BackgroundWorker 从不做任何事情？

Question

这是我正在尝试执行的代码，但在逐步执行我的代码时，我从未在显示 progressbar1 的 windows 表单上看到任何指示或更新的进度。这是我第一次尝试让后台工作人员正常工作，我所拥有的只是一个带有一个按钮的 windows 表单，这就是项目中涉及的所有代码。

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    private int i = 0;

     public Form1()
    {
        InitializeComponent();
        backgroundWorker1.WorkerReportsProgress = true;
        backgroundWorker1.WorkerSupportsCancellation = false;
        backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
        backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
        backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
    }

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

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker worker = sender as BackgroundWorker;
        ReadySteadyGo();
        worker.ReportProgress((i * 10));
        FinalizeAndFinish();
        worker.ReportProgress((i * 10));
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        progressBar1.Text = "Done!";
    }

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        progressBar1.Text = (e.ProgressPercentage.ToString() + "%");
    }

    private void ReadySteadyGo()
    {
        Thread.Sleep(100000);
    }
    private void FinalizeAndFinish()
    {
        Thread.Sleep(1000);
    }
}

Answer 1

我在 Visual Studio 中重新创建了您的示例，并且在 backgroundWorker1_DoWork 中遇到了断点，因此多线程工作正常，您只需要进行适当的处理？

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

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        for (int i = 1; i <= 100; i++)
        {
            backgroundWorker1.ReportProgress(i);
            Thread.Sleep(100);
        }
    }

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

Answer 2

看来您正在使用 Thread.Sleep() 来模拟一个 long-运行操作。根据您的代码示例，您应该考虑以下几点：

当 backgroundWorker1.RunWorkerAsync(); 执行时，它开始在另一个线程上工作。因此，如果您正在交互式调试并且没有在 backgroundWorker1_DoWork 方法中设置断点，则您不太可能看到此代码执行。

当 Thread.Sleep(100000) 执行时，这实际上意味着后台工作程序将暂停 100 秒 - 因此您需要确保至少等待那么长时间查看 UI 更新。

此外，根据 Hans Passant 的评论，请考虑以下几点：

Nor can you see it doing anything, there's no point to assigning the ProgressBar.Text property since it doesn't display text. Set Value instead.

BackgroundWorker 从不做任何事情？

BackgroundWorker never does anything?

c#

backgroundworker