ClassPathHacker.java

package net.sf.thingamablog;

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


public class ClassPathHacker
{
    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.toURL());
    }

    public static void addURL(URL u) throws IOException
    {

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

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

    }

}