public interface Goods {public double getPrice();
}

public class Goods_Book implements Goods{@Overridepublic double getPrice() {return 40;}}

public class Goods_Clothes implements Goods{@Overridepublic double getPrice() {return 200;}
}

public interface StrategyInterface {/*** 计算商品价格* @param goods* @return*/double culPrice(Goods goods);//接口中的方法默认public
}

/*** 高级会员 打折策略* @author Administrator**/
public class StrategyA implements StrategyInterface {@Overridepublic double culPrice(Goods goods) {System.out.println("高级会员，打8折");return goods.getPrice() * 0.8;}}

/*** 中级会员 打折策略* @author Administrator**/
public class StrategyB implements StrategyInterface {@Overridepublic double culPrice(Goods goods) {System.out.println("中级会员，打9折");return goods.getPrice() * 0.9;}
}

/*** 普通会员 打折策略* @author Administrator**/
public class StrategyC implements StrategyInterface {@Overridepublic double culPrice(Goods goods) {System.out.println("普通会员，不打折");return goods.getPrice();}
}

public class Price {private Goods goods;//商品种类private StrategyInterface strategy;//打折策略public Price(Goods goods, StrategyInterface strategy) {this.goods = goods;this.strategy = strategy;}/*** 根据商品种类和打折策略计算折后价格* @return*/public double culPrice(){return this.strategy.culPrice(goods);}
}

/*** 策略模式:*     并不决定在何时使用何种算法。*     在什么情况下使用什么算法是由客户端(即Test类)决定的。* @author Administrator**/
public class Test {public static void main(String[] args) {//定义何种商品和策略
//        Goods goods = new Goods_Book();Goods goods = new Goods_Clothes();StrategyInterface strategy = new StrategyA();
//        StrategyInterface strategy = new StrategyB();
//        StrategyInterface strategy = new StrategyC();
        System.out.println("原价："+goods.getPrice()+",折后价："+new Price(goods, strategy).culPrice());}
}

高级会员，打8折
原价：200.0,折后价：160.0

中级会员，打9折
  原价：200.0,折后价：180.0

...