和Template一样的目的,只不过实现手法是组合 而不是Template模式的继承,解决了继承所带来的弊端。
问题:
为了给业务逻辑(算法)具体的实现和抽象的接口之间的解耦。
把算法 (业务逻辑)封装到一个Contex类中通过组合的方式,实现在组合对象中,通过委托的方式将抽象接口的实现委托给组合对象的实现State模式也有类似区别
定义了一些列的算法,并且封装起来,使他们可以相互替换,策略模式让算法独立于客户的变化而独立变化
#include "PublicHeaders.h"
class Strategy
{
public:
virtual void AlgrithmInterface() = 0;
};
class ConCreateStrategy :public Strategy
{
public:
void AlgrithmInterface()override
{
cout << __FUNCTION__ << endl;
}
};
class Contex
{
public:
Contex(Strategy *strategy)
{
this->strategy = strategy;
}
void DoAction()
{
this->strategy->AlgrithmInterface();
}
private:
Strategy*strategy;
};
/**
* @brief test function for strategy pattern
*/
void testStrategy()
{
Contex* contex = new Contex(new ConCreateStrategy);
contex->DoAction();
}
例2
武器系统
class WeaponStrategy
{
public:
virtual void doFire() = 0;
};
class GaTlingGun_Strategy :public WeaponStrategy
{
public:
virtual void doFire()override
{
}
};
class PistolGun_Strategy :public WeaponStrategy
{
public:
virtual void doFire()override
{
}
};
class PlayerContex
{
public:
void Fire()
{
weapon->doFire();
}
void setWeapon(WeaponStrategy *strategy)
{
this->weapon = strategy;
}
WeaponStrategy*weapon;
};
void test()
{
PlayerContex*player = new PlayerContex;
player->setWeapon(new GaTlingGun_Strategy);
player->Fire();
}