Exporting to Runnable jar with extra native code libraries in eclipse

Add a script containing something like that:

#!/bin/bash
java -Djava.library.path=project_lib/native/ -jar project_lib/jri.jar

I export some java projects that way.

This is relatively hard to implement. The solutions I have seen involve extracting the native libraries in the JAR to an OS temp directory and then loading it. I would go for an integrated solution for that. One Jar and Java Class Loader support it, and on the second page you will find links to similar tools.