1.代码

package com.che.carcheck.ui.helper;

import com.che.carcheck.support.util.LogUtil;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
 * 代理模式学习
 *
 * 作者：余天然 on 16/5/6 下午2:30
 */
public class ProxyStudy {

    //使用场景
    public static void main() {
        //被代理类
        UserImpl impl = new UserImpl("小明");
        impl.login();
        impl.updateInfo();

        //静态代理
        LogUtil.print("静态代理:开始");
        UserStaticProxy staticProxy = new UserStaticProxy(impl);
        staticProxy.login();
        staticProxy.updateInfo();

        //动态代理
        LogUtil.print("动态代理:开始");
        UserDynamicProxyFactory factory = new UserDynamicProxyFactory();
        User dynamicProxy = (User) factory.createProxy(impl);
        dynamicProxy.login();
        dynamicProxy.updateInfo();
    }

    //接口
    public interface User {
        void login();

        void updateInfo();
    }

    //被代理类
    public static class UserImpl implements User {
        private String name;

        public UserImpl(String name) {
            this.name = name;
        }

        @Override
        public void login() {
            LogUtil.print(this.name + "登录……");

        }

        @Override
        public void updateInfo() {
            LogUtil.print(this.name + "更新信息……");
        }

    }

    //静态代理
    public static class UserStaticProxy implements User {
        private UserImpl countImpl;

        public UserStaticProxy(UserImpl countImpl) {
            this.countImpl = countImpl;
        }

        @Override
        public void login() {
            doBefore();
            countImpl.login();
        }

        @Override
        public void updateInfo() {
            doBefore();
            countImpl.updateInfo();
            doAfter();
        }

        private void doBefore() {
            LogUtil.print("静态代理:前置动作……");
        }

        private void doAfter() {
            LogUtil.print("静态代理:后置动作……");
        }

    }

    //JDK动态代理
    public static class UserDynamicProxyFactory implements InvocationHandler {
        private Object target;

        //绑定委托对象并返回一个代理类
        public Object createProxy(Object target) {
            this.target = target;
            //取得代理对象
            return Proxy.newProxyInstance(target.getClass().getClassLoader(),
                    target.getClass().getInterfaces(), this);//要绑定接口(这是一个缺陷，cglib弥补了这一缺陷)
        }

        //改变方法的调用逻辑
        @Override
        public Object invoke(Object proxy, Method method, Object[] args)
                throws Throwable {
            Object result = null;
            //执行方法
            if (method.getName().equals("login")) {
                doBefore();
                result = method.invoke(target, args);
            }
            if (method.getName().equals("updateInfo")) {
                doBefore();
                result = method.invoke(target, args);
                doAfter();
            }
            return result;
        }

        private void doBefore() {
            LogUtil.print("动态代理:前置动作……");
        }

        private void doAfter() {
            LogUtil.print("动态代理:后置动作……");
        }

    }

}

2.日志