Dowork完成后，背景工人runworkercompleted IS不被称为

Question

我正在创建一个简单的程序，该程序ping我们网络上的所有服务器，并返回Ping请求是否成功。

我正在尝试使用背景工人，以便用户可以按ping按钮，而ping则在后台运行，而他们可以在UI

Dowork上执行其他操作，没有循环可以将其保留在那里，并且可以将其保留在那里，并且可以到达它行：

r = pinger.send（s）

，然后从我的理解中结束，因此应调用runworkCompletept的方法？

长时间的潜落后，我正在重新学习编程，所以如果我错过了一些明显的东西，我深表歉意 ...

   public Form1()
    {

        InitializeComponent();
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = true;
        backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
    }

    private void Ping_Btn_Click(object sender, EventArgs e)
    {

        count = Convert.ToInt32(pingSeconds_TxtBox.Text);

        if (backgroundWorker1.IsBusy != true)
        {
            // Start operation
            backgroundWorker1.RunWorkerAsync();
        }
       
    }

    private static void OnTimedEvent(Object source, ElapsedEventArgs e)
    {
        BackgroundWorker worker = new BackgroundWorker();
        worker.WorkerSupportsCancellation = true;
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker worker = sender as BackgroundWorker;

        if(worker.CancellationPending == true)
        {
            e.Cancel = true;
        }
        else
        {
            for(int i = 0; i <= count; i++)
            {
                MessageBox.Show("something is happening");
                // Create ping object
                Ping pinger = new Ping();
                PingReply r;
                // IP to test ping
                string s = "###";

                try
                {
                    r = pinger.Send(s);

                }
                catch (Exception b)
                {
                    MessageBox.Show(b.ToString());
                }
            }
        }
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        MessageBox.Show("Show me something");

        if(e.Cancelled == true)
        {
            statusLbl1.Text = "Cancelled";
        } else if(e.Error != null)
        {
            statusLbl1.Text = "Error: " + e.Error.Message;
        } else
        {
            statusLbl1.Text = "YEEEEEEEET";
        }
    }

... ...

Answer 1

您需要将backgroundWorker1_runworkercompleted事件处理程序附加到runworkerCompleted事件。 C＃编译器不会根据命名约定将事件挂钩。您必须明确地进行。

public Form1()
{
    InitializeComponent();
    backgroundWorker1.WorkerReportsProgress = true;
    backgroundWorker1.WorkerSupportsCancellation = true;
    backgroundWorker1.DoWork += backgroundWorker1_DoWork;
    backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
}

Answer 2

我强烈建议您将此代码转换为使用async 等待，它在表示代码控制的流程方面要好得多，而不是使用旧的backgroundworker这基本上是贬低的。

注意以下注意：

• 主事件处理程序应为async void，但所有其他异步功能都应为async Task。
• 使用Semaphoreslim.waitasync（0）检查我们是否忙。
• ping对象需要或最后将其处置，concellationTokenSource也是如此。
• ＆lt; = count看起来应该是＆lt;计数因为您从0开始。

SemaphoreSlim sem = new SemaphoreSlim(1, 1);
CancellationToken token;

private async void Ping_Btn_Click(object sender, EventArgs e)
{
    if (!await sem.WaitAsync(0))
        return;

    var tokenSource = new CancellationTokenSource();
    try
    {
        var count = Convert.ToInt32(pingSeconds_TxtBox.Text);
        await RunPingsAsync(count, tokenSource.Token);
        statusLbl1.Text = "YEEEEEEEET";
    }
    catch (OperationCanceledException)
    {
        statusLbl1.Text = "Cancelled";
    }
    catch (Exception e)
    {
        statusLbl1.Text = "Error: " + e.Error.Message;
    }
    finally
    {
        sem.Release();
        tokenSource.Dispose();
    }
        
    MessageBox.Show("Show me something");
}

private Task RunPingsAsync(int count, CancellationToken token)
{
    for(int i = 0; i < count; i++)
    {
        token.ThrowIfCancellationRequested();

        MessageBox.Show("something is happening");
        // IP to test ping
        string s = "###";

        // Create ping object
        using (Ping pinger = new Ping())
        {
            var r = await pinger.SendPingAsync(s);
        }
    }
}

Answer 3

如果要保留无限循环，则必须在背景worker1_dowork方法中进行循环。 也这样的事情

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = (BackgroundWorker) sender;
    while (!worker.CancellationPending)
    {
        //Do your stuff here
        for(int i = 0; i <= count; i++)
        {
            MessageBox.Show("something is happening");
            // Create ping object
            Ping pinger = new Ping();
            PingReply r;
            // IP to test ping
            string s = "###";

            try
            {
                r = pinger.Send(s);

            }
            catch (Exception b)
            {
                MessageBox.Show(b.ToString());
            }
        }
    }        
 }

也是一个好主意，从您的背景线程中显示消息框，将其记录在控制台或任何文件中。