设计模式-策略模式

折扣策略接口

public interface DiscountStrategy { /** * 计算价格 */ public double calcPrice(double booksPrice); }

普通会员折扣

public class NormalStrategy implements DiscountStrategy { @Override public double calcPrice(double price) { System.out.println("普通会员的没有折扣"); return price; } }

中级会员折扣

public class MiddleStrategy implements DiscountStrategy { @Override public double calcPrice(double price) { System.out.println("中级会员9折"); return price * 0.9; } }

高级会员折扣

public class HighStrategy implements DiscountStrategy { @Override public double calcPrice(double price) { System.out.println("高级会员8折"); return price * 0.8; } }

价格类

public class Price { //持有一个具体的策略对象 private Strategy strategy; /** * 构造函数，传入一个具体的策略对象 * @param strategy 具体的策略对象 */ public Price(Strategy strategy){ this.strategy = strategy; } /** * 计算价格 */ public double getFinalPrice(double price){ return this.strategy.calcPrice(price); } }

场景类

public class Client { public static void main(String[] args) { //选择并创建需要使用的策略对象 Strategy strategy = new MiddleStrategy(); //创建环境 Price price = new Price(strategy); //计算价格 double finalPrice = price.getFinalPrice(300); System.out.println("最终价格为：" + finalPrice); } }