课程名：Windows应用程序开发入门到精通七：优化.NET异常处理
1.多个catch块的情况时会过滤异常，先截获具体的异常，再截获一般的异常，并且这是从编译器的层次就支持的。
2.应该从系统异常(System.ApplicationException)派生自己的具体异常，从而为特定的应用程序提供更好的支持。
3.异常处理技术：1）记录异常：在文件中记录异常；在数据库中记录；在Eventlog中记录。2）发email等信息来通知异常。总之，要以用户友好的方式通知异常的发生。
4.使用Application对象中的ThreadException属性来设置一个delegate来捕获所有未处理的主线程中出现的异常，但并不能处理你自己创建的工作进程中出现的异常。
public static void Main(string[] args)
{
Application.ThreadException += new
ThreadExceptionEventHandler(
MainUIThreadExceptionHandler);
Demo6();
System.Windows.Forms.Application.Run(
new NorthwindMDIMain());
}
public static void MainUIThreadExceptionHandler(
Exception e)
{
MainUIThreadExceptionHandler(null, new System.Threading.
ThreadExceptionEventArgs(e));
}
public static void MainUIThreadExceptionHandler(object
sender, ThreadExceptionEventArgs t)
{
ExceptionManager.Publish(t.Exception);
//Tell the user a boo-boo occurred
MessageBox.Show(
"Northwind Orders has encountered the following "
+ " problem:" + (char)13
+ (char)13 + t.Exception.Message
+ (char)13 + (char)13
+ "Please contact your administrator or the "
+ "Northwind Help desk at "
+ (char)13 + (char)13 +"1-855-555-5555."
+ (char)13 + (char)13
+ "We apologize for the inconvenience."
, "Northwind Orders Encountered a Problem"
, MessageBoxButtons.OK
, MessageBoxIcon.Error
, MessageBoxDefaultButton.Button1
, MessageBoxOptions.ServiceNotification);
}
5，必须考虑在工作线程中出现的异常，在线程的入口使用try-catch,并且使用delegate等方式将异常通知给主线程，此外，线程之间要访问对方的界面成员时，应该通过BeginInvoke（）方法来进行。
public delegate void DoneDelegate(bool Stopped);
public delegate void
WorkerThreadExceptionHandlerDelegate(Exception e);
void WorkerThreadExceptionHandler(Exception e)
{
UpdateProgress();
SetStatusText("Problem Encountered");
this.Text = "Customers";
btnSave.Text = "Save";
btnClose.Enabled = true;
//Call the global exception handler
MainClass.MainUIThreadExceptionHandler(
this, new System.Threading.
ThreadExceptionEventArgs(e));
}
private void btnSave_Click(object sender, System.EventArgs e)
{
try
{
if(true==btnSave.Enabled)
{
this.Text = "Customers (Saving)";
btnSave.Enabled=false;
btnClose.Enabled=false;
System.Threading.Thread t =
new System.Threading.Thread(
new System.Threading.ThreadStart(
SaveCustomer));
t.Start();
}
else
{
isCanceled = true;
btnSave.Enabled = true;
}
}
catch(NotSupportedException exception)
{
MessageBox.Show("Code not done yet "
+ exception.Message
);
}
catch(Exception exception)
{
//Tell the user a boo-boo occurred
MainClass.MainUIThreadExceptionHandler(this
,new System.Threading.
ThreadExceptionEventArgs(exception));
MessageBox.Show(
"Northwind Orders has encountered a problem. "
+ "Please contact your administrator or the "
+ "Northwind Help desk at "
+ (char)13 + (char)13 +"1-855-555-5555."
+ (char)13 + (char)13
+ "We apologize for the inconvenience."
, "Northwind Orders Encountered a Problem"
, MessageBoxButtons.OK
, MessageBoxIcon.Error);
}
finally
{
this.Cursor=Cursors.Default;
}
}
private void SaveCustomer()
{
try
{
SetStatusText(
"Saving record on a background thread");
//TODO: Add code to save the customer record
this.BindingContext[dsCustomers,"Customers"].
EndCurrentEdit();
dsCustomers objDataSetChanges = ((dsCustomers)
(dsCustomers.GetChanges()));
if(null!=objDataSetChanges)
new NorthwindDataAccess().UpdateCustomers(
objDataSetChanges);
isCanceled = false;
DoneDelegate delDone = new DoneDelegate(Done);
delDone.BeginInvoke(isCanceled, null, null);
}
catch(Exception e)
{
new WorkerThreadExceptionHandlerDelegate(
WorkerThreadExceptionHandler).BeginInvoke(e
,null
,null);
}
}
private void Done (bool Stopped)
{
UpdateProgress();
this.Text = "Customers";
btnSave.Enabled=true;
btnClose.Enabled=true;
if(Stopped)
{
MessageBox.Show("Save Stopped"
, "Stopped"
, MessageBoxButtons.OK
, MessageBoxIcon.Warning);
SetStatusText("Save Stopped");
}
else
{
MessageBox.Show("Save Done"
, "Done"
, MessageBoxButtons.OK
, MessageBoxIcon.Information);
SetStatusText("Save Done");
}
}
6，在构造函数中不要加try-catch，因为这会把异常再抛给外部方法，还不如不处理，直接抛给外部好了。
7，异常处理程序块采用的是publisher/subscriber设计模式，在工程中添加对它的引用，并引入名称空间Microsoft.ApplicationBlocks.ExceptionManagement就可以使用ExceptionManager.Publish()来进行异常的发布。在app.config中可以对异常管理进行启/停，还可以添加自己的异常处理模块。
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="exceptionManagement"
type="Microsoft.ApplicationBlocks.ExceptionManagement.ExceptionManagerSectionHandler,Microsoft.ApplicationBlocks.ExceptionManagement" />
</configSections>
<exceptionManagement mode="on">
<publisher mode="on" assembly="Microsoft.ApplicationBlocks.ExceptionManagement"
type="Microsoft.ApplicationBlocks.ExceptionManagement.DefaultPublisher"
logname="Northwind Exceptions Log"
applicationname="Northwind Traders Orders" />
</exceptionManagement>
</configuration>
public static void MainUIThreadExceptionHandler(object
sender, ThreadExceptionEventArgs t)
{
ExceptionManager.Publish(t.Exception);
//Tell the user a boo-boo occurred
MessageBox.Show(
"Northwind Orders has encountered the following "
+ " problem:" + (char)13
+ (char)13 + t.Exception.Message
+ (char)13 + (char)13
+ "Please contact your administrator or the "
+ "Northwind Help desk at "
+ (char)13 + (char)13 +"1-855-555-5555."
+ (char)13 + (char)13
+ "We apologize for the inconvenience."
, "Northwind Orders Encountered a Problem"
, MessageBoxButtons.OK
, MessageBoxIcon.Error
, MessageBoxDefaultButton.Button1
, MessageBoxOptions.ServiceNotification);
}
可以在“事件查看器”中看到异常已经发布进来了：
本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2006/10/28/543145.html，如需转载请自行联系原作者
