《職責鏈模式》

職責鏈模式，用我的理解就是動作的處理鏈表。根據請求的不同類型，在鏈表查找相應類型的處理者。處理者是一個鏈表。

用下面的一個圖來解釋

 

基本的UML圖爲

// ChainofResponsibility.cpp : 定義控制檯應用程序的入口點。
//************************************************************************/
/* @filename    ChainofResponsibility.cpp
@author       wallwind
@createtime    2012/11/6 11:58
@function     責任鏈模式
@email       [email protected]
@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;
}