eclipselink PersistenceUnitLoadingEception in executable JAR

Question

I am developing a stand-alone java application which uses eclipselink. It is all fine when I execute the app from eclipse IDE. But I\'ve exported an executable JAR file, and

Answer 1

Some background info

As the link you've provided says, EclipseLink doesn't seem to support loading persistence.xml when the EclipseLink jar is embedded in your app's jar.

As I understand it, standard non-customized Java doesn't support runnable jars that load classes from embedded jars. The runnable jar that Eclipse creates is able to overcome that limitation by adding a custom classloader (org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader) to your app's jar. The custom classloader apparently is where EclipseLink runs into this issue.

With that said, in Eclipse Helios, I've found it more manageable to "Copy required libraries into a sub-folder next to the generated JAR" rather than to "Extract required libraries into generated JAR."

Choosing the copy option keeps the eclipselink jar intact, as opposed to Eclipse extracting the various .class files and cluttering your application's jar. True, your app will no longer be distributable as a single jar, but from a manageability standpoint, this seems better than the extract-libraries option.