A classloader loads the jars so, the files in a jar are accessed from the classloader. Use the method classloader.getResourceAsStream(
String), or URL classloader.getResource(String).
To make sure you are using the same classloader as the one that loaded the jar,
you should get the classloader from a object who's class is in the jar.
Classloader classloader = someObject.getClass().getClassloader();
If you want to access the jar with jar apis, you can get a url then use jar api's.