Question

我最近发现了使用Threads在我的应用程序中AutoResetEvent之间的消息传递。在控制台应用程序中，我会进行while(true)循环并依赖AutoResetEvent.WaitOne()等待线程发出信号，例如数据已准备好使用AutoResetEvent.Set()进行处理。我知道如何使用Class在线程之间共享数据，该AutoResetEvent具有工作线程的方法，以及在工作线程和主线程之间共享的数据元素。

我的问题是如何在Winforms应用程序中使用WaitOne()，我通常看不到命令循环。我应该在Winforms应用程序中将Console.ReadLine()调用放在哪里？

关于示例代码：最好的示例是关于如何使signals超时的answer on this site，这基本上是关于如何使用BackgroundWorker的简单示例。该示例是一个控制台应用程序示例。

在使用Google搜索时，我的问题的答案可能是使用{{1}}控件？

Answer 1

根据您的问题，我了解您的UI线程应该等待事件。

WinForms应用程序的UI线程必须将控制权传递给操作系统以允许用户交互，因此等待AutoResetEvent是不合适的。如果要与UI线程通信，可以使用：

bool ret = (bool)myFormInstance.Invoke(
    new Func<DataClass, bool>(myFormInstance.DoStuff), 
    myData);

public class MyForm : Form
{
    public bool DoStuff(DataClass data)
    {
        ....
    }
}

您还可以使用BeginInvoke异步运行UI线程上的代码。

如果你想要相反的东西（UI线程告诉工作线程开始处理）你可以使用BackgroundWorker，应该有很多关于它的教程。

Answer 2

是的，请改用BackgroundWorker。

Answer 3

似乎在Winforms中使用多线程的完整解决方案是将BackgroundWorker和AutoResetEvent结合起来。

如果我是正确的，那么BackgroundWorker就像Thread，其优点是它与ProgressChanged事件处理程序很好地接口，用于从后台线程到UI的信令。对于从UI到后台线程的信令，我们可能仍需要AutoResetEvent。在我的例子中，我想使用Next按钮开始一个新的阻塞调用来接收数据。下面是我刚刚测试的代码。

然而，问题是，如果没有比在这里使用AutoResetEvent更好的方法了。似乎工作得很好。

/// <summary>
/// The Next button uses this to signal the BackgroundWorker
/// to start the blocking call to Receive data
/// </summary>
private AutoResetEvent _SignalStartReceive  = new AutoResetEvent(false);

/// <summary>
/// To implement variable time it takes until Receive returns
/// </summary>
private Random _RandomTime = new Random();

// Class Initializer
public Form()
{
    backgroundWorker_Receive.WorkerReportsProgress = true;
    backgroundWorker_Receive.RunWorkerAsync();
    return;
}

/// <summary>
/// User presses this button when he is ready to Receive the next
/// data packet
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button_ReceiveNext_Click(object sender, EventArgs e)
{
    checkBox_Receive.Checked = true;
    textBox_ReceivedContent.Text = "";
    _SignalStartReceive.Set();
    return;
}

/// <summary>
/// User presses this button when he is ready to Receive the next
/// data packet
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button_ReceiveNext_Click(object sender, EventArgs e)
{
    checkBox_Receive.Checked = true;
    textBox_ReceivedContent.Text = "";
    _SignalStartReceive.Set();
    return;
}

/// <summary>
/// This is the worker thread, running in the background
/// while the UI stays responsive
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void backgroundWorker_Receive_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;
    while (true)
    {
        // blocking: wait for button click
        _SignalStartReceive.WaitOne();
        // blocking: wait for datagram over network
#if true //temporary code to simulate UdpClient.Receive()
        DateTime StartTime = DateTime.Now;
        int RandomTimeMs = 2000 + 30 * _RandomTime.Next(100);
        Thread.Sleep(RandomTimeMs);
        _ReceivedDatagram = string.Format("UDP data ... {0} ms", (DateTime.Now - StartTime).TotalMilliseconds);
#else
        something with UdpClient.Receive();
#endif
        // succeeded:
        worker.ReportProgress(0);//fire the event: Receive_ProgressChanged (argument does not matter)
    }
    //return; //unreachable, but would fire the Completed event
}

/// <summary>
/// Handler for the ReportProgress() call by the BackgroundWorker Thread
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void backgroundWorker_Receive_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    textBox_ReceivedContent.Text = _ReceivedDatagram;
    checkBox_Receive.Checked = false;
    return;
}

如何在WinForms中使用AutoResetEvent

3 个答案: