Java 類型信息 動態綁定

import java.lang.reflect.*;
import java.util.HashMap;

interface Interface {
    void say();
    void sayMore(int i);
}

interface Interface2 {
    void hello();
}

class Real implements Interface, Interface2 {
    public void say() {System.out.println("fuck u"); }
    public void sayMore(int i) {System.out.println(i);}
    public void hello() {System.out.println("hello");}
}

class DynamicProxyHandler implements InvocationHandler {
    private Object proxied;
    private HashMap<Method,Integer> count;
    DynamicProxyHandler(Object proxied) {
        this.proxied = proxied;
        this.count = new HashMap<>();
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //System.out.println(proxy);                            //這裏StackOverflow，應當是因爲toString中調用了invoke
        if (count.containsKey(method)==false)
            count.put(method,0);
        count.replace(method,count.get(method)+1);
        System.out.println(count);
        return method.invoke(proxied,args);
    }
}

public class Ans {
    public static void consumer(Interface iface,int i) {
        iface.say();
        iface.sayMore(i);
    }
    public static void consumer(Interface2 iface) {
        iface.hello();
    }

    public static void main(String[] args) {
        Real obj = new Real();
        //consumer(obj,1);
        Interface obj2 = (Interface)Proxy.newProxyInstance(
            Interface.class.getClassLoader(),
            new Class[] {Interface.class,Interface2.class},
            new DynamicProxyHandler(obj)
        );
        System.out.println(Interface.class.getClassLoader());
        consumer(obj2,2);
        consumer(obj2,2);
        consumer((Interface2)obj2);
    }
}

這個和加載器有關係，詳情見加載器