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From "Kevin Sutter (JIRA)" <j...@apache.org>
Subject [jira] Created: (OPENJPA-133) Can't find non-public callback methods with superclass or interface parameters
Date Wed, 07 Feb 2007 22:54:05 GMT
Can't find non-public callback methods with superclass or interface parameters
------------------------------------------------------------------------------

                 Key: OPENJPA-133
                 URL: https://issues.apache.org/jira/browse/OPENJPA-133
             Project: OpenJPA
          Issue Type: Bug
          Components: jpa
            Reporter: Kevin Sutter
         Assigned To: Kevin Sutter


Using xml to define my listener callback methods (doesn't make any difference whether we're
using MappedSuperclass or Entity):

	<mapped-superclass class="com.ibm.ws.persistence.tests.callbacks.CallbackSuperclass">
			<entity-listeners>
				<entity-listener class="com.ibm.ws.persistence.tests.callbacks.CallbackListener">
					<!--
					<pre-persist  method-name="prePersistXML" />
					-->
					<post-persist method-name="postPersistXML" />
					<!--
					<pre-remove   method-name="preRemove" />
					<post-remove  method-name="postRemove" />
					<pre-update   method-name="preUpdate" />
					<post-update  method-name="postUpdate" />
					<post-load    method-name="postLoad" />
					-->
				</entity-listener>
			</entity-listeners>
	</mapped-superclass>

My Entity heirarchy is defined as follows:

public interface CallbackMarker { }

@MappedSuperclass
public class CallbackSuperclass implements CallbackMarker { .. }

@Entity
public class CallbackEntity extends CallbackSuperclass { .. }

My listener method is defined as follows:

public class CallbackListener {
:
    private void postPersistXML(CallbackMarker cbm) {
        System.out.println("PostPersist (ListenerXML) on CallbackMarker: " + cbm);
        ((CallbackEntity)cbm).postSuccessful = true;
    }
:
}

I'm probably clouding the issue with all of these details, but the real problem is that we're
not properly finding the postPersistXML(CallbackMarker cbm) method.  When I run the example,
I am getting the following exception.  The original
call stack is huge, so I will just include the "caused by":

Caused by: java.lang.NoSuchMethodException: com.ibm.ws.persistence.tests.callbacks.CallbackListener.postPersistXML(com.ibm.ws.persistence.tests.callbacks.CallbackSuperclass)
	at java.lang.Class.throwNoSuchMethodException(Class.java:271)
	at java.lang.Class.getMethod(Class.java:748)
	at org.apache.openjpa.event.MethodLifecycleCallbacks.getMethod(MethodLifecycleCallbacks.java:123)

Digging through the problem, I am finding that we're not properly reflecting on the Class
to find the appropriate Method.  First, we
do a getMethods(), which only returns the public methods.  Of course, nothing matches up,
so we end up in the catch {} block.  Here,
we attempt a getDeclaredMethod() passing in the specific type for the argument.  This doesn't
work in this case since the specific
type (CallbackSuperclass) isn't on the Method signature (the interface CallbackMarker is).
 Also, calling getDeclaredMethod only looks in the specific Class and does not go up the heirarchy
(like getMethods() does).  So, we have a couple of problems with this
method.

My proposed change is to use the getDeclaredMethods() invocation and manually go up the heirarchy
(if necessary).  If we go all the way up the tree without finding the method, then we throw
the exception.  This seems to clear up the processing and makes the code
more readable (no try/catch is required).  You could argue that this approach might take more
processing since we might have to get the Superclass and make additional getDeclaredMethods()
invocations.  But, my guess is that most of the methods being requested will be on the base
class and no additional invocations will be necessary.

FYI, this problem only exists with the XML configuration since the annotated version doesn't
do this parameter checking.  Annotated callback methods just register the method and assume
that it will work.  If it doesn't, then we get a runtime exception with IllegalArgumentException.
 Whether we should do this type checking for the annotated callbacks is a topic for a separate
JIRA report...

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