ClassLoader : brutal JAR insertion at runtime

I didn't remember where I found this, but I'd like to thank a lot the person who had invented it...
I'd never had figured such a thing by myself, or maybe after long and desperate nights of headache, as a last chance...
But the fact is : it works ! And it works fine !

The idea is to insert new URLs in the system classloader, to allow some JARs to be part of it after startup... for me, it's was a manner to expose a kind of pluggable component feature : you just drop a JAR in a specific directory, and without modifying a single line of startup script or whatever, your jar comes to life automaticaly in the app.

And now the beast, using a bit of reflective API, reaaaaally messy :

    private static final Class[] parameters = new Class[]{URL.class};
    
    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");
        }
    }