c# BackgroundWorker DoWork 方法调用另一个类和 ProgressReport

Question

我正在运行一个 BackgroundWorker 线程来完成一项耗时的任务。耗时的任务在另一个类(class)。我需要将在 BackgroundWorker 上运行的这个单独类所取得的进展传递回 Main Form1 类。我不确定如何处理这个问题。请提供建议。先感谢您。

    **// Main Form1 UI Class**    

    public void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e)
    {
        //e.Argument always contains whatever was sent to the background worker
        // in RunWorkerAsync. We can simply cast it to its original type.
        DataSet ds = e.Argument as DataSet;
        this.createje.ProcessData(this.ds);
    }

    private void backgroundWorker2_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        this.progressBar1.Minimum = 0;
        this.progressBar1.Maximum = CreateJE.max;
        this.progressBar1.Value = e.Recno;
    }

    **//Other Class called CreateJE**

    public void ProcessData(DataSet ds)
    {
        //Do time consuming task...
     for (int i = 1; i <= 10; i++)
        {
            if (worker.CancellationPending == true)
            {
                e.Cancel = true;
                break;
            }
            else
            {
                // Perform a time consuming operation and report progress.
                System.Threading.Thread.Sleep(500);

                **//How do I report progress back to the Main UI?** 
                //worker.ReportProgress(i * 10);
            }
        }
    }

Answer 1

最干净、最可扩展的解决方案可能是让您的 ProcessData() 方法引发一个事件，BackgroundWorker 正在监听该事件。这样 ProcessData() 不依赖于将 BackgroundWorker 作为调用方。 (您还需要制定一种取消 ProcessData() 的方法)。如果需要，您甚至可以重新使用 ProgressChangedEventArgs。例如(未经测试，但您明白了吗？):

partial class Form1 { 
    public void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e) {
        //e.Argument always contains whatever was sent to the background worker 
        // in RunWorkerAsync. We can simply cast it to its original type.
        DataSet ds = (DataSet)e.Argument;
        var bgw = (BackgroundWorker)sender;

        var eh = new ProgressChangedEventHandler((o,a) => bgw.ReportProgress(a.ProgressPercentage));
        createje.ProgressChanged += eh;
        this.createje.ProcessData(this.ds));
        createje.ProgressChanged -= eh; //necessary to stop listening
    }

    private void backgroundWorker2_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        this.progressBar1.Minimum = 0;
        this.progressBar1.Maximum = CreateJE.max;
        this.progressBar1.Value = e.ProgressPercentage;
    }

}

partial class CreateJE { 

    public event ProgressChangedEventHandler ProgressChanged; 
    protected virtual void OnProgressChanged(ProgressChangedEventArgs e)
    { 
        var hand = ProgressChanged; 
        if(hand != null) hand(this, e);
    }

    public void ProcessData(DataSet ds)
    {
        for(int i = 1; i <= 10; i++)
        {
            // Perform a time consuming operation and report progress.
            System.Threading.Thread.Sleep(500);

            var e = new ProgressChangedEventArgs(i * 10, null);
        }
    }

}

快速而肮脏的方法是将 BackgroundWorker 作为参数传递给 ProcessData()。恕我直言，这是相当丑陋的，但是，将您束缚于仅使用 BackgroundWorkers，并且还强制您在一个地方(主窗体类)定义 BackgroundWorker 并在另一个地方定义 ReportProgress 的返回值(创建 JE 类)。

您还可以使用计时器并每 X 毫秒报告一次进度，查询 CreateJE 对象的进度。这似乎与您的其余代码一致。问题是它会使您的 CreateJE 类不支持多线程。