某大型购物中心欲开发一套收银软件，要求其能够支持购物中心在不同时期推出的各种促销活动，如打折、返利(例如，满300返100),等等。现采用策略(Strategy)模式实现该要求，得到如图7.13 所示的类图。

【Java 代码】

import java.util.*;
enum TYPE { NORMAL,CASH_DISCOUNT,CASH_RETURN};
interface Cashsuper {public double acceptCash(double money);
}
class CashNormal implements CashSuper{// 正常收费子类public double accptCash(double money){return money;}
}
class CashDiscount implements Cashsuper {private double moneyDiscount;    //折扣率public CashDiscount(double moneyDiscount){this moneyDiscount = moneyDiscount;}public double acceptCash(double money){return money* moneyDiscount;}
}
class CashReturn implements Cashsuper {  //满额返利private double moneyCondition;private double moneyReturn;public CashReturn(double moneyCondition, double moneyReturn){this.moneycondition =moneyCondition;//满额数额this.moneyReturn =moneyReturn;//返利数额}public double acceptCash(double money){double result = money;if (money >= moneyCondition )result=money-Math.floor(money/moneyCondition )* moneyReturn;return result;}
}
class CashContext_{private Cashsuper cs;private TYPE t;public CashContext(TYPE t){switch(t){case NORMAL;// 正常收费cs= new CashNormal();break;case CASH RETURN;//满300返100cs = new CashReturn(300,100);break;case CASH_ DISCOUNT;//打8折cs =new CashDiscount(0.8);break;}}public double GetResult(double money){return cs.acceptCash(money);}//此处略去main()函数
}