设计模式-创建-Factory(工厂)模式
目的：统一对象创建接口，类的具体化延迟到子类
对象很多时，对象的创建就会很复杂 多样，
工厂模式规定了统一创建接口，提高内聚 ，解耦
定义创建对象的接口，封装了对象的创建；
使得具体化类的工作延迟到了子类中。
工厂模式有好几种形式
- 简单的静态接口函数，
- class Product
- {
- public:
- /**
- * @brief create a Product
- */
- static Product *create()
- {
- return new Product;
- }
- private:
- Product(){}
- };
2. 抽象工厂类创建1
- class Product
- {
- public:
- Product(){}
- };
- class Factory
- {
- public:
- virtual Product * create() = 0;
- };
- class ProductFactory : public Factory
- {
- public:
- virtual Product *create()override
- {
- return new Product;
- }
- };
- int main(int argc, char *argv[])
- {
- Factory * factory = new ProductFactory;
- Product* product = factory->create();
- system("pause");
- return 0;
- }
- //还可以进一步 对访问权限封装
3.模板工厂类创建
- class Product
- {
- public:
- void init(){ cout << __FUNCTION__ << endl; };
- Product(){}
- };
- template< class T>
- class Factory
- {
- public:
- Factory(){};
- virtual T *create();
- };
- template<>
- class Factory<Product>
- {
- public:
- Factory(){};
- virtual Product *create()
- {
- auto ins = new Product;
- ins->init();
- return ins;
- }
- };
- int main(int argc, char *argv[])
- {
- auto *factory = new Factory<Product>();
- factory->create();
- return 0;
- }
- //也可以用模板函数创建，各自的特化版本
4.抽象工厂创建2
- class Fruit
- {
- public:
- Fruit(){}
- };
- class Apple :public Fruit
- {
- public: Apple(){};
- };
- class Peach :public Fruit
- {
- public: Peach(){};
- };
- class Factory
- {
- public:
- virtual Fruit *createApple() = 0;
- virtual Fruit *createPeach() = 0;
- };
- class FruitFactory : public Factory
- {
- public:
- Fruit *createApple()override
- {
- return new Apple;
- }
- Fruit *createPeach()override
- {
- return new Peach;
- }
- };
- int main(int argc, char *argv[])
- {
- Factory * factory = new FruitFactory;
- Fruit* apple = factory->createApple();
- Fruit *peach = factory->createPeach();
- system("pause");
- return 0;
- }