BackgroundWorker 不会在 CancelAsync() 上停止并且仅工作一次

我有一种名为 Sorter 的表单。其上有“jademy”按钮，可打开“进度窗口”窗口

private void jademy_Click(object sender, EventArgs e)
{
    ProgressWindow progress = new ProgressWindow();
    progress.ShowDialog();
}

“进度窗口”表格的代码如下：

public partial class ProgressWindow : Form
{
    private BackgroundWorker backgroundWorker = new BackgroundWorker();

    public ProgressWindow()
    {
        InitializeComponent();
        stop.Visible = true;
        ok.Visible = false;
        backgroundWorker.RunWorkerAsync();
        backgroundWorker.WorkerReportsProgress = true;
        backgroundWorker.WorkerSupportsCancellation = true;

        #region block1

        backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
        backgroundWorker.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker_ProgressChanged);
        backgroundWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker_RunWorkerCompleted);

        #endregion
    }

    private void stop_Click(object sender, EventArgs e)
    {
        backgroundWorker.CancelAsync();
    }

    private void ok_Click(object sender, EventArgs e)
    {
        this.Close();
    }

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

    }

    private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        progressBar1.Value = e.ProgressPercentage;
        this.Text = "Done: " + e.ProgressPercentage.ToString() + "%";
    }

    private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        if ((e.Cancelled == true))
        {
            MessageBox.Show("Cancelled", "Message", MessageBoxButtons.OKCancel, MessageBoxIcon.Asterisk);
        }

        else if (!(e.Error == null))
        {
            MessageBox.Show("Error: " + e.Error.Message, "ERROR!", MessageBoxButtons.OKCancel);
        }
        else
        {
            ok.Visible = true;
            stop.Visible = false;
        }
    }
}

现在。我有三个问题。

1. 单击停止按钮不会执行任何操作。似乎“backgroundWorker.CancelAsync()”不会停止该过程。

2. When I close progress window and I want to run it again I have to wait some time before click on 'jademy' button. Otherwise progress window is displayed like this: (and nothing changes) instead of this: It looks like the program "remembers" that work was done even though it is a new instance of ProgressWindow. Notice that on the incorrect version 'OK' button is visible at once - instead of waiting for the completion of the work.

3. 我想澄清“块1”中的代码。说实话我并不完全理解。这部分真的重要吗？我的意思是，我找到了很多例子（也在这个论坛上 - 例如here https://stackoverflow.com/questions/12126889/how-to-use-winforms-progress-bar），其中未包含此部分，并且用户报告该解决方案有效。就我而言，如果没有这部分，进度条根本不起作用，但也许我做错了什么。

1. 调用 CancelAsync 会停止任何挂起的工作。但如果工作已经开始，方法体需要检查是否调用了cancel。看取消异步 https://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.cancelasync%28v=vs.110%29.aspx

CancelAsync 提交终止挂起后台的请求 操作并将 CancellationPending 属性设置为 true。

当您调用 CancelAsync 时，您的工作方法有机会 停止其执行并退出。工作人员代码应定期检查 Cancellation Pending 属性查看它是否已设置为 true。

2. 我对此一无所知。顺便说一句，图像不起作用。将其嵌入到问题中。
3. 该代码分配一个在BackgroundWorker启动时执行的方法，并且您连接方法来报告进度并在后台工作完成后进行清理/更新。