通过在WinForm中显示UI中的消息框（来自backgroundworker）来阻止Workerthread

Question

在我的小测试程序中，我想检查机器的某些部分，同时更新标签和进度条（基本上是一个启动窗体，通知用户关于机器启动的进度）。 为此，我已经阅读了关于在后台工作中添加东西以及通过ReportProgress更新UI的信息。这工作正常。

所有部件检查都是在do-while-loop内完成的，只有在零件检测成功时才会执行。如果一个零件检测成功，则循环结束，并且工作线程移动到下一个零件的下一个循环，直到检查完所有零件。

现在，如果一个部分有缺陷，并且测试不成功，我想显示一个MessageBox，通知用户有关缺陷。在这样做的时候，WorkerThread应该停止，等待用户按“重试”或“确定”。到目前为止，无论是新闻发布会从一开始就开始当前的do-while-loop，直到问题得到解决。 如果我只在我的循环中放入MessageBox.Show（“test”），它会在完成backgroundthread结束后显示，并在显示消息框后再次启动后台线程。

这里我的代码：

namespace USBSerialTest 
{ 
public partial class test1 : Form 
{ 
    private int check; 
    private int Progress; 

    private byte[] Check_byte_Board1 = { 0x02, 0x01, 0x64, 0x06, 0x00, 0x00, 0x00, 0x80, 0xed }; 
    private byte[] Check_byte_Board2 = { 0x02, 0x01, 0x64, 0x06, 0x00, 0x00, 0x00, 0x81, 0xee }; 

    public test1() 
    { 
     InitializeComponent(); 
     Shown += new EventHandler(test1_LoadForm); 
     backgroundWorker1.WorkerReportsProgress = true; 
     backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork); 
     backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged); 

     //backgroundWorker1.ProgressChanged += ShowWarning; Not working 
    } 
    void test1_LoadForm(object sender, EventArgs e) 
    { 
     backgroundWorker1.RunWorkerAsync(); 
    } 

    void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
    { 
     Progress = 0; 
     backgroundWorker1.ReportProgress(Progress, "Checking for Board Function"); 
     do               //check if Board retruns an error 
     { 
      Motor.Instance.Check_Board(); 
      if (Motor.Instance.buf.SequenceEqual(Check_byte_Board1) || Motor.Instance.buf.SequenceEqual(Check_byte_Board2)) 
      { 
       check = 1; 
       Progress += 10; 
       //MessageBox.Show("test"); not working, just for testing here 
       backgroundWorker1.ReportProgress(Progress, "Checking for Board Function"); 

      } 
      else 
      { 
       //here is the important part, when there is an error, I want to display the warning message 
       //and start the do-while loop from the start, all other message boxes where just to 
       //test around if the general principle works 
       DialogResult result = MessageBox.Show("Boarddriver produce Errorcode ... Please Consult"); 
       if (result == DialogResult.Retry) 
       { 
        check = 0; 
       } 
       else 
       { 
        check = 0; 
       } 
      } 
     } while (check != 1); 
     backgroundWorker1.ReportProgress(Progress, "Succes");   
    } 
    // Back on the 'UI' thread so we can update the progress bar 
    void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
    { 
     progressBar1.Value = e.ProgressPercentage; 
     label1.Text = e.UserState.ToString(); 
     //MessageBox.Show(e.UserState.ToString()); not working 
    } 

    private static void ShowWarning(object sender, ProgressChangedEventArgs e) 
    { 
     MessageBox.Show("test box"); //not working, displays a Messagebox each time 
     //ProgressChanged is triggered, but does not block the worker thread. 
    } 
} 
} 

所以，我怎么能停止与一个消息框，警告工作者线程，并继续它（或恢复电流回路）？

Answer 1

您可以使用ReportProgress()方法来报告测试失败并拦截ProgressChanged事件中您可以显示消息框的问题。

要使工作线程等待用户响应，可以使用同步对象，例如AutoResetEvent。

namespace USBSerialTest 
{ 
    public partial class test1 : Form 
    { 
     private int check; 
     private int Progress; 
     private MessageBoxResult UserDecision; 
     private AutoResetEvent UserDecidedEvent = new AutoResetEvent(false); 
     private string ErrorCode; 

     private byte[] Check_byte_Board1 = { 0x02, 0x01, 0x64, 0x06, 0x00, 0x00, 0x00, 0x80, 0xed }; 
     private byte[] Check_byte_Board2 = { 0x02, 0x01, 0x64, 0x06, 0x00, 0x00, 0x00, 0x81, 0xee }; 

     public test1() 
     { 
      InitializeComponent(); 
      Shown += new EventHandler(test1_LoadForm); 
      backgroundWorker1.WorkerReportsProgress = true; 
      backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork); 
      backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged); 

      //backgroundWorker1.ProgressChanged += ShowWarning; Not working 
     } 
     void test1_LoadForm(object sender, EventArgs e) 
     { 
      backgroundWorker1.RunWorkerAsync(); 
     } 

     void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
     { 
      Progress = 0; 
      backgroundWorker1.ReportProgress(Progress, "Checking for Board Function"); 
      do               //check if Board retruns an error 
      { 
       Motor.Instance.Check_Board(); 
       if (Motor.Instance.buf.SequenceEqual(Check_byte_Board1) || Motor.Instance.buf.SequenceEqual(Check_byte_Board2)) 
       { 
        check = 1; 
        Progress += 10; 
        //MessageBox.Show("test"); not working, just for testing here 
        backgroundWorker1.ReportProgress(Progress, "Checking for Board Function"); 

       } 
       else 
       { 
        //here is the important part, when there is an error, I want to display the warning message 
        //and start the do-while loop from the start, all other message boxes where just to 
        //test around if the general principle works 
        ErrorCode = "Boarddriver produce Errorcode ... Please Consult"; 
        backgroundWorker1.ReportProgress(Progress, ErrorCode); 

        UserDecidedEvent.WaitOne(); 

        if (UserDecision != DialogResult.Retry) 
        { 
         check = 1; 
         // Rewind checking of the board here to try the same 
         // action again when calling Motor.Instance.Check_Board() 
        } 
        else 
        { 
         check = 0; 
        } 
       } 
      } while (check != 1); 
      backgroundWorker1.ReportProgress(Progress, "Succes"); 
     } 
     // Back on the 'UI' thread so we can update the progress bar 
     void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
     { 
      if (e.UserState == ErrorCode) 
      { 
       UserDecision = MessageBox.Show("Boarddriver produce Errorcode ... Please Consult"); 
       UserDecidedEvent.Set(); 
      } 
      else 
      { 
       progressBar1.Value = e.ProgressPercentage; 
       label1.Text = e.UserState.ToString(); 
      } 
     } 
    } 
}