如何实现Portable HttpClient的进度报告

2 回答

• 1

  我编写了以下代码来实现进度报告 . 代码支持我想要的所有平台;但是，您需要引用以下NuGet包：

  • Microsoft.Net.Http

  • Microsoft.Bcl.Async

  这是代码：

  public async Task DownloadFileAsync(string url, IProgress<double> progress, CancellationToken token)
  {
      var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, token);
  
      if (!response.IsSuccessStatusCode)
      {
          throw new Exception(string.Format("The request returned with HTTP status code {0}", response.StatusCode));
      }
  
      var total = response.Content.Headers.ContentLength.HasValue ? response.Content.Headers.ContentLength.Value : -1L;
      var canReportProgress = total != -1 && progress != null;
  
      using (var stream = await response.Content.ReadAsStreamAsync())
      {
          var totalRead = 0L;
          var buffer = new byte[4096];
          var isMoreToRead = true;
  
          do
          {
              token.ThrowIfCancellationRequested();
  
              var read = await stream.ReadAsync(buffer, 0, buffer.Length, token);
  
              if (read == 0)
              {
                  isMoreToRead = false;
              }
              else
              {
                  var data = new byte[read];
                  buffer.ToList().CopyTo(0, data, 0, read);
  
                  // TODO: put here the code to write the file to disk
  
                  totalRead += read;
  
                  if (canReportProgress)
                  {
                      progress.Report((totalRead * 1d) / (total * 1d) * 100);
                  }
              }
          } while (isMoreToRead);
      }
  }
  

  使用它很简单：

  var progress = new Microsoft.Progress<double>();
  progress.ProgressChanged += (sender, value) => System.Console.Write("\r%{0:N0}", value);
  
  var cancellationToken = new CancellationTokenSource();
  
  await DownloadFileAsync("http://www.dotpdn.com/files/Paint.NET.3.5.11.Install.zip", progress, cancellationToken.Token);
  

  回复于 2024-04-17T03:26:36+08:00
• 18

  您可以指定HttpCompletionOption.ResponseHeadersRead，然后在从流中读取时获取流并报告进度 . 见this similar question .

  回复于 2024-04-17T03:26:36+08:00