Doing a quick read of your code, I think the problem is that you're
using "call(...)" in the pointcut definition, which won't work with
the reflection API. The "call" means aspectj will try to advise the
code that is calling the method, but that's happening inside Java's
reflection API, which aspectj won't touch. Even if aspectj could
advise JDK code, it still wouldn't know to advise the reflection API
in this situation, because the method is referred to by a string name,
rather than by the actual class and method itself.
Instead, I think if you use "execute(...)" in your pointcut, it will
work. In this case, aspectj will advise your code - the method whose
exception you are trying to catch.
I hope this works!
dean
On Dec 14, 2007, at 1:02 PM, Herve Attia wrote:
Hello,
First of all, I'm a newbie with AOP. I'm learning aspectJ framework
I'm testing the "exception introduction pattern" example ( ch11.4.2)
from the "AspectJ in action" book.
The sample works great until you invoke the caller object using
reflection API. The PreserveCheckedException advice code (described
below ) is NOT invoked anymore.
Once the the ConcernAspect around advice throws the
ConcernRuntimeException, this exception is directly wrapped within
an java.lang.reflect.InvocationTargetException .
The issue is not related to the sample but to some side effect
between reflection framework exception handling and AspectJ weaving.
How can we make the PreserveBusinessException advice code invoked in
this special case ?
I attached the source code.
Thanks for your advice! ;)
-herve
/////////////////// test program ////////////////////////////////
import java.lang.reflect.Method;
public class TestException {
public static void main(String[] args) {
BusinessClass bc = new BusinessClass();
/*
//works fine!. PreserveBusinessException Advice code is invoked
bc.businessMethod1();
try {
bc.businessMethod2();
} catch (Exception ex) {
// Do something...
// Log it, execute recovery mechanism, etc.
System.out.println ("Caught:" + ex);
}
*/
try {
//PreserveBusinessException Advice code is not invoked
Class cl=Class.forName ("BusinessClass");
Method method = cl.getMethod("businessMethod2", null);
method.invoke(bc, null);
} catch (Exception ex) {
// Do something...
// Log it, execute recovery mechanism, etc.
System.out.println("Caught:" + ex);
}
}
}
//////////////////////// abstract aspect
class ///////////////////////
public abstract aspect ConcernAspect {
abstract pointcut operations();
Object around() : operations() {
try {
return proceed();
}
catch (Throwable ex) {
// do something
throw new ConcernRuntimeException(ex);
}
}
}
//////////////////////// PreserveBusinessException : aspect which
captures all the methods throwing a ConcernRuntimeException and
throws the cause instead ///////////////////////
public aspect PreserveBusinessException {
declare precedence: PreserveBusinessException, ConcernAspect+;
after() throwing(ConcernRuntimeException ex) throws
BusinessException: call(* *.*(..) throws BusinessException) {
Throwable cause = ex.getCause();
System.out.println("PreserveBusinessException advice called:" +
ex);
if (cause instanceof BusinessException) {
throw (BusinessException)cause;
}
throw ex;
}
}
//////////////////////// business concrete aspect implementation
class ///////////////////////
public aspect BusinessConcernAspect extends ConcernAspect {
pointcut operations() : execution(* BusinessClass.business*());
}
//////////////////////// businessClass ///////////////////////
public class BusinessClass {
public void businessMethod2() throws BusinessException,
IllegalStateException{
// business logic...
throw new BusinessException();
}
}
//////////////////////// BusinessException
class ///////////////////////
public class BusinessException extends Exception {
}
//////////////////////// ConcernRuntimeException
class ///////////////////////
public class ConcernRuntimeException extends RuntimeException {
public ConcernRuntimeException(Throwable cause) {
super(cause);
}
}
<testException.rar>_______________________________________________
aspectj-users mailing list
[email protected]
https://dev.eclipse.org/mailman/listinfo/aspectj-users
Dean Wampler, Ph.D.
dean at objectmentor.com
http://www.objectmentor.com
See also:
http://www.aspectprogramming.com AOP advocacy site
http://aquarium.rubyforge.org AOP for Ruby
http://www.contract4j.org Design by Contract for Java5
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