asp.net C # 's exception handling mechanism program code

What a perfect application and a skilled programmer can never make a mistake. Rather than pursuing the perfect, error-free code, it's probably the most valuable thing to do before releasing a program that might have foreseen exceptions. So how does C # handle exceptions? First, we start with the most common anomaly:

Using the try-catch-finally block to catch exceptions, the basic format is as follows:

code is as follows

copy code

Try  {     //Get and use resources, may appear exceptions    catch (dividebyzeroexception de)  {    catch (ArithmeticException ae)  {  }  catch (Exception e)  {     //capture and handle exceptions. When multiple exceptions occur and there is an inheritance relationship between the exception classes (dividebyzeroexception==>arithmeticexception==>exception),      The  //capture order is a subclass before the base class is  }  finally  {     //No matter what the situation is ( The code for the block (such as closing a file) is executed even if it is return in a catch block     //It is also necessary to use any break, continue in the finally block, Return exit is illegal.  }

Asp. NET exception handling

In addition to the above try-catch-finally processing methods, there are three ways to catch exceptions:

1. Page-level error handling (via Page_Error event)

code is as follows

copy code

protected void Page_Error (object sender, EventArgs e) {     string errormsg = String.Empty;   & nbsp Exception currenterror = Server.GetLastError ();     errormsg + = "System error:<br/>";     errormsg + = "Error Address:" + Request.url + "<br/>";     errormsg + = "error message:" + currenterror.message + "<br/>";     Response.Write (errormsg);     Server.ClearError ()//clear exception (otherwise the global Application_Error event will be thrown) }

2. Application-level (Global.asax) error handling (via Application_Error event)

The code is as follows

Copy Code

protected void Application_Error (object sender, EventArgs e) {     Exception ex = Server.GetLastError (); & nbsp;   Exception IEX = ex. innerexception;     String errormsg = String.Empty;     string particular = String.Empty;     if (IEX!= null)     {         ErrorMsg = IEX. message;         particular = IEX. StackTrace;    }     Else     {         errormsg = ex. message;         particular = ex. StackTrace;    }    //addlog (errormsg, particular);     Server.ClearError ()//Finish cleaning the exception in time }

3. Application Configuration (Web.config)

The code is as follows	Copy Code
<system.web> <!--mode has three values: On,off,remoteonly,defaultredirect url--> with error redirection <customerrors mode= "on" defaultredirect= "errorpage.htm" > <!--statuscode Error status code, redirect error redirect Url--> <error statuscode= "403" redirect= "noaccess.htm"/> <error statuscode= "404" redirect= "filenofound.htm"/> </customErrors> </system.web>

WinForm Application Exception Handling

In WinForm applications, how do you implement global exception handling in addition to the try-catch-finally approach? Because there is no Application_Error event, it can be done by way of a delegate.

The code is as follows

Copy Code

Internal class Threadexceptionhandler { Implementing Error Exception Events public void Application_threadexception (object sender, Threadexceptioneventargs e) { Try { Exit the application if the user clicks "Abort" DialogResult result = Showthreadexceptiondialog (e.exception); if (result = = Dialogresult.abort) { Application.exit (); } } Catch { Try { MessageBox.Show ("Serious error", "Serious error", MessageBoxButtons.OK, Messageboxicon.stop); } Finally { Application.exit (); } } } Private DialogResult Showthreadexceptiondialog (Exception e) { String errormsg = "error message: TT" + e.message + "tt" + e.gettype () + "tt" + e.stacktrace; Return MessageBox.Show (errormsg, "Application Error", Messageboxbuttons.abortretryignore, Messageboxicon.stop); } } Static Class Program { <summary> The main entry point is for the application. </summary> [STAThread] static void Main () { Threadexceptionhandler handler = new Threadexceptionhandler (); Application.ThreadException + = new ThreadExceptionEventHandler (handler. Application_threadexception); Application.enablevisualstyles (); Application.setcompatibletextrenderingdefault (FALSE); Application.Run (New Frmevent ()); } } public partial class Frmevent:form { private void Btnexception_click (object sender, EventArgs e) { throw new InvalidOperationException ("Invalid operation exception!") "); } }