J2EE Java Blueprints package/directory structure: best practice for common code?

I am working on several Java J2EE web applications using struts/
tomcat, and I have common Java code that I want to share between
multiple J2EE web apps.

Question: Is there a best practice for where common Java code should
be placed in the J2EE Java BluePrints package/directory structure?

http://java.sun.com/reference/blueprints/

Should this code be placed into a JAR file?

Or, is it OK to include the common source files as part of the build
for each app?

Would it make any sense to place the code under apps?

How about placing it in the root directory under src/java/com?

I'm just looking for ideas.

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