通過在WinForm中顯示UI中的消息框（來自backgroundworker）來阻止Workerthread

Question

在我的小測試程序中，我想檢查機器的某些部分，同時更新標籤和進度條（基本上是一個啓動窗體，通知用戶關於機器啓動的進度）。 爲此，我已經閱讀了關於在後臺工作中添加東西以及通過ReportProgress更新UI的信息。這工作正常。

所有部件檢查都是在do-while-loop內完成的，只有在零件檢測成功時纔會執行。如果一個零件檢測成功，則循環結束，並且工作線程移動到下一個零件的下一個循環，直到檢查完所有零件。

現在，如果一個部分有缺陷，並且測試不成功，我想顯示一個MessageBox，通知用戶有關缺陷。在這樣做的時候，WorkerThread應該停止，等待用戶按「重試」或「確定」。到目前爲止，無論是新聞發佈會從一開始就開始當前的do-while-loop，直到問題得到解決。 如果我只在我的循環中放入MessageBox.Show（「test」），它會在完成backgroundthread結束後顯示，並在顯示消息框後再次啓動後臺線程。

這裏我的代碼：

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，我怎麼能停止與一個消息框，警告工作者線程，並繼續它（或恢復電流回路）？

Answer 1

您可以使用ReportProgress()方法來報告測試失敗並攔截ProgressChanged事件中您可以顯示消息框的問題。

要使工作線程等待用戶響應，可以使用同步對象，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(); 
      } 
     } 
    } 
}