策略模式

感觉策略模式跟简单工厂模式差不多。

策略模式首先定义一个策略的抽象类，每一个具体的策略都是继承这个抽象类

然后定义一个上下文类，类里面一个策略对象，类里有策略的对应方法，方法体关联策略对象的方法

使用策略的时候就直接调用上下文的方法就好了

 

package com.factory;

public abstract class CashSuper {
    protected double price;
    protected int count;
    public abstract double acceptCash();
    
}

class CashNormal extends CashSuper{

    @Override
    public double acceptCash() {
        double result=price*count;
        return result;
    }
    
    public CashNormal(double price,int count){
        this.price=price;
        this.count=count;
    }
    
}

class CashRebate extends CashSuper{
    private double moneyRebate;

    @Override
    public double acceptCash() {
        double result=0;
        result=price*count*moneyRebate;
        return result;
    }
    
    public CashRebate(double price,int count,double moneyRebate){
        this.price=price;
        this.count=count;
        this.moneyRebate=moneyRebate;
    }
        
}

class CashReturn extends CashSuper{
    private double get;
    private double back;

    @Override
    public double acceptCash() {
        double result=price*count;
        int x=(int)(result/get);
        result=result-x*back;
        return result;
    }
    
    public CashReturn(double price,int count,double get,double back){
        this.price=price;
        this.count=count;
        this.get=get;
        this.back=back;
    }
}

package com.factory;

public class CashContext {
    CashSuper cash;
    public CashContext(CashSuper cash){
        this.cash=cash;
    }
    public double acceptCash(){
        return cash.acceptCash();
    }

}

package com.strategy;

import java.util.Scanner;

public class Test {
    public static void main(String[] args){
        Scanner input=new Scanner(System.in);
        System.out.println("选择消费策略（A正常、B8折、C满500送100）：");
        char type=input.next().charAt(0);
        System.out.println("输入单价、数量：");
        double price=input.nextDouble();
        int count=input.nextInt();
        double result=0;
        CashContext context=null;
        switch(type){
        case 'A':
            context=new CashContext(new CashNormal(price,count));
            break;
        case 'B':
            context=new CashContext(new CashRebate(price, count, 0.8));
            break;
        case 'C':
            context=new CashContext(new CashReturn(price,count,500,100));
            break;
        default:
            context=new CashContext(new CashNormal(price,count));
        }
        result=context.acceptCash();
        System.out.println("应收"+result);
    }

}

 

上面仅仅使用的是策略模式，其实达到的效果不是很好，下面和简单工厂模式结合使用下：

package com.strategy;

public class CashContext {/*这里使用了一点简单工厂模型*/
    CashSuper cash;
    public CashContext(double price,int count,Character type){
        switch(type){
        case 'A':
            cash=new CashNormal(price,count);
            break;
        case 'B':
            cash=new CashRebate(price,count,0.8);
            break;
        case 'C':
            cash=new CashReturn(price,count,500,100);
            break;
        default:
            cash=new CashNormal(price,count);
        }
    }
    public double acceptCash(){
        return cash.acceptCash();
    }

}

package com.strategy;

import java.util.Scanner;

public class Test {
    public static void main(String[] args){
        Scanner input=new Scanner(System.in);
        System.out.println("选择消费策略（A正常、B8折、C满500送100）：");
        char type=input.next().charAt(0);
        System.out.println("输入单价、数量：");
        double price=input.nextDouble();
        int count=input.nextInt();
        double result=0;
        CashContext context=new CashContext(price,count,type);
        
        result=context.acceptCash();
        System.out.println("应收"+result);
    }

}