C# 如何使用BackgroundWorker事件RunWorkerCompleted

总之，我已经知道了

BackgroundWorker

在WinForm中处理多线程情况的基本用法。代码结构如下所示

在应用程序的主线程中。只要开始背景工作

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

然后它将触发

DoWork

事件。所以我们可以在那里做点什么

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;
    ......
    // report progress.
    worker.ReportProgress(iProgress);
    ....
}

然后我们只需要处理

ProgressChanged

事件来显示BackgroundWorker的进度

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

DoWork

完成后或发生异常。将触发事件

RunWorkerCompleted

下面是我对这个事件处理的问题。请帮忙复习。谢谢

我注意到在

RunWorkerCompletedEventArgs e

中有一个名为“Result”的属性，它的用途是什么？我如何使用它

是否有可能接收我的自定义异常消息而不是

e.error

？如果有，如何制作

private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if (e.Cancelled == true)
    {
        resultLabel.Text = "Canceled!";
    }
    else if (e.Error != null)
    {
        resultLabel.Text = "Error: " + e.Error.Message;
    }
    else
    {
        resultLabel.Text = e.Result.ToString();
    }
}

---

RunWorkerCompletedEventArgs

中的

Result

属性是您在

DoWork（）

中为

DoWorkEventHandler

的结果属性指定的值

您可以为它分配任何您喜欢的内容，因此可以返回整数、字符串、对象/复合类型等

---

如果在

DoWork（）

中抛出异常，则您可以在

RunWorkerCompletedEventArgs

的

Error

属性中访问该异常。在这种情况下，访问Result属性将导致抛出一个

TargetInvocationException

。

您可以使用Result属性存储来自DoWork的任何结果，并从Completed事件访问它。但如果后台工作进程被取消或引发异常，则无法访问结果。你会发现更多的细节

然后是你使用它的班级

public class MyClassUsingWorker
{
    // have reference to the class where the worker will be running
    private MyWorkerClass mwc = null;

    // run the worker
    public void RunMyWorker()
    {
        mwc = new MyWorkerClass();
        BackgroundWorker backgroundWorker1 = new BackgroundWorker();
        backgroundWorker1.DoWork += new DoWorkEventHandler(mwc.RunStuff);
        backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
        backgroundWorker1.RunWorkerAsync();
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        string strSpecialMessage = mwc.ErrorMessage;

        if (e.Cancelled == true)
        {
            resultLabel.Text = "Canceled!";
        }
        else if (e.Error != null)
        {
            resultLabel.Text = "Error: " + e.Error.Message;
        }
        else
        {
            resultLabel.Text = e.Result.ToString();
        }
    }
}

---

那么

错误
呢？这也是OP要求的。更新的答案。谢谢（在电话上阅读，却错过了）
public class MyClassUsingWorker
{
    // have reference to the class where the worker will be running
    private MyWorkerClass mwc = null;

    // run the worker
    public void RunMyWorker()
    {
        mwc = new MyWorkerClass();
        BackgroundWorker backgroundWorker1 = new BackgroundWorker();
        backgroundWorker1.DoWork += new DoWorkEventHandler(mwc.RunStuff);
        backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
        backgroundWorker1.RunWorkerAsync();
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        string strSpecialMessage = mwc.ErrorMessage;

        if (e.Cancelled == true)
        {
            resultLabel.Text = "Canceled!";
        }
        else if (e.Error != null)
        {
            resultLabel.Text = "Error: " + e.Error.Message;
        }
        else
        {
            resultLabel.Text = e.Result.ToString();
        }
    }
}