如何优先点击事件优先

Answer 1

您必须正确等待异步方法。当您调用

Task.Result

时，异步方法将同步执行，因为当前线程正在等待

Result

属性返回。总是

await

async

方法。

你的代码看起来也很臭。不应涉及任何静态属性或实例。您没有提供足够的上下文来理解您在做什么。

class MainWindow : Window
{
  public static HttpClient SharedHttpClient { get; } 
    = new HttpClient();

  private CancellationTokenSource HttpClientCancellationTokenSource { get; set; }

  private async Task UploadAsync(HttpContent content)
  {
    try
    {
      // CancellationTokenSource implements IDisposable!
      // We must dispose it e.g. via the using statement/expression or a finally block or explicitly.
      using this.HttpClientCancellationTokenSource = new CancellationTokenSource();

      string url = GetFileRequestUrl();

      // await the async method. Now the user can click the button and execute the cancel operation 
      // *while* the upload is running.
      await MainWindow.SharedHttpClient.PostAsync(url, content, this.HttpClientCancellationTokenSource.Token);
    }
    catch(OperationCanceledException)
    {
      // Somebody has cancelled the async task.
      // TODO::Perform rollback, cleanup etc.

      // To allow the caller of this operation to handle cancellation too 
      // you can rethrow the exception or swallow it
      //throw;
    }
    finally
    {
      // this.HttpClientCancellationTokenSource is already disposed at this point (using expression).
      // Set variable to NULL so nobody can accidently try to use the disposed instance
      this.HttpClientCancellationTokenSource = null;
    }
  }

  private async void CancelUpload_OnClick(object sender, RoutedEventArgs e)
    => this.HttpClientCancellationTokenSource?.Cancel();
}