请向我解释一下这个背景工作人员活动

本文关键字：一下 背景 活动 工作人员 解释 | 更新日期: 2023-09-27 17:54:23

我正在试用BackgroundWorker，并试图在每个事件中通知我的主线程。这些事情对我来说都是新的，我想问一下，我做得好吗？

我用以下方式简化了我的winforms问题：(它只有1个按钮，当我按下它时，在另一个线程中计数为10(

public partial class Form1 : Form
{
    public void Subscribe(CountToTen c)
    {
        c.HandleWorkerEvent += new CountToTen.WorkerHandler(OtherThreadFinished);
    }
    private void OtherThreadFinished(CountToTen c, EventArgs e)
    {
        Debug.WriteLine("I'm ready !!!");
    }
    public Form1()
    {
        InitializeComponent();
    }
    private void btn_do_Click(object sender, EventArgs e)
    {
        CountToTen newThread = new CountToTen();
        Subscribe(newThread);
        newThread.StartCountingAndReportIfFinished();
    }
}

CountToTen类：

public class CountToTen
{
    public event WorkerHandler HandleWorkerEvent;
    public EventArgs e;
    public delegate void WorkerHandler(CountToTen c, EventArgs e);
    public void StartCountingAndReportIfFinished()
    {
        BackgroundWorker worker = new BackgroundWorker();
        worker.DoWork += delegate(object s, DoWorkEventArgs args)
        {
            for (int i = 1; i <= 10; i++)
            {
                Thread.Sleep(300);
                Debug.WriteLine("Counting :" + i.ToString());
            }
        };
        worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(delegate(object o, RunWorkerCompletedEventArgs args)
            {
                Debug.WriteLine("Fromt Thread2 : I am finished!");
                if (HandleWorkerEvent != null)
                {
                    HandleWorkerEvent(this, e);
                }
            });
        worker.RunWorkerAsync();
        worker.Dispose();
    }
}

当BW完成时，我正试图创建一个事件，并以我的主表单订阅该事件。它工作得很好，但是，我真的不明白这一行发生了什么：

worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(delegate(object o, RunWorkerCompletedEventArgs args)
            {
                Debug.WriteLine("Fromt Thread2 : I am finished!");
                if (HandleWorkerEvent != null)
                {
                    HandleWorkerEvent(this, e);
                }
            });

当BW完成时，我不是在这里为它创建一个事件，然后为主线程调用另一个事件吗？这不是矫枉过正吗？我也可以直接订阅RunWorkerCompleteEventHandler吗？

我在这里有点困惑，请启蒙一个初学者。感谢

请向我解释一下这个背景工作人员活动

这是对BackgroundWorker的RunWorkerCompleted事件的订阅。您可以使用匿名方法或命名方法来完成此操作。您还可以通过以下方式删除委托类型声明：

worker.RunWorkerCompleted += (o, args) => 
{
    // raise HandleWorkerEvent if there is any subscriber exists
    if (HandleWorkerEvent != null)    
        HandleWorkerEvent(this, e);
    worker.Dispose();
};

使用命名方法，这将看起来像

worker.RunWorkerCompleted += Worker_RunWorkerCompleted;

经办人：

void Worker_RunWorkerCompleted(object o, RunWorkerCompletedEventArgs args)
{
    if (HandleWorkerEvent != null)    
        HandleWorkerEvent(this, e);
    ((BackgroundWorker)o).Dispose();
}

顺便说一句，我觉得上课更好，因为只有倒数十的逻辑。在表单上创建BackgroundWorker，并在DoWork事件处理程序中使用此类。表单还将处理其所有组件。

Am I not creating an event here for my BW, when it is finished,
 and then call the another for the main thread?

是的。。您正在处理CountToTen类中BackgroundWorker的事件。显然，根据您的类架构，通过Event通知主窗体的唯一方法。

  Is it not overkill? Could I subscribe directly to the RunWorkerCompleteEventHandler
  as well?

你当然可以。。您的BackgroundWorker不会直接暴露给主窗体，否则您可以从主窗体本身订阅RunWorkerCompletedEvent。

注意：您不必调用Dispose((它通过Component实现IDisposable接口。有关详细信息，请参阅此处

更新

  • 替代方式

    public partial class Form1 : Form
{
  private void btn_do_Click(object sender, EventArgs e)
  { 
    CountToTen obj= new CountToTen();
     obj.bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
     obj.bw.RunWorkerAsync();
   }
   void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e){}       
}
class CountToTen 
{
public BackgroundWorker bw = new BackgroundWorker();
public CountToTen()
{
    bw.DoWork += new DoWorkEventHandler(bw_DoWork);
}
void bw_DoWork(object sender, DoWorkEventArgs e)
{
    //Do your Stuff
}
}

您可以直接订阅BackgroundWorker的RunWorkerCompleted事件，但这取决于您的业务逻辑和架构。

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