Loading classes dynamically

[fredjones]

I want to be able to modify class at load time, but everything I try doesn't seem to work. I've tried reading the tutorial and doing what it says to, but I don't seem to have any luck. No matter what I do, the original unmodified class is loaded.

Here is what I am trying:

ClassPool pool = ClassPool.getDefault();
String className = "Foo";
CtClass cc = pool.get(className);

cc.defrost();
CtMethod m = new CtMethod(CtClass.voidType, "bar", new CtClass[] {}, cc);
cc.addMethod(m);

Loader cl = new Loader(pool);
cl.delegateLoadingOf(className);
cl.loadClass(className);

Foo foo = new Foo();
Class fooClass = foo.getClass();
Method[] methods = fooClass.getMethods();
for (int i = 0; i < methods.length; i++) {
System.out.println("Method:" + methods.getName());
}

When I run this, "bar" is not one of the methods on Foo. What am I doing wrong???

Thanks,

Fred

[chiba]

> Loader cl = new Loader(pool);
> cl.delegateLoadingOf(className);

Well, this lets the system class loader load
"className" from the disk. Thus the unmodified
class will be loaded.

If the above line is removed,

> cl.loadClass(className);

This call should return the java.lang.Class object
representing the modified class.

> Foo foo = new Foo();

But this statement lets the system class loader load
the unmodified class.

A key thing is that you have to use javassist.Loader
for loading the modified class.