用代码和UML图化解设计模式之《责任链模式》

责任链模式，用我的理解就是动作的处理链表。根据请求的不同类型，在链表查找相应类型的处理者。处理者是一个链表。

wiki上说明

wikipedia的定义为：CoR pattern consists of a source of command objects and a series of processing objects. Each processing object contains a set of logic that describes the types of command objects that it can handle, and how to pass off those that it cannot handle to the next processing object in the chain. A mechanism also exists for adding new processing objects to the end of this chain.

 

用下面的一个图来解释

 

基本的UML图为

// ChainofResponsibility.cpp : 定义控制台应用程序的入口点。
//************************************************************************/    
/* @filename    ChainofResponsibility.cpp
@author       wallwind  
@createtime    2012/11/6 11:58
@function     责任链模式
@email       wochenglin@qq.com  
@weibo      @成林有理想
*/    
/************************************************************************/

#include "stdafx.h"
#include <iostream>

using namespace std;

class IChain
{
public:
	IChain():m_nextChain(NULL)
	{

	}
	virtual ~IChain()
	{
		if (m_nextChain !=NULL)
		{
			delete m_nextChain;
			m_nextChain = NULL;
		}
	}

	void setChainHandler(IChain* handler)
	{
		m_nextChain = handler;
	}
	virtual void handleReq(int reqtype) = 0;

	
protected:
	IChain* m_nextChain;
	
};

class FirstHandler:public IChain
{
public:
	FirstHandler():IChain()
	{
	}
	virtual ~FirstHandler(){}

	virtual void handleReq(int reqtype)
	{
		if (reqtype <3)
		{
			cout<<"FirstHandler::handleReq"<<endl;
		}
		else if (m_nextChain !=NULL)
		{
			m_nextChain->handleReq(reqtype);
		}
		else
		{
			cout<<"no handler"<<endl;
		}
	}
};

class SecondHandler:public IChain
{
public:
	SecondHandler():IChain()
	{
		
	}
	virtual ~SecondHandler(){}

	virtual void handleReq(int reqtype)
	{
		if (reqtype <7)
		{
			cout<<"SecondHandler::handleReq"<<endl;
		}
		else if (m_nextChain !=NULL)
		{
			m_nextChain->handleReq(reqtype);
		}
		else
		{
			cout<<"no handler"<<endl;
		}
	}


	
};

class ThirdHandler:public IChain
{
public:
	ThirdHandler():IChain()
	{
	}
	virtual ~ThirdHandler(){}

	virtual void handleReq(int reqtype)
	{
		if (reqtype <9)
		{
			cout<<"ThirdHandler::handleReq"<<endl;
		}
		else if (m_nextChain !=NULL)
		{
			m_nextChain->handleReq(reqtype);
		}
		else
		{
			cout<<"no handler"<<endl;
		}
	}


};

int _tmain(int argc, _TCHAR* argv[])
{

	IChain *p1handler= new FirstHandler;
	IChain *p2handler= new SecondHandler;
	IChain *p3handler= new ThirdHandler;

	p1handler ->setChainHandler(p2handler);
	p2handler->setChainHandler(p3handler);

	p3handler ->handleReq(4);

	delete p1handler,p2handler,p3handler;
	return 0;
}