策略模式----Java

策略模式：就是针对一个问题在不同的情形下有不同的解决算法，为了灵活处理，可增减算法，就是用策略模式

感觉和简单工厂模式有些形似。。。。。

例：超市收银问题

针对不同的情况，有不打折的，打折的，还有满300返100的，等等。。。。

1、建个接口，它是各种模式抽象出来的公共方法

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public interface CashSuper {public Double getReuslt(Double money);}

2、各个算法的实现类

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public class CashNormal implements CashSuper{@Overridepublic Double getReuslt(Double money) {return money;}}

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public class CashRebate implements CashSuper{private Double rebate = 0.8;public Double getRebate() {return rebate;}public void setRebate(Double rebate) {this.rebate = rebate;}/** * @param rebate */public CashRebate(Double rebate) {super();this.rebate = rebate;}@Overridepublic Double getReuslt(Double money) {return money*getRebate();}}

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public class CashReturn implements CashSuper{private Double original;private Double rebateMoney;public Double getOriginal() {return original;}public void setOriginal(Double original) {this.original = original;}public Double getRebateMoney() {return rebateMoney;}public void setRebateMoney(Double rebateMoney) {this.rebateMoney = rebateMoney;}/** * @param original * @param rebateMoney */public CashReturn(Double original, Double rebateMoney) {super();this.original = original;this.rebateMoney = rebateMoney;}@Overridepublic Double getReuslt(Double money) {if (money >= getOriginal()) {return money - getRebateMoney();}return money;}}

3、策略选择

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public class StrategyContext {CashSuper cashSuper = null;/** * @param cashSuper */public StrategyContext(int i) {switch (i) {case 1:cashSuper = new CashRebate(0.6);break;case 2:cashSuper = new CashReturn(300.0,100.0);break;default:cashSuper = new CashNormal();break;}}public Double getMoney(Double money){return cashSuper.getReuslt(money);}}

4、测试

/** *Jun 28, 2013 *Copyright(c)JackWang *All rights reserve *@Author <a href="mailto:[e-mail]">JackWang</a>*/package com.example.strategy;public class TestStrategy {public static void main(String[] args) {StrategyContext sc1 = new StrategyContext(0);System.out.println(sc1.getMoney(500.0));StrategyContext sc2 = new StrategyContext(1);System.out.println(sc2.getMoney(600.0));StrategyContext sc3 = new StrategyContext(2);System.out.println(sc3.getMoney(500.0));}}

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经过学习改编自《大话设计模式》