Referencing an optional package in a jar inside an ear

Question

UPDATE: We no longer need this as the third-party will change their shared-library ear to a jar for use on other application servers.
We have no trouble deploying an ear containing a jar as a shared library, and then referencing the classes in it from another application by specifying the appropriate <library-ref> in weblogic-application.xml.
In some installations, that shared library is not required, and indeed may not be present. In that case, the <library-ref> is unresolved, and the application will not deploy. We would like to avoid having two versions of our application - one with the <library-ref> and one without.
If we add the Extension-Name property to the manifest of the jar mentioned above, and deploy the jar (not the ear) as a shared library, our application can reference classes in that jar. The problem is that the library ear (containing the jar) comes from a third party, and we cannot extract out the jar. And the "optional package" mechanism does not appear to work for jars within ears. We've specified the Extension-Name from the library ear ( the one from the library jar is not visible) in the Extension-List of the application. There is no complaint that the optional package is unresolved, but accessing the classes gives ClassNotFoundException.
I did not find any documentation that optional package jars within an ear should be visible to other deployment units, but it seems odd that the third party would package them such that they can only be referenced with the <library-ref> (i.e. on WLS).
http://download.oracle.com/docs/cd/E12840_01/wls/docs103/programming/libraries.html
http://java.sun.com/j2ee/verified/packaging.html
Edited by: mikereiche on Nov 11, 2011 4:34 PM

Answer 1

The JarInputStream class is used to read the contents of a JAR file from any input stream.
InputStream input=getResourceAsStream("/input.xml");
JarInputStream jis
=new JarInputStream(input);