I do not think it is possible to find the the best way
for this stuff, but we expected hibernate (and cglib)
classes will be in the same or in the parent
classloader (asumption is based on j2ee container
class loading stuff). It must be better to use this
asumption, it has more chances to be maintained.
Well, unfortunately not.
Our classloading should try to do as ReflectHelper does.
look in ctxthread first and then in the class own classloader.
that is the right way to do it in J2EE, not the other way around.
As I understand it cglib in this case only look in its own classloader.
-max
--- "Ivan S. Dubrov" <[EMAIL PROTECTED]> wrote:
>
>cant see your attachement (at netcafe ,), but im
quite sure this is not the right solution to this
*eclipse* problem ,)
>
>And I cant recall having this issue when installing
own classloader.
>
>you should go to eclipse and look for the bug
talking about buddy classloading which can handle
>this via eclipse classloader madness.
>
>max
No. This is not bug. I understand all Eclipse
classloaders "madness". This is feature :)
I'll try to describe it again. I do not want make my
entity classes "see" hibernate jar's (because I want
to support pluggable persistence layers, for example
via Hibernate or via JDBC, etc). Saying it another
way, classloader of mine entity classes do not see
hibernate classes - I just _want_ it to be this way.
But when Hibernate generates proxy factory, it uses
default Enhancer "create" method, look at the
snippet:
return (Factory) Enhancer.create(
(interfaces.length==1) ?
persistentClass : null,
interfaces,
NULL_METHOD_INTERCEPTOR
);
If you look into the Enhancer source code, you'll
see that if classloader was not set explicitly it
uses superclass (the class that will be used as
superclass for generated proxy) classloader. And the
superclass in this case is mine entity class. So
CGLib tries to generate proxy using my entity
classloader. But interfaces array contains
HibernateProxy interface, and this is class from
Hibernate jar, so it is not seen from my entity
classloader (this is by desire). So CGLib fails to
generate proxy (with an exception of
ClassNotFoundException).
That's the problem. I've solved it very simple - in
case of CodeGenerationException thrown from the
Enhancer.create(), I call Enhancer again, but with
classloader explicitly set to the
Thread.currentThread().getContextClassLoader(). I
think this is OK, since ReflectHelper already uses
thread context classloader to load entities (that's
why my entity is loaded by the Hibernate
successfully, despite the fact that it is in the
different classloader than Hibernate itself).
I think the current behaviour of Hibernate is
inconsistent - it can load entity classes from
unrelated classloader (using the thread context
classloader), but it fails to generate proxies for
them (since it requires classloader of entity
classes to see HibernateProxy class).
The better way, of course, will be the ability to
pass Hibernate classloader that will be used both
for loading entity and generating proxy for it.
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