大话设计模式二：策略模式（商场促销）
策略模式：它定义了算法家族，分别封装起来，让它们之间可以相互替换，此模式让算法的变化，不会影响到使用的算法客户。 </span> 应用案例：商场促销的多样性（折扣，满减，积分） 策略模式就是用来封装算法的，在实践中，我们发现可以用来封装几乎任何类型的规则，只要在分析中听到需要在不同时间应用不同的业务规则，就可以考虑使用策略模式处理这种变化的可能性。 package Strategy; abstract class CashSuper { public abstract double acceptCash(double money); } class CashNormal extends CashSuper { @Override public double acceptCash(double money) { return money; } } class CashRebate extends CashSuper { private double moneyRebate = 1d; public CashRebate(String moneyRebate) { this.moneyRebate = Double.parseDouble(moneyRebate); } @Override public double acceptCash(double money) { return money * moneyRebate; } } class CashReturn extends CashSuper { private double moneyCondition = 0.0d; private double moneyReturn = 0.0d; public CashReturn(String moneyCondition, String moneyReturn) { this.moneyCondition = Double.parseDouble(moneyCondition); this.moneyReturn = Double.parseDouble(moneyReturn); } @Override public double acceptCash(double money) { double result = money; if (money >= moneyCondition) { result = money - Math.floor(money / this.moneyCondition) * this.moneyReturn; } return result; } } public class CashContext { private CashSuper cs; public CashContext(String type) { switch(type) { case "正常收费": cs = new CashNormal(); break; case "满300返100": cs = new CashReturn("300","100"); break; case "打8折": cs =new CashRebate("0.8"); break; } } public double GetResult(double money) { return cs.acceptCash(money); } public static void main(String[] args) { // TODO Auto-generated method stub CashContext cc = null; double total = 0.0d,totalprice = 1000d; cc = new CashContext("正常收费"); total = cc.GetResult(totalprice); System.out.println(total); total = 0.0d; totalprice = 1000d; cc = new CashContext("满300返100"); total = cc.GetResult(totalprice); System.out.println(total); total = 0.0d; totalprice = 1000d; cc = new CashContext("打8折"); total = cc.GetResult(totalprice); System.out.println(total); } }