设计模式

设计模式总览

菜鸟教程-设计模式简介

代理模式

https://www.bilibili.com/video/BV1D7411i7mT?p=238

public class TestProxy {
    public static void main(String[] args) {
        UserDao userDao = new UserDao();
        UserDaoProxy userDaoProxy = new UserDaoProxy(userDao);
        userDaoProxy.add();
    }
    public interface Dao {
        void add();
    }
    //被代理类
    public static class UserDao implements Dao {
        @Override
        public void add() {
            System.out.println("添加用户");
        }
    }
    //代理类
    public static class UserDaoProxy implements Dao {
        private UserDao userDao;
        public UserDaoProxy(UserDao userDao) {
            this.userDao = userDao;
        }
        @Override
        public void add() {
            System.out.println("add()开始执行");
            long s = System.currentTimeMillis();
            //核心业务逻辑要交给被代理者完成
            userDao.add();
            long e = System.currentTimeMillis();
            System.out.println("add()执行结束");
            System.out.println("add()耗时（ms）：" + (e-s));
        }
    }
}