An oldie, but still useful from time to time.

Ever wonder which Jar or directory contains a class you're using in your JEE Web Application? Or which of multiple provider Jar files is the one being used? Or even whether or not a particular class is found at all?

Thanks to this DeveloperWorks article, here's a simple JSP that can be deployed out to any Web Application to answer those questions.

No need to actually include it in your Web App permanently, but easy to deploy manually if you ever need it.