Decorator模式

Decorator模式解决以下情况：我们需要为一个已经定义好的类添加新的职责（操作），通常的情况我们会定义一个新类继承自定义好的类，这样会带来一个问题。通过继承的方式解决这样的情况还带来了系统的复杂性，因为继承的深度会变得很深。而Decorator模式提供了一种给类增加职责的方法，不是通过继承实现，而是通过组合。

Decorator.h

//Decorator.h
#ifndef _DECORATOR_H_
#define _DECORATOR_H_

class Component
{
public:
	virtual ~Component();
	virtual void Operation();
protected:
	Component();
private:
};

class ConcreteComponent:public Component
{
public:
	ConcreteComponent();
	~ConcreteComponent();
	void Operation();
protected:
private:
};

class Decorator:public Component
{
public:
	Decorator(Component* com);
	virtual ~Decorator();
	void Operation();
protected:
	Component* _com;
private:
};

class ConcreteDecorator:public Decorator
{
public:
	ConcreteDecorator(Component* com);
	~ConcreteDecorator();
	void Operation();
	void AddedBehavior();
protected:
private:
};
#endif //~_DECORATOR_H_

//Decorator.cpp
#include "Decorator.h"
#include <iostream>
Component::Component()
{

}
Component::~Component()
{

}
void Component::Operation()
{

}

ConcreteComponent::ConcreteComponent()
{ 

}
ConcreteComponent::~ConcreteComponent()
{

}
void ConcreteComponent::Operation()
{
	std::cout<<"ConcreteComponent operation..."<<std::endl;
}


Decorator::Decorator(Component* com)
{
	this->_com = com;
}
Decorator::~Decorator()
{
	delete _com;
}
void Decorator::Operation()
{

}

ConcreteDecorator::ConcreteDecorator(Component* com):Decorator(com)
{

}
ConcreteDecorator::~ConcreteDecorator()
{

}
void ConcreteDecorator::AddedBehavior()
{
	std::cout<<"ConcreteDecorator::AddedBehacior...."<<std::endl;
}
void ConcreteDecorator::Operation()
{
	_com->Operation();
	this->AddedBehavior();
}

#include "Decorator.h"

#include <iostream>
using namespace std;


int main(){
	Component* com = new ConcreteComponent();
    Decorator* dec = new ConcreteDecorator(com);

	dec->Operation();

	delete dec;

    return 0;
}

Decorator模式,布布扣,bubuko.com

Decorator模式

原文：http://blog.csdn.net/starcuan/article/details/20369401