Q：策略模式的特点

A：

1. 具体算法从具体的业务方法中独立出来
2. 策略模式是同行为的不同实现

Q：什么时候使用策略模式

A：多个if-else使用策略模式

收费对象类

public class CashContext {private CashStrategy cashStrategy;public double getMoney(double money) {return cashStrategy.acceptCash(money);}
}

收费策略接口

public interface CashStrategy { double acceptCash(double money); }

正常收费类

public class NormalCash implements CashStrategy {@Overridepublic double acceptCash(double money) {return money;}
}

打折收费类

public class RebateCash implements CashStrategy {private double discounts = 10;@Overridepublic double acceptCash(double money) {return money * discounts / 10;}
}

返利收费类

public class ReturnCash implements CashStrategy {private double condition = 0;private double rebate = 0;@Overridepublic double acceptCash(double money) {if (money >= condition) {money -= Math.floor(money / condition) * rebate;}return money;}
}

演示类

public class Demo {public static void main(String[] args) {String discounts = "满300减100";CashContext cc = new CashContext();switch (discounts) {case "正常收费":cc.setCashStrategy(new NormalCash());break;case "打9折":cc.setCashStrategy(new RebateCash(9));break;case "满300减100":cc.setCashStrategy(new ReturnCash(300, 100));break;}double price = 400;double money = cc.getMoney(price);System.out.println("优惠后的费用为:" + money);}
}