404 lines
14 KiB
C#
404 lines
14 KiB
C#
using System.Net;
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using System.Text.Json;
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using WorkCameraExport.Services.Interfaces;
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namespace WorkCameraExport.Services
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{
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/// <summary>
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/// 可恢复下载器 - 支持断点续传
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/// </summary>
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public class ResumableDownloader : IDisposable
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{
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private readonly HttpClient _httpClient;
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private readonly ILogService? _logService;
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private readonly string _downloadStateDir;
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private bool _disposed;
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// 下载状态文件扩展名
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private const string StateFileExtension = ".download";
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// 临时文件扩展名
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private const string TempFileExtension = ".tmp";
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// 分块大小（1MB）
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private const int ChunkSize = 1024 * 1024;
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public ResumableDownloader(IConfigService configService, ILogService? logService = null)
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{
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_logService = logService;
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_downloadStateDir = Path.Combine(configService.TempPath, "downloads");
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if (!Directory.Exists(_downloadStateDir))
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{
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Directory.CreateDirectory(_downloadStateDir);
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}
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_httpClient = new HttpClient
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{
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Timeout = TimeSpan.FromMinutes(5)
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};
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_httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("WorkCameraExport/2.0 (Windows; .NET)");
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}
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/// <summary>
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/// 下载文件（支持断点续传）
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/// </summary>
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public async Task<bool> DownloadFileAsync(
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string url,
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string outputPath,
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IProgress<DownloadProgressInfo>? progress = null,
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CancellationToken cancellationToken = default)
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{
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var downloadId = GetDownloadId(url);
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var stateFilePath = Path.Combine(_downloadStateDir, $"{downloadId}{StateFileExtension}");
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var tempFilePath = outputPath + TempFileExtension;
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try
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{
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// 加载或创建下载状态
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var state = LoadDownloadState(stateFilePath) ?? new DownloadState
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{
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Url = url,
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OutputPath = outputPath,
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DownloadedBytes = 0,
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TotalBytes = 0,
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StartTime = DateTime.Now
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};
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// 检查临时文件是否存在，获取已下载的字节数
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long downloadedBytes = 0;
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if (File.Exists(tempFilePath))
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{
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var fileInfo = new FileInfo(tempFilePath);
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downloadedBytes = fileInfo.Length;
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state.DownloadedBytes = downloadedBytes;
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}
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// 获取文件总大小
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var totalBytes = await GetFileSizeAsync(url, cancellationToken);
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if (totalBytes <= 0)
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{
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_logService?.Warn($"无法获取文件大小: {url}");
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// 如果无法获取文件大小，尝试普通下载
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return await DownloadWithoutResumeAsync(url, outputPath, progress, cancellationToken);
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}
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state.TotalBytes = totalBytes;
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// 如果已经下载完成
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if (downloadedBytes >= totalBytes)
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{
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if (File.Exists(tempFilePath))
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{
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File.Move(tempFilePath, outputPath, true);
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}
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CleanupDownloadState(stateFilePath);
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progress?.Report(new DownloadProgressInfo(totalBytes, totalBytes, true));
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return true;
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}
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// 创建带 Range 头的请求
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using var request = new HttpRequestMessage(HttpMethod.Get, url);
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if (downloadedBytes > 0)
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{
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request.Headers.Range = new System.Net.Http.Headers.RangeHeaderValue(downloadedBytes, null);
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_logService?.Info($"断点续传: 从 {downloadedBytes} 字节开始下载");
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}
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using var response = await _httpClient.SendAsync(
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request,
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HttpCompletionOption.ResponseHeadersRead,
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cancellationToken);
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// 检查服务器是否支持断点续传
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if (response.StatusCode == HttpStatusCode.PartialContent ||
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response.StatusCode == HttpStatusCode.OK)
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{
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// 如果服务器返回 200 OK（不支持 Range），需要重新下载
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if (response.StatusCode == HttpStatusCode.OK && downloadedBytes > 0)
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{
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_logService?.Info("服务器不支持断点续传，重新下载");
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downloadedBytes = 0;
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if (File.Exists(tempFilePath))
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{
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File.Delete(tempFilePath);
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}
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}
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// 打开文件流（追加模式）
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using var fileStream = new FileStream(
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tempFilePath,
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downloadedBytes > 0 ? FileMode.Append : FileMode.Create,
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FileAccess.Write,
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FileShare.None,
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bufferSize: ChunkSize,
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useAsync: true);
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using var contentStream = await response.Content.ReadAsStreamAsync(cancellationToken);
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var buffer = new byte[ChunkSize];
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int bytesRead;
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var lastProgressReport = DateTime.Now;
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while ((bytesRead = await contentStream.ReadAsync(buffer, cancellationToken)) > 0)
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{
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await fileStream.WriteAsync(buffer.AsMemory(0, bytesRead), cancellationToken);
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downloadedBytes += bytesRead;
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state.DownloadedBytes = downloadedBytes;
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// 每秒报告一次进度
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if ((DateTime.Now - lastProgressReport).TotalMilliseconds >= 500)
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{
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progress?.Report(new DownloadProgressInfo(downloadedBytes, totalBytes, false));
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SaveDownloadState(stateFilePath, state);
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lastProgressReport = DateTime.Now;
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}
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}
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// 下载完成，移动临时文件到目标位置
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fileStream.Close();
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File.Move(tempFilePath, outputPath, true);
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CleanupDownloadState(stateFilePath);
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progress?.Report(new DownloadProgressInfo(totalBytes, totalBytes, true));
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_logService?.Info($"下载完成: {url}");
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return true;
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}
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else
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{
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_logService?.Warn($"下载失败，状态码: {response.StatusCode}");
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return false;
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}
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}
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catch (OperationCanceledException)
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{
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_logService?.Info($"下载已取消: {url}");
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return false;
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}
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catch (Exception ex)
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{
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_logService?.Error($"下载异常: {url}", ex);
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return false;
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}
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}
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/// <summary>
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/// 不支持断点续传的普通下载
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/// </summary>
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private async Task<bool> DownloadWithoutResumeAsync(
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string url,
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string outputPath,
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IProgress<DownloadProgressInfo>? progress,
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CancellationToken cancellationToken)
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{
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try
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{
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using var response = await _httpClient.GetAsync(url, cancellationToken);
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if (response.IsSuccessStatusCode)
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{
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var data = await response.Content.ReadAsByteArrayAsync(cancellationToken);
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await File.WriteAllBytesAsync(outputPath, data, cancellationToken);
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progress?.Report(new DownloadProgressInfo(data.Length, data.Length, true));
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return true;
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}
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return false;
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}
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catch (Exception ex)
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{
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_logService?.Error($"普通下载失败: {url}", ex);
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return false;
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}
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}
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/// <summary>
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/// 获取文件大小
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/// </summary>
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private async Task<long> GetFileSizeAsync(string url, CancellationToken cancellationToken)
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{
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try
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{
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using var request = new HttpRequestMessage(HttpMethod.Head, url);
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using var response = await _httpClient.SendAsync(request, cancellationToken);
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if (response.IsSuccessStatusCode && response.Content.Headers.ContentLength.HasValue)
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{
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return response.Content.Headers.ContentLength.Value;
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}
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}
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catch (Exception ex)
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{
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_logService?.Warn($"获取文件大小失败: {ex.Message}");
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}
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return -1;
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}
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/// <summary>
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/// 获取下载 ID（基于 URL 的哈希）
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/// </summary>
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private static string GetDownloadId(string url)
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{
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using var sha256 = System.Security.Cryptography.SHA256.Create();
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var hashBytes = sha256.ComputeHash(System.Text.Encoding.UTF8.GetBytes(url));
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return Convert.ToHexString(hashBytes)[..16];
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}
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/// <summary>
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/// 加载下载状态
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/// </summary>
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private DownloadState? LoadDownloadState(string stateFilePath)
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{
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try
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{
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if (File.Exists(stateFilePath))
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{
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var json = File.ReadAllText(stateFilePath);
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return JsonSerializer.Deserialize<DownloadState>(json);
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}
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}
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catch (Exception ex)
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{
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_logService?.Warn($"加载下载状态失败: {ex.Message}");
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}
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return null;
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}
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/// <summary>
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/// 保存下载状态
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/// </summary>
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private void SaveDownloadState(string stateFilePath, DownloadState state)
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{
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try
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{
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var json = JsonSerializer.Serialize(state);
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File.WriteAllText(stateFilePath, json);
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}
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catch (Exception ex)
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{
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_logService?.Warn($"保存下载状态失败: {ex.Message}");
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}
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}
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/// <summary>
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/// 清理下载状态
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/// </summary>
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private void CleanupDownloadState(string stateFilePath)
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{
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try
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{
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if (File.Exists(stateFilePath))
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{
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File.Delete(stateFilePath);
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}
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}
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catch
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{
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// 忽略清理错误
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}
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}
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/// <summary>
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/// 清理所有未完成的下载
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/// </summary>
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public void CleanupIncompleteDownloads()
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{
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try
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{
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if (Directory.Exists(_downloadStateDir))
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{
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foreach (var file in Directory.GetFiles(_downloadStateDir, $"*{StateFileExtension}"))
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{
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try { File.Delete(file); } catch { }
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}
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}
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}
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catch (Exception ex)
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{
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_logService?.Warn($"清理未完成下载失败: {ex.Message}");
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}
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}
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/// <summary>
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/// 获取未完成的下载列表
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/// </summary>
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public List<DownloadState> GetIncompleteDownloads()
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{
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var result = new List<DownloadState>();
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try
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{
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if (Directory.Exists(_downloadStateDir))
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{
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foreach (var file in Directory.GetFiles(_downloadStateDir, $"*{StateFileExtension}"))
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{
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var state = LoadDownloadState(file);
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if (state != null)
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{
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result.Add(state);
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}
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}
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}
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}
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catch (Exception ex)
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{
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_logService?.Warn($"获取未完成下载列表失败: {ex.Message}");
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}
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return result;
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}
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#region IDisposable
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public void Dispose()
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{
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Dispose(true);
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GC.SuppressFinalize(this);
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}
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protected virtual void Dispose(bool disposing)
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{
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if (!_disposed)
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{
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if (disposing)
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{
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_httpClient.Dispose();
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}
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_disposed = true;
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}
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}
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#endregion
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}
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/// <summary>
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/// 下载状态
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/// </summary>
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public class DownloadState
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{
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public string Url { get; set; } = "";
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public string OutputPath { get; set; } = "";
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public long DownloadedBytes { get; set; }
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public long TotalBytes { get; set; }
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public DateTime StartTime { get; set; }
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}
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/// <summary>
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/// 下载进度信息
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/// </summary>
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public class DownloadProgressInfo
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{
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public long DownloadedBytes { get; }
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public long TotalBytes { get; }
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public bool IsCompleted { get; }
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public double ProgressPercent => TotalBytes > 0 ? (double)DownloadedBytes / TotalBytes * 100 : 0;
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public DownloadProgressInfo(long downloadedBytes, long totalBytes, bool isCompleted)
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{
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DownloadedBytes = downloadedBytes;
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TotalBytes = totalBytes;
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IsCompleted = isCompleted;
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}
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}
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}
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