Questions on Dependencies
I have a few questions about dependencies. I've simplified the problem below considerably, so understand that I can't simply restructure everything.
I have a problem where a Web-App's MANIFEST-MF references <project1>.jar, which is contained in the EAR file.
That was fine until I added code to <project1>.jar that was dependent on <project2.jar>.
<project2>.jar exists in the Web-Apps WEB-INF/lib directory.
1) The Web App calls code in project1.jar, which calls code in project2.jar. At that point I get a classcastexception.
Why is it that it doesn't look in the WEB-INF/lib directory jars for the class? Is it because the project 1 code exists outside the WEB-INF directory?
2) I can add project2.jar to the ear and reference it in the MANIFEST.MF. If I do this, why does the class cast exception go away?
[881 byte] By [
rayne5446a] at [2007-11-26 12:58:16]
# 1
If the two projects aren't in the same EAR then they are loaded with different, non-related classloaders, which isn't allowed.
In Tomcat, you can move common code into the $Catalina_Home/shared/lib/ directory which has a Classloader that is the parent of all the webapps.
Or you can put them in the same EAR.
# 4
I think I've actually tracked the problem down to the application class loader. The application class loader on the server will load project1.jar (dependency jar listed in a manifest), but the web module class loader will load project2.jar (web-inf/lib).
From what I've read, a class loaded by a class loader cannot reference any classes held by a child class loader. Since the web module class loader is a child of application class loader, project2.jar is not visible.
Therefore, I can specify project2.jar in the MANIFEST.MF, which will cause it to be loaded by the application class loader and it will become visible.
