策略模式

 

同一个物品，有不同策略的情况。将算数封装成策略，根据实际情况调用策略。

下面是英雄选用不同战斗方式的策略。代码如xia :

#define  _CRT_SECURE_NO_WARNINGS 
#include <iostream>

using namespace std;


//抽象的策略（抽象的武器）
class AbstractStrategy
{
public:
    //纯虚函数， 使用具体武器的策略,
    virtual void useWeapon() = 0;
};

class KnifeStrategy :public AbstractStrategy
{
public:
    virtual void useWeapon() {
        cout << "使用匕首，进行近战攻击" << endl;
    }
};

class AkStrategy :public AbstractStrategy
{
public:
    virtual void  useWeapon() {
        cout << "使用ak 进行远程攻击" << endl;
    }
};


class Hero
{
public:
    Hero()
    {
        strategy = NULL;
    }

    void setStrategy(AbstractStrategy *strategy)
    {
        this->strategy = strategy;
    }

    //攻击方法
    void fight() {
        cout << "英雄开始战斗了" << endl;
        this->strategy->useWeapon();
    }

private:
    //拥有一个 使用攻击策略的抽象成员
    AbstractStrategy *strategy;
};

int main(void)
{
    AbstractStrategy *knife = new KnifeStrategy;
    AbstractStrategy *ak47 = new AkStrategy;

    Hero *hero = new Hero;

    cout << "远程兵来了， 更换远程攻击" << endl;
    hero->setStrategy(ak47);
    hero->fight();

    cout << "近战兵 来了， 更换近战的攻击" << endl;
    hero->setStrategy(knife);
    hero->fight();


    
    return 0;
}

 

下面是一个商品上午和下午不同的营销策略。代码如下

#define  _CRT_SECURE_NO_WARNINGS 
#include <iostream>

using namespace std;

//销售策略
class AbstractStrategy
{
public:
    //商品具体的销售策略计算方式
    virtual double getPrice(double price) = 0;
};

//策略A  商品打八折
class StrategyA :public AbstractStrategy
{
public:
    virtual double getPrice(double price)  {
        return price*0.8;
    }
};

//策略B 如果商品超过200， 减100
class StrategyB :public AbstractStrategy
{
public:
    virtual double getPrice(double price)
    {
        if (price > 200) {
            price = price - 100;
        }

        return price;
    }
};


//商品
class Item
{
public:
    Item(string name, double price)
    {
        this->name = name;
        this->price = price;
    }

    //提供一个可以更换策略的方法
    void setStrategy(AbstractStrategy *strategy)
    {
        this->strategy = strategy;
    }

    //最终获得商品的价格的方法
    double SellPrice()
    {
        return this->strategy->getPrice(this->price);
    }
private:
    string name;
    double price;//商品的价格
    //销售的策略
    AbstractStrategy *strategy;
};


int main(void)
{
    Item it("nike鞋", 201);
    AbstractStrategy *sA = new StrategyA;
    AbstractStrategy *sB = new StrategyB;

    cout << "上午 商场执行 销售策略A 全程八折" << endl;
    it.setStrategy(sA); //让商品设置A销售策略
    cout << "nike鞋应该卖" << it.SellPrice() << endl;

    cout << "-----" << endl;
    cout << "下午商场执行 销售策略B， 全场 超200减100" << endl;
    it.setStrategy(sB);
    cout << "nike鞋应该卖" << it.SellPrice() << endl;
    
    return 0;
}