设计模式学习1-工厂方法模式

前几天接到吉威时代电话面试，问了一个设计模式的问题，这方面自己只是了解，但不是很熟悉，所以没回答上，于是决定现在开始学习这方面的知识，先从最简单的工厂方法模式开始：

这种模式其实就是新建一个Factory接口，每个产品都有各自的工厂继承自该接口，来生产不同的产品，以水果为例：

#include
class Fruit{
public:
    Fruit(){};
    virtual ~Fruit(){};
    virtual void sayHello(void)=0;
    virtual void showColor(void)=0;
};
class Apple:public Fruit{
public:
    Apple(){}
    ~Apple(){}
    void sayHello(void){std::cout<<"I am apple!"<<std::endl;}
    void showColor(void){std::cout<<"My color is red!"<<std::endl;}
};
class Banana:public Fruit{
public:
    Banana(){}
    ~Banana(){}
    void sayHello(void){std::cout<<"I am banana!"<<std::endl;}
    void showColor(void){std::cout<<"My color is yellow!"<<std::endl;}
};
class Factory{
public:
    Factory(){}
    virtual ~Factory(){}
    virtual Fruit* createFruit()=0;
};
class AppleFactory:public Factory{
public:
    AppleFactory(){}
    ~AppleFactory(){}
    Fruit* createFruit(){
        return new Apple();}
};
class BananaFactory:public Factory{
public:
    BananaFactory(){}
    ~BananaFactory(){}
    Fruit* createFruit(){
        return new Banana();}
};
int main()
{
    AppleFactory *af=new AppleFactory();
    Fruit *apple=af->createFruit();
    apple->sayHello();
    apple->showColor();

    BananaFactory *bf=new BananaFactory();
    Fruit *banana=bf->createFruit();
    banana->sayHello();
    banana->showColor();

    delete af;
    delete apple;
    delete bf;
    delete banana;
    return 0;
}