创建型模式 抽象工厂

 

 

 

 

 

 

/** * 创建型模式 抽象工厂 * 抽象工厂模式是所有形态的工厂模式中最为抽象和最其一般性的。抽象工厂模式可以向客户端提供一个接口，使得客户端在不必指定产品的具体类型的情况下，能够创建多个产品族的产品对象。 * * 抽象工厂（Creator）角色    * 抽象工厂模式的核心，包含对多个产品结构的声明，任何工厂类都必须实现这个接口。    * 具体工厂（ Concrete  Creator）角色   * 具体工厂类是抽象工厂的一个实现，负责实例化某个产品族中的产品对象。 * 抽象（Product）角色   * 抽象模式所创建的所有对象的父类，它负责描述所有实例所共有的公共接口。    * 具体产品（Concrete Product）角色   * 抽象模式所创建的具体实例对象 * */#include 
     
      class Fruit{public:    virtual void sayname()    {        std::cout << "I'am fruit" << std::endl;    }    virtual ~Fruit() {}};class FruitFactory{public:    virtual Fruit * CreateBanana()    {        return new Fruit();    }    virtual Fruit * CreatePear()    {        return new Fruit();    }    virtual ~FruitFactory() {}};class SouthBanana: public Fruit{public:    virtual void sayname() override    {        std::cout << "South Banana" << std::endl;    }};class NorthBanana: public Fruit{public:    virtual void sayname() override    {        std::cout << "North Banana" << std::endl;    }};class SouthPear: public Fruit{public:    virtual void sayname() override    {        std::cout << "South Pear" << std::endl;    }};class NorthPear: public Fruit{public:    virtual void sayname() override    {        std::cout << "North Pear" << std::endl;    }};// 在C++中，只要原来的返回类型是指向类的指针或引用，新的返回类型是指向派生类的指针或引用，覆盖的方法就可以改变返回类型。这样的类型称为协变返回类型（Covariant returns type).class SouthFactory: public FruitFactory{public:    virtual SouthBanana * CreateBanana() override    {        return new SouthBanana();    }    virtual SouthPear * CreatePear() override    {        return new SouthPear();    }};// 在C++中，只要原来的返回类型是指向类的指针或引用，新的返回类型是指向派生类的指针或引用，覆盖的方法就可以改变返回类型。这样的类型称为协变返回类型（Covariant returns type).class NorthFactory: public FruitFactory{public:    virtual NorthBanana * CreateBanana() override    {        return new NorthBanana();    }    virtual NorthPear * CreatePear() override    {        return new NorthPear();    }};void mytest(){    FruitFactory * factory = nullptr;    Fruit * fruit = nullptr;    factory = new SouthFactory();    fruit = factory->CreateBanana();    fruit->sayname();    delete fruit;    fruit = nullptr;    fruit = factory->CreatePear();    fruit->sayname();    delete fruit;    fruit = nullptr;    delete factory;    factory = nullptr;    factory = new NorthFactory();    fruit = factory->CreateBanana();    fruit->sayname();    delete fruit;    fruit = nullptr;    fruit = factory->CreatePear();    fruit->sayname();    delete fruit;    fruit = nullptr;    delete factory;    factory = nullptr;    return;}int main(){    mytest();    system("pause");    return 0;}