RunJar.java

import java.util.*;
import java.util.jar.*;
import java.net.*;
import java.lang.reflect.*;

public class RunJar {
	
	public static void main(String[] args) {
		try {
			String jarfile = args[0];
			args = java.util.Arrays.copyOfRange(args, 1, args.length);
			JarFile jar = new JarFile(jarfile);
			Manifest mf = jar.getManifest();
			String mainClass = mf.getMainAttributes().getValue("Main-Class");
			URLClassLoader ucl = new URLClassLoader(
					new URL[] { new URL("file:///" + jarfile) },
					new Object().getClass().getClassLoader());
			Thread.currentThread().setContextClassLoader(ucl);
			Class klass = ucl.loadClass(mainClass);
			Method main = klass.getMethod("main", String[].class);
			try {
				main.invoke(null, new Object[] { args });
			} catch (InvocationTargetException ex) {
				throw ex.getCause();
			}
		} catch (Throwable ex) {
			ex.printStackTrace();
		}
	}
	
}