c++-工厂模式

本文描述了c++工厂模式基本概念和一个例子。

基本概念

  • 定义一个用于创建对象的接口,让子类决定实例化哪一个类。Factory Method使一个类的实例化延迟到其子类。又叫虚拟构造子(Virtual Constructor)模式或者多态性工厂(Polymorphic Factory)模式。
  • 工厂模式的好处:工厂模式就相当于创建实例对象的new。工厂模式也是用来创建实例对象的,可能多做一些工作,但会给你系统带来更大的可扩展性和尽量少的修改量。
  • 通常我们都要在创建sample实例时做点初始化的工作。
  • 需要将创建实例的工作与使用实例的工作分开, 也就是说,让创建实例所需要的大量初始化工作从Sample的构造函数中分离出去。
  • 工厂模式是一个创建性的模式,他要求工厂类和产品类分开,由一个工厂类可以根据传入的参量决定创建出哪一种产品类的实例。但这些不同的实例有共同的父类

例子

  • 文件:main.cpp
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#include <iostream>
using namespace std;

class IHuman
{
public:
IHuman(void)
{

}
~IHuman()
{

}
virtual void Laugh() = 0;
virtual void Cry() = 0;
virtual void Talk() = 0;

};

class WhiteHuman : public IHuman
{
public:
WhiteHuman(void)
{

}
~WhiteHuman(void)
{

}
void Laugh()
{
std::cout << "白种人笑!" << std::endl;
}
void Cry()
{
std::cout << "白种人哭!" <<std::endl;
}
void Talk()
{
std::cout << "白种人说话!" <<std::endl;
}
};

class YellowHuman : public IHuman
{
public:
YellowHuman(void)
{

}
~YellowHuman(void)
{

}
void Laugh()
{
std::cout << "黄种人笑!" << std::endl;
}
void Cry()
{
std::cout << "黄种人哭!" <<std::endl;
}
void Talk()
{
std::cout << "黄种人说话!" <<std::endl;
}
};

class BlackHuman : public IHuman
{
public:
BlackHuman(void)
{

}
~BlackHuman(void)
{

}
void Laugh()
{
std::cout << "黑种人笑!" << std::endl;
}
void Cry()
{
std::cout << "黑种人哭!" <<std::endl;
}
void Talk()
{
std::cout << "黑种人说话!" <<std::endl;
}
};


class IHumanFactory
{
public:
IHumanFactory(void)
{

}
~IHumanFactory(void)
{

}
virtual IHuman* CreateHuman() = 0;

};


class WhiteHumanFactory: public IHumanFactory
{
public:
WhiteHumanFactory(void)
{

}
~WhiteHumanFactory(void)
{

}
IHuman *CreateHuman()
{
return new WhiteHuman();
}

};

class YellowHumanFactory: public IHumanFactory
{
public:
YellowHumanFactory(void)
{

}
~YellowHumanFactory(void)
{

}
IHuman *CreateHuman()
{
return new YellowHuman();
}

};

class BlackHumanFactory: public IHumanFactory
{
public:
BlackHumanFactory(void)
{

}
~BlackHumanFactory(void)
{

}
IHuman *CreateHuman()
{
return new BlackHuman();
}

};


int main()
{
std::cout << "#1.制造黄种人"<<std::endl;
IHumanFactory *pHumanFactory = new YellowHumanFactory();
IHuman * pHuman = pHumanFactory->CreateHuman();
pHuman->Cry();
pHuman->Laugh();
pHuman->Talk();
delete pHuman;
delete pHumanFactory;

std::cout << "#1.制造白种人"<<std::endl;
IHumanFactory *pHumanFactory2 = new WhiteHumanFactory();
IHuman * pHuman2 = pHumanFactory->CreateHuman();
pHuman->Cry();
pHuman->Laugh();
pHuman->Talk();
delete pHuman2;
delete pHumanFactory2;

std::cout << "#1.制造黑种人"<<std::endl;
IHumanFactory *pHumanFactory3 = new BlackHumanFactory();
IHuman * pHuman3 = pHumanFactory->CreateHuman();
pHuman->Cry();
pHuman->Laugh();
pHuman->Talk();
delete pHuman3;
delete pHumanFactory3;

getchar();
return 0;

}

参考