跨线程操作？ [复制]

Question

第一次我什至不确定 C# Cross-Thread Operation 是什么，所以看到这条调试消息从一开始就让我大吃一惊 - Cross-thread operation not valid: Control 'panel1' accessed from a thread other than the thread it was created on. 我只是想写一个文本框来显示我的程序的进度。为简洁起见，Thread.Sleep() 在下面的代码中使用。当我的代码到达panel1.Controls.Add(txt); 行时，我会收到调试消息，这是完整代码：

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    private DateTime now = DateTime.Now;
    private int i = 0;
    TextBox txt = new TextBox();

     public Form1()
    {
        InitializeComponent();
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = false;
        backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
        backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
    }

    private void button1_Click(object sender, EventArgs e)
    {
            backgroundWorker1.RunWorkerAsync();
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
            panel1.Controls.Add(txt);
            MethodOne();
            MethodTwo();
    }

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        progressBar1.Value = e.ProgressPercentage;
    }

    private void MethodOne()
    {
        txt.Text = "MethodOne Process Has Begun....." + now;
        Thread.Sleep(100);
        txt.Text = "MethodOne Process Has Finished....." + now;
    }
    private void MethodTwo()
    {
        txt.Text = "MethodTwo Process Has Begun....." + now;
        Thread.Sleep(100);
        txt.Text = "MethodTwo Has Finished....." + now;
    }
}
}

如果我需要提供更多详细信息或有关如何设置我的 Windows 窗体的更多信息，请告诉我。

Answer 1

您不能直接从 BackgroundWorker 线程访问 UI 控件。 UI 控件位于单独的线程上，因此会出现错误。这是不允许的：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    panel1.Controls.Add(txt);
    ...
}

BackgroundWorker 允许您传递一个数字（通常代表一个百分比）和另一个对象（可以是任何东西，例如您的文本）。我推荐的是：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    var bgw = (BackgroundWorker)sender;

    bgw.ReportProgress(33, "MethodOne Process Has Begun.....");
    MethodOne();

    bgw.ReportProgress(66, "MethodTwo Process Has Begun.....");
    MethodTwo();

    bgw.ReportProgress(100, "All Processes Finished.");
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;

    var statusMessage = e.UserState.ToString();
    // Display statusMessage in an appropriate control, i.e. a Label
}

Answer 2

从不同线程在 UI 上发生的操作需要一个称为 Invoke 的特殊编组过程。如果不使用其他线程的 Invoke，则会发生错误。