设计模式---策略模式

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只是自己日常做一些笔记

采用策略模式模拟一次专卖店的计价操作

Strategy类

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:17 PM

 * Desc:定义计算价格的接口 

 */
public interface Strategy {
    /**
     * @param goodsPrice 原价
     * @return 实际价格
     */
    double calcPrice(double goodsPrice);
}

具体的计算策略
普通用户的购物计价规则

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:19 PM

 * Desc: 普通用户的价格计算策略

 */
public class NormalCustomerStrategy implements Strategy {
    @Override
    public double calcPrice(double goodsPrice) {
        System.out.println("普通用户没有折扣");
        return goodsPrice;
    }
}

VIP用户

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:20 PM

 * Desc:VIP的价格计算策略 

 */
public class VipStrategy implements Strategy {
    @Override
    public double calcPrice(double goodsPrice) {
        System.out.println("VIP客户价格打八折");
        return goodsPrice * 0.8;
    }
}

超级VIP

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:21 PM

 * Desc: 超级VIP计算策略

 */
public class SVipStrategy implements Strategy {
    @Override
    public double calcPrice(double goodsPrice) {
        System.out.println("超级VIP用户7折!");
        return goodsPrice * 0.7;
    }
}

Calculator计算器

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:25 PM

 * Desc: 相当于Context

 */
public class Calculator {
    /**
     * Context 持有一个策略对象
     */
    private Strategy strategy = null;

    public Calculator(Strategy strategy) {
        this.strategy = strategy;
    }

    /**
     * 原价
     *
     * @param originPrice 商品原价
     * @return 不同用户的对应的价格
     */
    public double calcPrice(double originPrice) {
        return strategy.calcPrice(originPrice);
    }

    public void changeStrategy(Strategy strategy) {
        this.strategy = strategy;
    }
}

Client

package com.mjt.learning.pattern.strategy;

/**
 * Copyright:Learning
 * Author: liyang 

 * Date:2019/3/6 5:28 PM

 * Desc: 

 */
public class Client {
    public static void main(String[] args) {
        double price=100d;
        Strategy strategy=new NormalCustomerStrategy();
        Calculator calculator=new Calculator(strategy);
        System.out.println(calculator.calcPrice(price));

        strategy=new VipStrategy();
        calculator.changeStrategy(strategy);
        System.out.println(calculator.calcPrice(price));

        strategy=new SVipStrategy();
        calculator.changeStrategy(strategy);
        System.out.println(calculator.calcPrice(price));
    }
}

打印结果

普通用户没有折扣
100.0
VIP客户价格打八折
80.0
超级VIP用户7折!
70.0