On Wed, 17 Jul 2002, Tait E Larson wrote:
> Date: Wed, 17 Jul 2002 10:56:24 -0700
> From: Tait E Larson <[EMAIL PROTECTED]>
> Reply-To: Tomcat Users List <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
> Subject: explicit ordering of jars searched by classloader in web
> application
>
> I've got three third party jar files in the WEB-INF/lib directory of my web
> aplication that contain different versions of the same classes. I need to
> explicitly state the order in which the classloader searches these jars in
> order for my web application to work correctly. Can this be done by
> manipulating the classloader at runtime? Would it be possible to explicitly
> state the jar ordering somewhere in web.xml?
>
If there was such a configuration option (and there's not) it would be
defined in the Servlet Specification
<http://java.sun.com/products/servlet/download.html>.
The only promise you get is that classes in "WEB-INF/classes" will be
loaded in preference to classes from JAR files in "WEB-INF/lib". For the
individual JAR files in "WEB-INF/lib" directory, that is totaly up to the
container (and may not even be in the container's control if you run your
webapp from an open directory the way that Tomcat lets you do it).
IMHO, application designs that rely on this kind of thing are incredibly
fragile, because they rely on this sort of an internal detail. I'd look
for libraries that let you configure which implementation of a particular
API you want (for example, the way that JAXP APIs let you configure which
parser implementation to use) instead.
> Thanks,
>
> Tait
Craig
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