new JarFile(String name)
import java.io.FileOutputStream; import java.io.OutputStream; import java.util.jar.JarFile; import java.util.jar.Pack200; public class Main { public static void main(String[] args) throws Exception { OutputStream out = null; JarFile f = new JarFile(args[0]); Pack200.Packer packer = Pack200.newPacker(); out = new FileOutputStream(args[0] + ".pack"); packer.pack(f, out); out.close(); } }