如何使用 Async/Await 进行进度报告 [英] How to do progress reporting using Async/Await

问题描述

假设我有一个文件列表，我必须使用 c# 项目中的 ftp 相关类将这些文件复制到 Web 服务器.在这里我想使用 Async/Await 功能，还想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传状态.所以请指导我如何做到这一点.

suppose i have a list of files which i have to copy to web server using ftp related classes in c# project. here i want to use Async/Await feature and also want to show multiple progress bar for multiple file uploading at same time. each progress bar indicate each file upload status. so guide me how can i do this.

当我们和后台工作人员一起做这种工作时，这很容易，因为后台工作人员有进度变化事件.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.谢谢

when we work with background worker to do this kind of job then it is very easy because background worker has progress change event. so how to handle this kind of situation with Async/Await. if possible guide me with sample code. thanks

推荐答案

示例代码来自 文章

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，您将有不同的 IProgress 基本类型:

If you want to report on each file independently you will have different base type for IProgress:

public Task 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 ...));
}

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