用户界面线程块 [英] UI Thread Block

问题描述

我已经创建了一个简单的WPF应用程序，并向默认窗口添加了一个按钮。当我单击该按钮时，将调用一个模拟的Long工作方法(使用Thread.Sept(15000)模拟)。我正在尝试让按钮异步执行。然而，尽管有下面的在线示例，但只要我一单击，按钮和整个窗口就会锁定，并一直保持到线程。睡眠(...)完事了。

您知道为什么会发生这种情况吗？

代码如下：

private void button1_Click(object sender, RoutedEventArgs e)
{
   DoSomeAsyncWork();
}

private void DoSomeAsyncWork()
{
     System.Windows.Threading.Dispatcher.Run();
     Thread thread = new System.Threading.Thread(
         new System.Threading.ThreadStart(
          delegate()
          {
               Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() => Thread.Sleep(15000)));
          }
        ));
     thread.Start();
}

推荐答案

您正在将长操作放回UI线程。让我评论一下你的例子：

Thread thread = new System.Threading.Thread( 
    new System.Threading.ThreadStart( 
        delegate() { 
            // here we are in the background thread

            Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, 
                new Action(() => {
                    // here we are back in the UI thread
                    Thread.Sleep(15000);
                })); 
      } 
    )); 

因此，您应该这样修改您的示例：

Thread thread = new System.Threading.Thread( 
    new System.Threading.ThreadStart( 
        delegate() { 
            // here we are in the background thread

            Thread.Sleep(15000);  // <-- do the long operation here

            Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, 
                new Action(() => {
                    // here we are back in the UI thread

                    // do stuff here that needs to update the UI after the operation finished
                })); 
      } 
    )); 

正如其他人所提到的，使用BackEarth Worker类更容易。下面是一个例子：

private void DoSomeAsyncWork()   
{   
    BackgroundWorker bw = new BackgroundWorker();

    bw.DoWork += (sender, args) => {
        // do your lengthy stuff here -- this will happen in a separate thread
        Thread.Sleep(15000);
    }

    bw.RunWorkerCompleted += (sender, args) => {
        if (args.Error != null)  // if an exception occurred during DoWork,
            MessageBox.Show(args.Error.ToString());  // do your error handling here

        // do any UI stuff after the long operation here
        ...
    }

    bw.RunWorkerAsync(); // start the background worker
}

这篇关于用户界面线程块的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！