本文记录对java JDK中动态代理的理解。

动态代理的类图如下：

package com.hef.basepro.dynamicproxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Random;

/**
 * ProxyTest
 */
public class ProxyTest {
    public static void main(String[] args) {
        Object[] elements = new Object[1000];

        // fill elements with proxies for the integers 1... 1000
        for (int i = 0; i < elements.length; i++) {
            Integer value = i + 1;
            InvocationHandler handler = new TraceHandler(value);
            Object proxy = Proxy.newProxyInstance(null, new Class[]{Comparable.class}, handler);
            elements[i] = proxy;
        }

        // construct a random integer
        Integer key = new Random().nextInt(elements.length) + 1;

        // search for the key 
        int result = Arrays.binarySearch(elements, key);

        // print match if found
        if(result >= 0) System.out.println(elements[result]);
    }
}

class TraceHandler implements InvocationHandler {

    private Object target;

    public TraceHandler(Object t){
        target = t;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        // print implicit argument
        System.out.print(target);
        // print method name
        System.out.print("." + method.getName() + "(");
        // print explicit arguemnt
        if (args!=null){
            for (int i = 0; i < args.length; i++) {
                System.out.print(args[i]);
                if(i<args.length-1) System.out.print(", ");
            }
        }
        System.out.println(")");
        // invoke actual method
        return method.invoke(target, args);
    }
    
}