Miscellany

import java.lang.reflect.Method;
import java.lang.Class;
import java.lang.reflect.Proxy;
import java.util.*;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;


interface I{
    public void hello();
}
class A implements I{
    public void hello(){
	System.out.println("hello");
    }
}

interface B{
    public void call_hello(I i);
    public void foo();
}

class BImpl implements B{
    public void call_hello(I i){
	i.hello();
    }
    public void foo(){
	System.out.println("foo");
    }

}

class BProxy implements InvocationHandler {
    private B first;
    private B second;

    Set send_to_first = new HashSet(Arrays.asList(new String[]{ "foo","bar"}));
    Set send_to_second = new HashSet(Arrays.asList(new String[]{ "zork","foobar"}));
    Set send_to_both = new HashSet(Arrays.asList(new String[]{ "something"}));
    
    public static Object newInstance(B b) {
	return java.lang.reflect.Proxy.newProxyInstance(
							B.class.getClassLoader(),
							new Class[] { B.class },
							new BProxy(b));
    }

    public BProxy(B b) {
	this.first = b;
	this.second = new BImpl();
    }

    public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
        Object result;
	try {
	    String methodName = m.getName();

	    if (send_to_first.contains(methodName)){
		return m.invoke(first, args);
	    } else if (send_to_second.contains(methodName)){
		return m.invoke(second, args);
	    } else {
		return m.invoke(this, args);
	    }
        } catch (InvocationTargetException e) {
	    throw e.getTargetException();
        }// catch (Exception e) {
	 //   throw new RuntimeException("unexpected invocation exception: " +
	//			       e.getMessage());
	//}
    }
}


public class testCase{
    public static void main(String[] args) {
	try{
	    B b = new BImpl();
	    A a = new A();
	    b.call_hello(a);

	    B proxy = (B) BProxy.newInstance(b);
	    proxy.foo();
	    proxy.call_hello(a);
	    
	} catch (Exception e){
	    e.printStackTrace();
	}
    }
}