方法。

调用所有的算法，减少了各种算法和调用算法之间的耦合性。                                                

功能。

包括：正常收费、折扣7折、满100减5、1000积分抵扣1元。               

父类：Strategy类：提取各个子类的共有方法getRealMoney()方法。                                                     

import java.text.DecimalFormat;
/**
@Author: cxh
@CreateTime: 18/1/1 12:04
@ProjectName: JavaBaseTest
客户端:测试
*/
public class Client {
public static void main(String[] args) {
double result=0;
int flag=0;//0,1,2,3代表:正常价格 ;七折; 满100减去5;  积分抵扣现金
ContextStrategyRef cs;
for(int i=10;i<60;i+=10){
if(flag==0){
cs=new ContextStrategyRef("正常收费");
result+=cs.getSum(i);
flag++;
continue;
}else if(flag==1){
cs=new ContextStrategyRef("折扣7折");
result+=cs.getSum(i);
flag++;
continue;
}else if(flag==2){
cs=new ContextStrategyRef("满100减5");
result+=cs.getSum(i);
flag++;
}else if(flag==3){
cs=new ContextStrategyRef("1000积分抵扣1元");
result+=cs.getSum(i);
flag=0;
}
}
//保留2位小数
DecimalFormat df=new DecimalFormat("#.00");
System.out.println(df.format(result));
}
}<span style="text-align:justify;">        <span style="text-align:justify;">  <span style="text-align:justify;">                                                                          <span style="text-align:justify;">          <span style="text-align:justify;"> 

/**
@Author: cxh
@CreateTime: 18/1/1 11:20
@ProjectName: JavaBaseTest
*/
public class Strategy {
public double getRealMoney(double money){
return -1D;
}
}

/**
@Author: cxh
@CreateTime: 18/1/1 11:21
@ProjectName: JavaBaseTest
打折策略类
*/
public class StrategyA extends Strategy {
private double discount;//折扣
public StrategyA(double discount){
this.discount=discount;
}
//获取折扣后的金额
@Override
public double getRealMoney(double money) {
return money*discount;
}
}

/**
@Author: cxh
@CreateTime: 18/1/1 11:25
@ProjectName: JavaBaseTest
满减 类
*/
public class StrategyB extends Strategy {
private int condition,mongeyReturn;
public StrategyB(int condition,int mreturn){
this.condition=condition;
this.mongeyReturn=mreturn;
}
@Override
public double getRealMoney(double money) {
if(money>=condition)
return money-mongeyReturn;
else
return money;
}
}

/**
@Author: cxh
@CreateTime: 18/1/1 11:38
@ProjectName: JavaBaseTest
积分抵扣现金 类
/
public class StrategyC extends Strategy {
@Override
public double getRealMoney(double money) {
//积分得从账户获取,所以这里就用一个[1,10]的随机数字代表
return money-10Math.random();
}
}

/**
@Author: cxh
@CreateTime: 18/1/1 11:45
@ProjectName: JavaBaseTest
*/
public class ContextStrategyRef {
private Strategy strategy;//保持对 促销策略的引用.
//构造函数,确定实例化哪一个类
public ContextStrategyRef(String selectedItem){
switch (selectedItem){
case "正常收费":
strategy=new StrategyA(1);
break;
case "折扣7折":
strategy=new StrategyA(0.7);
break;
case "满100减5":
strategy=new StrategyB(100,5);
break;
case "1000积分抵扣1元":
strategy=new StrategyC();
 }
}
public double getSum(double money){
return strategy.getRealMoney(money);
}
}