装饰器Decorator：主要是增加现有类的功能
通过子类实现功能增强的问题：为了增强现有类的功能，通过实现子类的方式，重写接口，是可以完成功能扩展的，但是代码中有太多的子类添加进来了
class Car//抽象基类 { public: virtual void show() = 0; }; //三个实体的汽车类 class Bmw : public Car { public: void show() { cout << "这是一辆宝马汽车，配置有：基本配置"; } }; class Audi : public Car { public: void show() { cout << "这是一辆奥迪汽车，配置有：基本配置"; } }; class Benz : public Car { public: void show() { cout << "这是一辆奔驰汽车，配置有：基本配置"; } }; //装饰器 class ConcreteDecorator01 : public Car { public: ConcreteDecorator01(Car *p) : pCar(p) {}; void show() { pCar->show(); cout << ", 定速巡航"; } private: Car *pCar; }; class ConcreteDecorator02 : public Car { public: ConcreteDecorator02(Car *p) : pCar(p) {}; void show() { pCar->show(); cout << ", 自动刹车"; } private: Car *pCar; }; class ConcreteDecorator03 : public Car { public: ConcreteDecorator03(Car *p) : pCar(p) {}; void show() { pCar->show(); cout << ", 车道偏离"; } private: Car *pCar; }; int main() { Car *p1 = new ConcreteDecorator01(new Bmw()); p1 = new ConcreteDecorator02(p1); p1->show(); cout << endl; Car *p2 = new ConcreteDecorator02(new Audi()); p2->show(); cout << endl; Car *p3 = new ConcreteDecorator03(new Benz()); p3->show(); cout << endl; return 0; }
这是一辆宝马汽车，配置有：基本配置, 定速巡航, 自动刹车 这是一辆奥迪汽车，配置有：基本配置, 自动刹车 这是一辆奔驰汽车，配置有：基本配置, 车道偏离
