Question

我正在使用异步等待任务来运行此代码，我想在提取时更改进度条

public async Task<string> DownloadAndExtractFile(string source, string destination, string ItemDownload) //source = File Location //destination = Restore Location
    {
        string zPath = @"C:\Program Files\7-Zip\7zG.exe";
        ProcessStartInfo pro = new ProcessStartInfo();
        pro.WindowStyle = ProcessWindowStyle.Hidden;
        pro.FileName = zPath;
        pro.Arguments = "x \"" + source + "\" -o" + destination;

        await Task.Run(() =>
        {
            Restore.frmRestore.progressBar1.Value = 50; //already set to public
            try
            {
                Process x = Process.Start(pro);
                Task.WaitAll();
                Restore.frmRestore.progressBar1.Value = 100;//already set to public
                x.Close();
                Console.WriteLine("Extract Successful.");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }

        }
           );

        return "Success";
    }

如何在任务运行时更改进度条值。这是错误“跨线程操作无效：控制'progressBar1'从除创建它之外的线程访问。”

Answer 1

Use the Progress<T> type to report progress，正如我在博客中描述的那样：

public async Task<string> DownloadAndExtractFile(string source, string destination, string ItemDownload)
{
  string zPath = @"C:\Program Files\7-Zip\7zG.exe";
  ProcessStartInfo pro = new ProcessStartInfo();
  pro.WindowStyle = ProcessWindowStyle.Hidden;
  pro.FileName = zPath;
  pro.Arguments = "x \"" + source + "\" -o" + destination;

  IProgress<int> progress = new Progress<int>(
      value => { Restore.frmRestore.progressBar1.Value = value; });

  await Task.Run(() =>
  {
    progress.Report(50);
    try
    {
      Process x = Process.Start(pro);
      Task.WaitAll();
      progress.Report(100);
      x.Close();
      Console.WriteLine("Extract Successful.");
    }
    catch (Exception ex)
    {
      Console.WriteLine(ex.ToString());
    }
  });
  return "Success";
}

Answer 2

您可以使用Progress<T>。这允许您通知UI线程您的进度并更新进度条。

所以，在调用该任务的地方，执行此操作：

Progress<int> progress = new Progress<int>(i => Restore.frmRestore.progressBar1.Value = i);
await DownloadAndExtractFile(source, destination, ItemDownload, progress);

在您的方法中，您可以像这样使用progress：

public async Task<string> DownloadAndExtractFile(string source, string destination, string ItemDownload, IProgress<int> progress)
{
    // shortened for clarity
    await Task.Run(() =>
    {
        progress.Report(50);
        try
        {
            Process x = Process.Start(pro);
            Task.WaitAll();
            progress.Report(100);
            x.Close();
            Console.WriteLine("Extract Successful.");
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
    });

    return "Success";
}

注意：您必须将progress作为接口类型IProgress<int>传递才能访问该接口的Report方法。

Answer 3

直接解决方案，但不像Progress<T>那样花哨：

创建一个函数：

private void UpdateProgress(int percent)
{
  if (Restore.frmRestore.progressBar1.InvokeRequired)
  {
    UpdateProgress.Invoke(percent);
  }
  else
  {
    Restore.frmRestore.progressBar1.Value = percent;
  }
}

然后调用它而不是直接设置值。

澄清：.Invoke确实在主线程（即UI-Thread）上执行该函数。

这是1：1你想要的但是我会使用Progress<T>

如何在异步任务运行时更改进度条值

3 个答案: