This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
The JarFile constructor takes the name of a local file. This fails, of course, because your jar file is back on the server. You may be able to load the images individually through Class.getResourceAsStream() since the jar is in the classpath (well, ARCHIVE parameter). If that doesn't work you will have to create a URL back to the JAR file and use JarInputStream to load it.