Question

假设我有一个文件列表，我必须使用c＃project中的ftp相关类复制到Web服务器。在这里我想使用Async / Await功能，并且还希望同时显示多个文件上传的多个进度条。每个进度条指示每个文件上载状态。所以指导我如何做到这一点。

当我们与后台工作人员合作完成这类工作时，这很容易，因为后台工作人员有进度变更事件。那么如何使用Async / Await处理这种情况。如果可能的话，用示例代码指导我。感谢

Answer 1

的进展示例代码

public async Task<int> UploadPicturesAsync(List<Image> imageList, 
     IProgress<int> progress)
{
      int totalCount = imageList.Count;
      int processCount = await Task.Run<int>(() =>
      {
          int tempCount = 0;
          foreach (var image in imageList)
          {
              //await the processing and uploading logic here
              int processed = await UploadAndProcessAsync(image);
              if (progress != null)
              {
                  progress.Report((tempCount * 100 / totalCount));
              }
              tempCount++;
          }
          return tempCount;
      });
      return processCount;
}

private async void Start_Button_Click(object sender, RoutedEventArgs e)
{
    int uploads=await UploadPicturesAsync(GenerateTestImages(),
        new Progress<int>(percent => progressBar1.Value = percent));
}

如果您想独立报告每个文件，您将拥有IProgress的不同基本类型：

public async Task<int> UploadPicturesAsync(List<Image> imageList, 
     IProgress<int[]> progress)
{
      int totalCount = imageList.Count;
      var progressCount = Enumerable.Repeat(0, totalCount).ToArray(); 
      return Task.WhenAll( imageList.map( (image, index) =>                   
        UploadAndProcessAsync(image, (percent) => { 
          progressCount[index] = percent;
          progress?.Report(progressCount);  
        });              
      ));
}

private async void Start_Button_Click(object sender, RoutedEventArgs e)
{
    int uploads=await UploadPicturesAsync(GenerateTestImages(),
        new Progress<int[]>(percents => ... do something ...));
}

如何使用Async / Await进行进度报告

1 个答案: