Re: Custom class loader

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 30 Sep 2006 15:28:21 -0400

Message-ID:

<nzzTg.1089$2g4.131@dukeread09>

spaceman wrote:

Arne Vajh?j wrote:

WEB-INF/lib ? No !

Let me be more specific. The problem I have is that both a.jar and
b.jar have some classes which are the same ( duplicated ). If I put
them toghether in WEB-INF/lib the classloader gets messed up due to the
duplicate classes.

Yes.

You need two custom classloaders one for each jar and the jars
must not ne in path for parent classloaders.

URLClassLoader cl = new URLClassLoader(urlofjar);
X o = (X)Class.forName(clsnam, true, cl).newInstance();

This seem to be a good possibility however as there is no entry point
and there are a lot of classes, I'm not sure how I can control the
creation of each class and use my own class loader.
Also how can I have the web server load the jars at some point if they
are not in web-inf/lib?

The Class.forName code above explicit specify classloader.

The URL for the classloader can be any URL including file
URL's.

Note that the deployment of you app will become a bit tricky, but
that is how it has to be.

Arne