[C#][VB.NET]自定義例外對話框

之前在『例外處理使用時機』這篇有提到我目前很少會寫例外處理。除了在那篇提到的原因之外,還有個因素就是我會弄個自定義的例外處理視窗,讓使用者在例外發生時,可以匯出例外訊息並提供給開發人員。有了匯出的例外訊息,我們就可以很快的把未處理完的例外(指給程式員看的例外)給修正。

要做到自定義的例外對話框,我們需要利用Application.ThreadException事件。

先讓我們看一下MSDN的說明:

image

從MSDN的說明可以很清楚的看到,當執行緒發生例外,且該例外未被處理,則該事件即會觸發。

接著就讓我們來看看如何才能利用該事件做出自定義的例外對話框。首先,我們需要設計自定義的例外對話框。

image

接著撰寫繫上事件用的副程式。

VB.NET

    Public Shared Sub ShowBugWindowOnError()


        AddHandler Application.ThreadException, AddressOf OnErrorOccur


    End Sub



C#


    public static void ShowBugWindowOnError()


    {


        Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(OnErrorOccur);


    }   

最後寫上事件觸發時要執行的事件處理函式。

VB.NET


    Protected Shared Sub OnErrorOccur(ByVal sender As Object, ByVal e As ThreadExceptionEventArgs)


        Dim errorDlg As New ExceptionDialog


        errorDlg.DetailErrorMsg_TextBox.Text = GetDetailErrorMsg(e.Exception)


        errorDlg.ShowDialog()


    End Sub

C#


    protected static void OnErrorOccur(object sender, System.Threading.ThreadExceptionEventArgs e)


    {


        ExceptionDlg errorDlg = new ExceptionDlg();


        errorDlg.DetailErrorMsg_TextBox.Text = GetDetailErrorMsg(e.Exception);


        errorDlg.ShowDialog();


    }

到此一個簡單的自定義例外對話框就完成了。使用上,我們只需呼叫剛寫的繫上事件用副程式即可。

VB.NET



   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load


        ExceptionDialog.ShowBugWindowOnError()


    End Sub


C#


    private void Form1_Load(object sender, EventArgs e)


    {


        ExceptionDlg.ShowBugWindowOnError();


    }

完整程式碼:

VB.NET



Imports System.Windows.Forms


Imports System.Threading


Imports System.Text


 


Public Class ExceptionDialog


 


#Region “Const”


    Const OpenDetailButtonText As String = “v 詳細資料”


    Const CloseDetailButtonText As String = “^ 詳細資料”


#End Region


 


 


 


#Region “Var”


    Private _isDetailOpened As Boolean


#End Region


 


 


 


#Region “Public Shared Method”


 


    *


    ‘Author: Larry Nung


    ‘Date: 2009/4/9


    ‘Purpose: 


    ‘Memo: 


    *


    ‘’’ <summary>


    ‘’’ Shows the bug window on error.


    ‘’’ </summary>


    ‘’’ <remarks></remarks>


    Public Shared Sub ShowBugWindowOnError()


        AddHandler Application.ThreadException, AddressOf OnErrorOccur


    End Sub


#End Region


 


 


#Region “Protected Shared Method”


 


    *


    ‘Author: Larry Nung


    ‘Date: 2009/4/9


    ‘Purpose: 


    ‘Memo: 


    *


    ‘’’ <summary>


    ‘’’ Called when [error occur].


    ‘’’ </summary>


    ‘’’ <param name=”sender”>The sender.</param>


    ‘’’ <param name=”e”>The <see cref=”System.Threading.ThreadExceptionEventArgs” /> instance containing the event data.</param>


    ‘’’ <remarks></remarks>


    Protected Shared Sub OnErrorOccur(ByVal sender As Object, ByVal e As ThreadExceptionEventArgs)


        Dim errorDlg As New ExceptionDialog


        errorDlg.DetailErrorMsg_TextBox.Text = GetDetailErrorMsg(e.Exception)


        errorDlg.ShowDialog()


    End Sub


#End Region


 


 


#Region “Private Shared Method”


 


    *


    ‘Author: Larry Nung


    ‘Date: 2009/4/9


    ‘Purpose: 


    ‘Memo: 


    *


    ‘’’ <summary>


    ‘’’ Gets the detail error MSG.


    ‘’’ </summary>


    ‘’’ <returns></returns>


    ‘’’ <remarks></remarks>


    Private Shared Function GetDetailErrorMsg(ByVal e As Exception) As String


        Dim str As New StringBuilder


        str.AppendLine(String.Format(“Source: {0}”, e.Source))


        str.AppendLine(String.Format(“Message: {0}”, e.Message))


        str.AppendLine(String.Format(“TargetSite: {0}”, e.TargetSite))


        str.AppendLine(“”)


        str.AppendLine(“StackTrace: “)


        str.AppendLine(e.StackTrace)


        Return str.ToString


    End Function


#End Region


 


 


 


 


 


#Region “Event Process”


    Private Sub OK_Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK_Button.Click


        Me.DialogResult = System.Windows.Forms.DialogResult.OK


        Me.Close()


    End Sub


 


    Private Sub Cancel_Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Cancel_Button.Click


        Me.DialogResult = System.Windows.Forms.DialogResult.Cancel


        Application.Exit()


    End Sub


 


    Private Sub Detail_Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Detail_Button.Click


        _isDetailOpened = Not _isDetailOpened


        Detail_Button.Text = If(_isDetailOpened, CloseDetailButtonText, OpenDetailButtonText)


        Me.Height = If(_isDetailOpened, Me.DetailErrorMsg_TextBox.Bottom, Me.DetailErrorMsg_TextBox.Top) + 32


    End Sub


 


    Private Sub ExceptionDialog_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load


        Me.Height = Me.DetailErrorMsg_TextBox.Top + 32


        Me.ErrorIcon_Label.Image = SystemIcons.Error.ToBitmap


    End Sub


#End Region


 


End Class


C#



using System;


using System.Collections.Generic;


using System.ComponentModel;


using System.Data;


using System.Drawing;


using System.Linq;


using System.Text;


using System.Windows.Forms;


 


 


namespace ExceptionDlgTest


{


    public partial class ExceptionDlg : Form


    {


 


        #region Const


        const string OpenDetailButtonText = “v 詳細資料”;


        const string CloseDetailButtonText = “^ 詳細資料”;


        #endregion


 


        #region Var


        private Boolean _isDetailOpened;


        #endregion


 


 


        #region Construction


        public ExceptionDlg()


        {


            InitializeComponent();


        }


        #endregion


 


 


 


        #region Public Shared Method


 


        //*


        //Author: Larry Nung


        //Date: 2009/4/9


        //Purpose: 


        //Memo: 


        //*


        /// <summary>


        /// 


        /// </summary>


        public static void ShowBugWindowOnError()


        {


            Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(OnErrorOccur);


        }     


        #endregion


 


 


        #region Protected Shared Method


        protected static void OnErrorOccur(object sender, System.Threading.ThreadExceptionEventArgs e)


        {


            ExceptionDlg errorDlg = new ExceptionDlg();


            errorDlg.DetailErrorMsg_TextBox.Text = GetDetailErrorMsg(e.Exception);


            errorDlg.ShowDialog();


        }


        #endregion


 


 


        #region Private Shared Method


        private static string GetDetailErrorMsg(Exception e)


        {


            StringBuilder str = new StringBuilder();


            str.AppendLine(String.Format(“Source: {0}”, e.Source));


            str.AppendLine(String.Format(“Message: {0}”, e.Message));


            str.AppendLine(String.Format(“TargetSite: {0}”, e.TargetSite));


            str.AppendLine(“”);


            str.AppendLine(“StackTrace: “);


            str.AppendLine(e.StackTrace);


            return str.ToString();


        }


        #endregion


 


 


        #region Event Process


        private void Cancel_Button_Click(object sender, EventArgs e)


        {


            Application.Exit();


        }


 


        private void OK_Button_Click(object sender, EventArgs e)


        {


            this.Close();


        }


 


        private void Detail_Button_Click(object sender, EventArgs e)


        {


            _isDetailOpened = !_isDetailOpened;


            Detail_Button.Text = _isDetailOpened ? CloseDetailButtonText : OpenDetailButtonText;


            this.Height = _isDetailOpened ? this.DetailErrorMsg_TextBox.Bottom : this.DetailErrorMsg_TextBox.Top + 32;


        }


 


        private void ExceptionDlg_Load(object sender, EventArgs e)


        {


            this.Height = this.DetailErrorMsg_TextBox.Top + 32;


            this.ErrorIcon_Label.Image = SystemIcons.Error.ToBitmap();


        }


        #endregion


 


     


    }


}


執行畫面如下:

image

image

Conclusion

透過Application.ThreadException事件,我們可以很容易達到該篇的效果。但需注意這樣的作法只對繫上的執行緒有效,非繫上的執行緒若發生例外,將無法截取到。在實際應用上,也可依自己需求加入記錄到事件記錄簿等功能,甚至可以使用.NET預設的例外視窗來顯示,只是多加了一些自己的處理,讓使用者感覺不出差異。

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
AddHandler Application.ThreadException, AddressOf Application_ThreadException

End Sub

Private Sub Application_ThreadException(ByVal sender As Object, ByVal e As ThreadExceptionEventArgs)

Dim exceptionDlg As New ThreadExceptionDialog(e.Exception)
exceptionDlg.ShowDialog()
End Sub

image

另外,若有興趣的也可以改繫上AppDomain.UnhandledException試看看。

image

Download

ExceptionDlg.zip