扯淡设计模式2：java，模板模式，

package com.dayuanit.service;

public abstract class UserService {

    public void login(String userName, String pwd){
        System.out.println("login begin");

        first();
        second();
        third();

        System.out.println("login over");
    }

    public void first(){
        System.out.println("login 1");
    }
    protected abstract void second();
    public void third(){
        System.out.println("login 3");
    }

}

package com.dayuanit.authen;

import com.dayuanit.service.UserService;

public class AlipayAuthen extends UserService{
    @Override
    protected void second(){
        System.out.println("alipay login 2");
    }
}

package com.dayuanit.authen;

import com.dayuanit.service.UserService;

public class WeiXinAuthen extends UserService{

    @Override
    public void second(){
        System.out.println("weixin login 2");
    }
}

package com.dayuanit;

import com.dayuanit.authen.AlipayAuthen;
import com.dayuanit.authen.WeiXinAuthen;

public class Test {
    public static void main(String[] args) {

        //new UserService().login("tom", "111");
        new WeiXinAuthen().login("tom","111");
        System.out.println("--------------------------------");
        new AlipayAuthen().login("tom", "111");
    }
}