设计模式之装饰模式

装饰模式

1.功能

将主功能和附加功能分开

 

2.好处

(1)使主功能和附加功能可以独立扩展

(2)降低主功能和附加功能之间的耦合度

 

3.基本类图

 

内存中:

4.装饰模式的一个具体事例

(1)类图

(2)代码实现如下

#include <iostream>
using namespace std;

class Base{
	private:
		Base * next;
	public:
		Base(Base*t){
			next=t;
		}
		
		virtual void fun(){
			if(next){
				next->fun();
			}
		}
		
		virtual ~Base(){
			delete next;
			cout<<"Base的析构函数"<<endl; 
		} 
};

class productA: public Base{
	public:
		productA(Base *t):Base(t){
		}
		~productA(){
			cout<<"productA的析构函数"<<endl; 
		}
};

class productB: public Base{
	public:
		productB(Base *t):Base(t){
		}
		~productB(){
			cout<<"productB的析构函数"<<endl; 
		}
};

class Decorator:public Base{
	public:
		Decorator(Base*t):Base(t){
		}
		virtual void fun()=0;//保证接口继承统一性,也可以不写
		virtual ~Decorator(){
			cout<<"Decorator的析构函数"<<endl; 
		} 
};

class DecoratorA:public Decorator{
	public:
		DecoratorA(Base*t):Decorator(t){
		}
		void fun(){
			cout<<"DecoratorA的fun函数..."<<endl;
			Base::fun(); 
		}
	~DecoratorA(){
			cout<<"DecoratorA的析构函数..."<<endl;
		}
};

class DecoratorB:public Decorator{
	public:
		DecoratorB(Base*t):Decorator(t){
		}
		void fun(){
			cout<<"DecoratorB的fun函数..."<<endl;
			Base::fun(); 
		}
		~DecoratorB(){
			cout<<"DecoratorB的析构函数..."<<endl;
		}
	
};

class DecoratorC:public Decorator{
	public:
		DecoratorC(Base*t):Decorator(t){
		}
		void fun(){
			cout<<"DecoratorC的fun函数..."<<endl;
			Base::fun(); 
		}
		
		~DecoratorC(){
			cout<<"DecoratorC的析构函数..."<<endl;
		}
	
};

int main(void){
	Base*head=NULL;
	head=new DecoratorB(head);
	head=new DecoratorA(head);
	head=new productA(head);
	head->fun();
	delete head;
}

执行结果如下

DecoratorA的fun函数...
DecoratorB的fun函数...
productA的析构函数
DecoratorA的析构函数...
Decorator的析构函数
DecoratorB的析构函数...
Decorator的析构函数
Base的析构函数
Base的析构函数
Base的析构函数