ClassPathHacker.java

package me.chenyi.mm.util;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

import org.apache.log4j.Logger;


public class ClassPathHacker {

	static Logger log = Logger.getLogger(ClassPathHacker.class);

	private static final Class<?>[] parameters = new Class[]{URL.class};

	public static void addFile(String s) throws IOException {
		File f = new File(s);
		addFile(f);
	} 
	public static void addFile(File f) throws IOException {
		addURL(f.toURI().toURL());
	} 
	public static void addURL(URL u) throws IOException {

		URLClassLoader sysloader = (URLClassLoader)ClassLoader.getSystemClassLoader();
		Class<URLClassLoader> sysclass = URLClassLoader.class;

		try {
			Method method = sysclass.getDeclaredMethod("addURL",parameters);
			method.setAccessible(true);
			method.invoke(sysloader,new Object[]{ u });
		} catch (Throwable t) {
			log.error("ClassPathHacker failed: " + t);	    
			throw new IOException("Error, could not add URL to system classloader");
		}
	}
}