更新 : 2007 年 11 月
トラップされないスレッドの例外がスローされると、発生します。
名前空間 :
System.Windows.Forms アセンブリ :
System.Windows.Forms (System.Windows.Forms.dll 内)
Public Shared Event ThreadException As ThreadExceptionEventHandler
Dim handler As ThreadExceptionEventHandler
AddHandler Application.ThreadException, handler
public static event ThreadExceptionEventHandler ThreadException
public:
static event ThreadExceptionEventHandler^ ThreadException {
void add (ThreadExceptionEventHandler^ value);
void remove (ThreadExceptionEventHandler^ value);
}
/** @event */
public static void add_ThreadException (ThreadExceptionEventHandler value)
/** @event */
public static void remove_ThreadException (ThreadExceptionEventHandler value)
このイベントにより、Windows フォーム アプリケーションは、Windows フォームのスレッドで発生する未処理の例外を他の方法で処理できます。これらの例外が発生するとアプリケーションは不明な状態に陥るため、これらの例外を処理するには、ThreadException イベントに適切なイベント ハンドラを結び付けてください。可能であれば、構造化例外処理ブロックで例外を処理するようにしてください。
SetUnhandledExceptionMode を設定することにより、このコールバックを Windows フォームのスレッドの未処理の例外に使用するかどうかを変更できます。Windows フォームで作成および所有されていないスレッドで発生する例外をキャッチするには、UnhandledException イベント ハンドラを使用します。
メモ : |
|---|
このイベントを使用するには、Application..::.Run を呼び出す前にハンドラをアタッチする必要があります。 メイン アプリケーション スレッドで例外が発生し、その例外がコール スタックの catch ブロックで処理されない場合、既定の例外ハンドラは、例外をキャッチして、アプリケーションを終了します。アプリケーションのメイン スレッドとは異なるスレッドで例外が発生した場合、そのスレッドは終了しますが、アプリケーションは実行を継続します。 |
注意 : |
|---|
これは静的イベントなので、アプリケーションが破棄されるときにイベント ハンドラをデタッチしないと、メモリ リークが発生します。 |
Windows フォーム スレッドで発生する例外と他のスレッドで発生する例外のイベント ハンドラを設定するコード例を次に示します。このコードでは、アプリケーションのユーザー構成ファイルの設定に関係なく、すべての例外がアプリケーションによって処理されるように SetUnhandledExceptionMode を設定します。ThreadException イベントを使用して UI スレッドの例外が処理され、UnhandledException イベントを使用して UI スレッド以外の例外が処理されます。UnhandledException はアプリケーションが終了することを防止できないので、この例では、終了前にエラーをアプリケーション イベント ログに記録するだけです。
この例は、Form クラスで 2 つの Button コントロール button1 および button2 を定義していることを前提としています。
' 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
// Starts the application.
[SecurityPermission(SecurityAction.Demand, Flags = SecurityPermissionFlag.ControlAppDomain)]
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);
}
// 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 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 );
}
};
// Creates a class to throw the error.
public static class ErrorHandler extends 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 new ArgumentException("The parameter was invalid");
} //button1_Click
public static void main(String[] args)
{
// Creates an instance of the methods that will handle
// the exception.
CustomExceptionHandler eh = new CustomExceptionHandler();
// Adds the event handler to to the event.
Application.add_ThreadException(
new ThreadExceptionEventHandler(eh.OnThreadException));
// Runs the application.
Application.Run(new ErrorHandler());
} //main
} //ErrorHandler
// Creates a class to handle the exception event.
static class CustomExceptionHandler
{
// Handles the exception event.
public void OnThreadException(Object sender, ThreadExceptionEventArgs t)
{
DialogResult result = DialogResult.Cancel;
try {
result = this.ShowThreadExceptionDialog(t.get_Exception());
}
catch (System.Exception exp) {
try {
MessageBox.Show("Fatal Error", "Fatal Error",
MessageBoxButtons.AbortRetryIgnore,
MessageBoxIcon.Stop);
}
finally {
Application.Exit();
}
}
// Exits the program when the user clicks Abort.
if (result.Equals(DialogResult.Abort)) {
Application.Exit();
}
} //OnThreadException
// Creates the error message and displays it.
private DialogResult ShowThreadExceptionDialog(System.Exception e)
{
String errorMsg = "An error occurred please contact the"
+ " administrator with the following information:\n\n";
errorMsg = errorMsg + e.get_Message() + "\n\nStack Trace:\n"
+ e.get_StackTrace();
return MessageBox.Show(errorMsg, "Application Error",
MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Stop);
} //ShowThreadExceptionDialog
} //CustomExceptionHandler
public static void main(String[] args)
{
ErrorHandler.main(args);
}//main
Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
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.NET Framework
サポート対象 : 3.5、3.0、2.0、1.1、1.0
参照