异常处理弹簧

Question

We are converting our app from Struts 1.2 to Springs 3.0. So we are making changes in exception handling done in our Struts 2 code.

As per my undestanding this is how we need to do.

1. @ExceptionHandler can be used only in the Controller layer of Springs.
2. We can use AOP for handling Unchecked Exceptions.
3. Checked Exceptions in Struts will remain as it is and can be converted to unchecked exceptions

Now I have following questions.

1. Whats the benefit of using AOP for handling unchecked exceptions except that the unchecked exception need not be handelled in my code?
2. Whats the benefit of converting checked exception to Unchecked exception?
3. Should I go ahead and convert my checked exceptions in struts to unchecked exception and us the AOP?
4. What could be the better approach to handle Exceptions in Spring 3.0 ?

Answer 1

Have a look at Spring's facilities for exception handling:

http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/mvc.html#mvc-exceptionhandlers

The idea is similar to your approach for using AOP, but requires a lot less configuration. Essentially, you register a handler for any kind of unchecked exception your code throws. This lets you test your code by asserting whether or not the exception was thrown, and decoupling that logic from handling and recovering from the exception.

Answer 2

The @ExceptionHandler value can be set to an array of Exception types. If an exception is thrown matches one of the types in the list, then the method annotated with the matching @ExceptionHandler will be invoked. If the annotation value is not set then the exception types listed as method arguments are used.

Spring uses AOP internally which you need not work on. It gives you all the bolt and nuts code.