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Message-ID: <903A7281CDB7D4118A5000500450BB08382D9A@samoa.sitewaerts>
From: Daniel Hoppe <hoppe@sitewaerts.de>
To: "'ant-dev@jakarta.apache.org'" <ant-dev@jakarta.apache.org>
Subject: Ant Classloader - Context Classloader
Date: Sun, 22 Jul 2001 22:07:51 +0200
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Hi all,

I just wrote my first custom task (big compliment to the Ant architects =
- it
was really easy and straightforward!) and have some questions regarding
classloading.

My task calls a class ("foo.class") which connects to an application =
server
and performs some bulk operations. Therefore I need to perform a JNDI =
lookup
to the server within foo. My task class is in the Ant lib directory and
included by a taskdef. If I include foo into the jar I have the =
following
situation:

- foo is in the ant library classpath / system classpath
- The JNDI InitialContextfactory of my application server needs to be =
in the
same classpath as well. If it's in a nested classpath element it  won't =
be
found from the classloader which loaded foo as that classloader is =
higher in
the hierarchy
- Therefore I'd need to put all application server classes into the =
system
classpath what I don't really like.

If I don't include foo into the jar but make my task use a nested =
classpath
attribute, I cannot directly reference foo as it is not in the system
classpath. I need to perform some heavy reflection to create an =
instance.
This works fine, but I wonder if there is a nicer approach.

If foo is loaded from the nested classpath element, further classloads =
from
within this class are performed by the Ant classloader which is to be
expected. What I don't understand is why the Ant classloader is not the
context classloader as well. Although I have my application server =
classes
in the nested classpath element, I have to set the context classloader
manually by calling

Thread.currentThread().setContextClassLoader(this.getClass().getClassLoa=
der(
));

before I create the InitialContext within foo.

I did not find anything about this point in the mail-archive and I'm
wondering if this is an intended behaviour. It would be nice if someone
could put some light onto this.

Thanks in advance,

Daniel




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