Application.ThreadException Kejadian

Referensi

Definisi

Ruang nama:: System.Windows.Forms

Rakitan:: System.Windows.Forms.dll

Penting

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Terjadi ketika pengecualian utas yang tidak ditarik dilemparkan.

public:
 static event System::Threading::ThreadExceptionEventHandler ^ ThreadException;

public static event System.Threading.ThreadExceptionEventHandler ThreadException;

public static event System.Threading.ThreadExceptionEventHandler? ThreadException;

member this.ThreadException : System.Threading.ThreadExceptionEventHandler

Public Shared Custom Event ThreadException As ThreadExceptionEventHandler

Jenis Acara

ThreadExceptionEventHandler

Contoh

Contoh kode berikut menetapkan penanganan aktivitas untuk pengecualian yang terjadi pada utas Formulir Windows dan pengecualian yang terjadi pada utas lain. Ini diatur SetUnhandledExceptionMode sehingga semua pengecualian ditangani oleh aplikasi, terlepas dari pengaturan dalam file konfigurasi pengguna aplikasi. Ini menggunakan ThreadException peristiwa untuk menangani pengecualian utas UI, dan UnhandledException peristiwa untuk menangani pengecualian utas non-UI. Karena UnhandledException tidak dapat mencegah aplikasi dihentikan, contohnya hanya mencatat kesalahan dalam log peristiwa aplikasi sebelum penghentian.

Contoh ini mengasumsikan bahwa Anda telah menentukan dua Button kontrol, button1 dan button2, di kelas Anda Form .

   // Creates a class to throw the error.
public:
   ref class ErrorHandler: public System::Windows::Forms::Form
   {
      // Inserts the code to create a form with a button.

      // Programs the button to throw an exception when clicked.
   private:
      void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
      {
         throw gcnew ArgumentException( "The parameter was invalid" );
      }

   public:
      static void Main()
      {
         // Creates an instance of the methods that will handle the exception.
         CustomExceptionHandler ^ eh = gcnew CustomExceptionHandler;
         
         // Adds the event handler to the event.
         Application::ThreadException += gcnew ThreadExceptionEventHandler( eh, &Form1::CustomExceptionHandler::OnThreadException );
         
         // Runs the application.
         Application::Run( gcnew ErrorHandler );
      }
   };

   // Creates a class to handle the exception event.
internal:
   ref class CustomExceptionHandler
   {
      // Handles the exception event.
   public:
      void OnThreadException( Object^ /*sender*/, ThreadExceptionEventArgs^ t )
      {
         System::Windows::Forms::DialogResult result = ::DialogResult::Cancel;
         try
         {
            result = this->ShowThreadExceptionDialog( t->Exception );
         }
         catch ( Exception^ ) 
         {
            try
            {
               MessageBox::Show( "Fatal Error", "Fatal Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
            }
            finally
            {
               Application::Exit();
            }
         }
         
         // Exits the program when the user clicks Abort.
         if ( result == ::DialogResult::Abort )
         {
            Application::Exit();
         }
      }

      // Creates the error message and displays it.
   private:
      System::Windows::Forms::DialogResult ShowThreadExceptionDialog( Exception^ e )
      {
         String^ errorMsg = "An error occurred please contact the adminstrator with the following information:\n\n";
         errorMsg = String::Concat( errorMsg, e->Message, "\n\nStack Trace:\n", e->StackTrace );
         return MessageBox::Show( errorMsg, "Application Error", MessageBoxButtons::AbortRetryIgnore, MessageBoxIcon::Stop );
      }
   };

Thread newThread = null;

// Starts the application.
public static void Main(string[] args)
{
    // Add the event handler for handling UI thread exceptions to the event.
    Application.ThreadException += new ThreadExceptionEventHandler(ErrorHandlerForm.Form1_UIThreadException);

    // Set the unhandled exception mode to force all Windows Forms errors to go through
    // our handler.
    Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);

    // Add the event handler for handling non-UI thread exceptions to the event.
    AppDomain.CurrentDomain.UnhandledException +=
        new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);

    // Runs the application.
    Application.Run(new ErrorHandlerForm());
}

// Programs the button to throw an exception when clicked.
private void button1_Click(object sender, System.EventArgs e)
{
    throw new ArgumentException("The parameter was invalid");
}

// Start a new thread, separate from Windows Forms, that will throw an exception.
private void button2_Click(object sender, System.EventArgs e)
{
    ThreadStart newThreadStart = new ThreadStart(newThread_Execute);
    newThread = new Thread(newThreadStart);
    newThread.Start();
}

// The thread we start up to demonstrate non-UI exception handling.
void newThread_Execute()
{
    throw new Exception("The method or operation is not implemented.");
}

// Handle the UI exceptions by showing a dialog box, and asking the user whether
// or not they wish to abort execution.
private static void Form1_UIThreadException(object sender, ThreadExceptionEventArgs t)
{
    DialogResult result = DialogResult.Cancel;
    try
    {
        result = ShowThreadExceptionDialog("Windows Forms Error", t.Exception);
    }
    catch
    {
        try
        {
            MessageBox.Show("Fatal Windows Forms Error",
                "Fatal Windows Forms Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop);
        }
        finally
        {
            Application.Exit();
        }
    }

    // Exits the program when the user clicks Abort.
    if (result == DialogResult.Abort)
        Application.Exit();
}

// Handle the UI exceptions by showing a dialog box, and asking the user whether
// or not they wish to abort execution.
// NOTE: This exception cannot be kept from terminating the application - it can only
// log the event, and inform the user about it.
private static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
{
    try
    {
        Exception ex = (Exception)e.ExceptionObject;
        string errorMsg = "An application error occurred. Please contact the adminstrator " +
            "with the following information:\n\n";

        // Since we can't prevent the app from terminating, log this to the event log.
        if (!EventLog.SourceExists("ThreadException"))
        {
            EventLog.CreateEventSource("ThreadException", "Application");
        }

        // Create an EventLog instance and assign its source.
        EventLog myLog = new EventLog();
        myLog.Source = "ThreadException";
        myLog.WriteEntry(errorMsg + ex.Message + "\n\nStack Trace:\n" + ex.StackTrace);
    }
    catch (Exception exc)
    {
        try
        {
            MessageBox.Show("Fatal Non-UI Error",
                "Fatal Non-UI Error. Could not write the error to the event log. Reason: "
                + exc.Message, MessageBoxButtons.OK, MessageBoxIcon.Stop);
        }
        finally
        {
            Application.Exit();
        }
    }
}

// Creates the error message and displays it.
private static DialogResult ShowThreadExceptionDialog(string title, Exception e)
{
    string errorMsg = "An application error occurred. Please contact the adminstrator " +
        "with the following information:\n\n";
    errorMsg = errorMsg + e.Message + "\n\nStack Trace:\n" + e.StackTrace;
    return MessageBox.Show(errorMsg, title, MessageBoxButtons.AbortRetryIgnore,
        MessageBoxIcon.Stop);
}

Private newThread As Thread = Nothing

' Starts the application. 
<SecurityPermission(SecurityAction.Demand, Flags:=SecurityPermissionFlag.ControlAppDomain)> _
Public Shared Sub Main()
    ' Add the event handler for handling UI thread exceptions to the event.
    AddHandler Application.ThreadException, AddressOf ErrorHandlerForm.Form1_UIThreadException

    ' Set the unhandled exception mode to force all Windows Forms errors to go through
    ' our handler.
    Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException)

    ' Add the event handler for handling non-UI thread exceptions to the event. 
    AddHandler AppDomain.CurrentDomain.UnhandledException, AddressOf CurrentDomain_UnhandledException

    ' Runs the application.
    Application.Run(New ErrorHandlerForm())
End Sub


' Programs the button to throw an exception when clicked.
Private Sub button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
    Throw New ArgumentException("The parameter was invalid")
End Sub

' Start a new thread, separate from Windows Forms, that will throw an exception.
Private Sub button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button2.Click
    Dim newThreadStart As New ThreadStart(AddressOf newThread_Execute)
    newThread = New Thread(newThreadStart)
    newThread.Start()
End Sub


' The thread we start up to demonstrate non-UI exception handling. 
Sub newThread_Execute()
    Throw New Exception("The method or operation is not implemented.")
End Sub


' Handle the UI exceptions by showing a dialog box, and asking the user whether
' or not they wish to abort execution.
Private Shared Sub Form1_UIThreadException(ByVal sender As Object, ByVal t As ThreadExceptionEventArgs)
    Dim result As System.Windows.Forms.DialogResult = _
        System.Windows.Forms.DialogResult.Cancel
    Try
        result = ShowThreadExceptionDialog("Windows Forms Error", t.Exception)
    Catch
        Try
            MessageBox.Show("Fatal Windows Forms Error", _
                "Fatal Windows Forms Error", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop)
        Finally
            Application.Exit()
        End Try
    End Try

    ' Exits the program when the user clicks Abort.
    If result = DialogResult.Abort Then
        Application.Exit()
    End If
End Sub

' Handle the UI exceptions by showing a dialog box, and asking the user whether
' or not they wish to abort execution.
' NOTE: This exception cannot be kept from terminating the application - it can only 
' log the event, and inform the user about it. 
Private Shared Sub CurrentDomain_UnhandledException(ByVal sender As Object, _
ByVal e As UnhandledExceptionEventArgs)
    Try
        Dim ex As Exception = CType(e.ExceptionObject, Exception)
        Dim errorMsg As String = "An application error occurred. Please contact the adminstrator " & _
            "with the following information:" & ControlChars.Lf & ControlChars.Lf

        ' Since we can't prevent the app from terminating, log this to the event log.
        If (Not EventLog.SourceExists("ThreadException")) Then
            EventLog.CreateEventSource("ThreadException", "Application")
        End If

        ' Create an EventLog instance and assign its source.
        Dim myLog As New EventLog()
        myLog.Source = "ThreadException"
        myLog.WriteEntry((errorMsg + ex.Message & ControlChars.Lf & ControlChars.Lf & _
            "Stack Trace:" & ControlChars.Lf & ex.StackTrace))
    Catch exc As Exception
        Try
            MessageBox.Show("Fatal Non-UI Error", "Fatal Non-UI Error. Could not write the error to the event log. " & _
                "Reason: " & exc.Message, MessageBoxButtons.OK, MessageBoxIcon.Stop)
        Finally
            Application.Exit()
        End Try
    End Try
End Sub


' Creates the error message and displays it.
Private Shared Function ShowThreadExceptionDialog(ByVal title As String, ByVal e As Exception) As DialogResult
    Dim errorMsg As String = "An application error occurred. Please contact the adminstrator " & _
 "with the following information:" & ControlChars.Lf & ControlChars.Lf
    errorMsg = errorMsg & e.Message & ControlChars.Lf & _
 ControlChars.Lf & "Stack Trace:" & ControlChars.Lf & e.StackTrace

    Return MessageBox.Show(errorMsg, title, MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop)
End Function

Keterangan

Kejadian ini memungkinkan aplikasi Formulir Windows Anda untuk menangani pengecualian yang tidak tertangani yang terjadi di utas Formulir Windows. Lampirkan penanganan aktivitas Anda ke ThreadException acara untuk menangani pengecualian ini, yang akan membuat aplikasi Anda dalam status tidak diketahui. Jika memungkinkan, pengecualian harus ditangani oleh blok penanganan pengecualian terstruktur.

Anda dapat mengubah apakah panggilan balik ini digunakan untuk pengecualian utas Formulir Windows yang tidak tertangani dengan mengatur SetUnhandledExceptionMode. Untuk menangkap pengecualian yang terjadi di utas yang tidak dibuat dan dimiliki oleh Formulir Windows, gunakan penanganan UnhandledException aktivitas.

Catatan

Untuk menjamin bahwa tidak ada aktivasi acara ini yang terlewatkan, Anda harus melampirkan handler sebelum Anda memanggil Application.Run.

Catatan

Hanya satu handler yang dapat dilampirkan ke kejadian ini. Jika beberapa handler ditambahkan, hanya handler yang terakhir ditambahkan yang akan dipanggil pada pengecualian yang tidak tertangani.

Perhatian

Karena ini adalah peristiwa statis, Anda harus melepaskan penanganan aktivitas Anda ketika aplikasi Anda dibuang, atau kebocoran memori akan dihasilkan.

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