This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Read from the JarInputStream directly. Everytime you call getNextJarEntry it positions itself to the next entry, and you can read its contents until all is read (read returns -1). Then you call getNextJarEntry again and read all again.