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目录

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1.意图

  动态地给一个对象加入额外的方法/行为。

  装饰者为它的子类提供了灵活的扩展方法/函数的行为。

2.UML类图

 

3.代码实现

#include
   
    #include
    
     using namespace std;//we are going to decorate a houseclass House{public:	virtual void draw() = 0;	virtual string getDescription() = 0;	virtual ~House() {}};class SimpleHouse: public House{public:	void draw() {}	string getDescription() {		return "simple house\n";	}};class HouseDecorator: public House{protected:	House *decoratedHouse;public:	HouseDecorator(House *hs):decoratedHouse(hs){}};//Indoorclass IndoorDecorator:public HouseDecorator{public:	IndoorDecorator(House *hs):HouseDecorator(hs) {}	void draw() {		drawIndoor();		decoratedHouse->draw();	}	string getDescription() {		return decoratedHouse->getDescription() + "with Indoor\n";	}private:	void drawIndoor(){ }};//Outdoorclass OutdoorDecorator: public HouseDecorator{public:	OutdoorDecorator(House *hs):HouseDecorator(hs) { }	void draw() {		drawOutdoor();		decoratedHouse->draw();	}	string getDescription() {		return  decoratedHouse->getDescription() + "with Outdoor\n";	}private:	void drawOutdoor() {}};int main(){	House *hs=new SimpleHouse();	std::cout<
     
      getDescription()<
      
       getDescription()<
       
        getDescription()<
        
         getDescription()<
        
       
      
     
    
   

运行结果：

  simple house

  simple house

  with Indoor

  simple house

  with Outdoor

  simple house

  with Outdoor   with Indoor

  分析：

  每一个component(House) 可以被它own或者wrapped装饰者使用。   ConcreteComponent(SimpleHouse)就是我们即将对其动态地增加方法(Outdoor/Indoor)的对象，继承自House。   每一个装饰者has-a(wraps) 一个componet,这意味着装饰者拥有一个指向House对象的指针(decoratedHouse成员)。