Recipe13.7.Executing Advice Only After an Exception Has Been Raised in a Join Point

Recipe 13.7. Executing Advice Only After an Exception Has Been Raised in a Join Point

Problem

You want advice to execute after a specific join point only if that join point raised an exception.

Solution

Use the after( ) tHRowing or after() throwing(<ExceptionType> <Identifier>) types of advice

Discussion

Example 13-8 shows how to specify that advice should be executed if the call to the void MyClass.foo(int) method returns with an exception.

Example 13-8. Executing advice after a method call if that call raises an exception

public aspect AfterThrowingAdviceRecipe  {    /*    Specifies calling advice whenever a method    matching the following rules gets called:        Class Name: MyClass    Method Name: foo    Method Return Type: void    Method Parameters: an int followed by a String    */    pointcut callPointCut( ) : call(void MyClass.foo(int));    // Advice declaration    after( ) throwing : callPointCut( )       && !within(AfterThrowingAdviceRecipe +)    {       System.out.println(          "------------------- Aspect Advice Logic --------------------");       System.out.println(          "Source Location: "             + thisJoinPoint.getStaticPart( ).getSourceLocation( ));       System.out.println(          "------------------------------------------------------------");    } }

The after( ) throwing advice type completes the picture for applying advice to be executed after a join point returns. In this case, the advice should be executed when an exception has occurred. This gives the developer the capability to handle exceptional circumstances after a join point has been executed.

See Also

The call(Signature) pointcut is described in Recipe 4.1; the handler(TypePattern) pointcut is shown in more detail in Recipe 5.1; the within(TypePattern) pointcut is described in Recipe 9.1; the thisJoinPoint variable and the context it encapsulates is examined in Recipe 13.2; the after( ) and after( ) returning advice types are described in Recipes Recipe 13.5 and Recipe 13.6 respectively.