($"下载文件 {filePath} 失败: {ex.Message}");
+                            // 记录失败的文件，稍后重试
+                            lock (failedFiles)
+                            {
+                                failedFiles[filePath] = expectedMd5;
+                            }
                         }
                     });
                 });
 
+                // 如果有失败的文件，进行重试
+                if (failedFiles.Count > 0)
+                {
+                    UpdateStatus($"开始重试 {failedFiles.Count} 个失败的文件...");
+                    await RetryFailedFiles(failedFiles);
+                }
+
                 if (_downloadedFiles.Count != fileList.Count)
                 {
                     throw new Exception($"部分文件下载失败，成功 {_downloadedFiles.Count}/{fileList.Count}");
@@ -339,6 +357,105 @@ namespace CheckDownload
             }
         }
 
+        /// <summary>
+        /// 重试下载失败的文件
+        /// </summary>
+        /// <param name="failedFiles">失败的文件字典</param>
+        private async Task RetryFailedFiles(Dictionary<string, string> failedFiles)
+        {
+            const int maxRetries = 2; // 最大重试次数
+            var retryFiles = new Dictionary<string, string>(failedFiles);
+
+            for (int retryCount = 1; retryCount <= maxRetries; retryCount++)
+            {
+                if (retryFiles.Count == 0) break;
+
+                UpdateStatus($"第 {retryCount} 次重试，剩余 {retryFiles.Count} 个文件...");
+                var currentRetryFiles = new Dictionary<string, string>(retryFiles);
+                retryFiles.Clear();
+
+                foreach (var file in currentRetryFiles)
+                {
+                    string filePath = file.Key;
+                    string expectedMd5 = file.Value;
+
+                    try
+                    {
+                        UpdateStatus($"重试下载: {filePath}");
+                        
+                        // 先尝试主下载
+                        bool success = false;
+                        try
+                        {
+                            OssClient client = new OssClient(OssEndpoint, OssAccessKeyId, OssAccessKeySecret);
+                            string ossKey = $"File/{expectedMd5}";
+                            var obj = client.GetObject(OssBucketName, ossKey);
+                            
+                            string tempFilePath = Path.Combine(_tempDirectory, filePath);
+                            string tempDir = Path.GetDirectoryName(tempFilePath);
+                            if (!Directory.Exists(tempDir))
+                            {
+                                Directory.CreateDirectory(tempDir);
+                            }
+
+                            using (var fileStream = File.Create(tempFilePath))
+                            {
+                                obj.Content.CopyTo(fileStream);
+                            }
+                            success = true;
+                        }
+                        catch (Exception ex) when (ex is OssException || ex is WebException)
+                        {
+                            // 主下载失败，尝试备用方案
+                            string ossKey = $"File/{expectedMd5}";
+                            string tempFilePath = Path.Combine(_tempDirectory, filePath);
+                            success = DownloadWithFallback(ossKey, tempFilePath);
+                        }
+
+                        if (success)
+                        {
+                            lock (_downloadedFiles)
+                            {
+                                _downloadedFiles[filePath] = (null, expectedMd5);
+                            }
+                            Interlocked.Increment(ref _completedCount);
+                            int progress = (int)((double)_completedCount / _totalCount * 95);
+                            UpdateProgressValue(progress);
+                            UpdateStatus($"重试成功: {filePath}");
+                        }
+                        else
+                        {
+                            retryFiles[filePath] = expectedMd5;
+                            UpdateStatus($"重试失败: {filePath}");
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        retryFiles[filePath] = expectedMd5;
+                        UpdateStatus($"重试异常: {filePath} - {ex.Message}");
+                    }
+
+                    // 重试间隔，避免过于频繁
+                    await Task.Delay(1000);
+                }
+
+                if (retryFiles.Count > 0 && retryCount < maxRetries)
+                {
+                    UpdateStatus($"等待 3 秒后进行第 {retryCount + 1} 次重试...");
+                    await Task.Delay(3000);
+                }
+            }
+
+            if (retryFiles.Count > 0)
+            {
+                UpdateStatus($"重试完成，仍有 {retryFiles.Count} 个文件下载失败");
+            }
+            else
+            {
+                UpdateStatus("所有文件重试成功！");
+            }
+        }
+
         private async Task<List<string>> GetIpAddressesForDomain(string domain)
         {
             try