[行为型模式] 责任链模式的理解

头文件

//ChainOfResponsibilityPattern.h

#ifndef CHAIN_OF_RESPONSIBILITY_PATTERN_H
#define CHAIN_OF_RESPONSIBILITY_PATTERN_H

#include <Windows.h>
#include <iostream>
using namespace std;
#define SAFE_DELETE(p) if (p) { delete p; p = NULL; }

namespace ChainOfResponsibilityPattern
{
    //////////////////////////////////////////////////////////////////////////
    class HolidayRequest
    {
    public:
        HolidayRequest(int hour);
        int GetHour();

    private:
        int m_iHour;
    };

    //The holiday request handler interface
    class Manager
    {
    public:
        Manager();
        virtual ~Manager();
        virtual bool HandleRequest(HolidayRequest* pRequest) = 0;
    };

    // Project manager
    class PM : public Manager
    {
    public:
        PM(Manager *handler);
        virtual ~PM();
        bool HandleRequest(HolidayRequest* pRequest);

    private:
        Manager *m_pHandler;
    };

    // Department manager
    class DM : public Manager
    {
    public:
        DM(Manager *handler);
        virtual ~DM();
        bool HandleRequest(HolidayRequest* pRequest);

        // The department manager is in?
        bool IsIn();

    private:
        Manager *m_pHandler;
    };

    // Project supervisor
    class PS : public Manager
    {
    public:
        PS(Manager *handler);
        virtual ~PS();
        bool HandleRequest(HolidayRequest* pRequest);

    private:
        Manager *m_pHandler;
    };

    //////////////////////////////////////////////////////////////////////////
    void ChainOfResponsibilityPattern_Test();
}

#endif

实现

#include "ChainOfResponsibilityPattern.h"

namespace ChainOfResponsibilityPattern
{
    //////////////////////////////////////////////////////////////////////////
    HolidayRequest::HolidayRequest(int hour)
        : m_iHour(hour)
    {}

    int HolidayRequest::GetHour()
    {
        return m_iHour;
    }

    //////////////////////////////////////////////////////////////////////////
    Manager::Manager(){}
    Manager::~Manager(){}

    //////////////////////////////////////////////////////////////////////////
    PM::PM(Manager *handler)
        : m_pHandler(handler)
    {}

    PM::~PM()
    {}

    bool PM::HandleRequest(HolidayRequest *pRequest)
    {
        if (pRequest->GetHour() <= 2 || m_pHandler == NULL)
        {
            cout<<"PM said:OK, it's Over!"<<endl;
            return true;
        }
        else
        {
            cout<<"PM said:OK, transfer to next Manager."<<endl;
            return m_pHandler->HandleRequest(pRequest);
        }
    }

    // Department manager
    //////////////////////////////////////////////////////////////////////////
    DM::DM(Manager *handler)
        : m_pHandler(handler)
    {}
    
    DM::~DM()
    {}
    
    bool DM::HandleRequest(HolidayRequest *pRequest)
    {
        cout<<"DM said:OK, it's Over!"<<endl;
        return true;
    }

    // The department manager is in?
    bool DM::IsIn()
    {
        return true;
    }

    // Project supervisor
    //////////////////////////////////////////////////////////////////////////
    PS::PS(Manager *handler)
        : m_pHandler(handler)
    {}

    PS::~PS()
    {}

    bool PS::HandleRequest(HolidayRequest *pRequest)
    {
        DM *pDM = dynamic_cast<DM *>(m_pHandler);
        if (pDM != NULL)
        {
            if (pDM->IsIn())
            {
                return pDM->HandleRequest(pRequest);
            }
        }

        cout<<"PS said:OK, it's Over!"<<endl;
        return true;
    }

    //////////////////////////////////////////////////////////////////////////
    void ChainOfResponsibilityPattern_Test()
    {
        DM *pDM = new DM(NULL);
        PS *pPS = new PS(pDM);
        PM *pPM = new PM(pPS);
        HolidayRequest *pHolidayRequest = new HolidayRequest(10);
        pPM->HandleRequest(pHolidayRequest);
        SAFE_DELETE(pHolidayRequest);

        pHolidayRequest = new HolidayRequest(2);
        pPM->HandleRequest(pHolidayRequest);

        SAFE_DELETE(pDM);
        SAFE_DELETE(pPS);
        SAFE_DELETE(pPM);
        SAFE_DELETE(pHolidayRequest);
    }
}

客户端

#include "ChainOfResponsibilityPattern.h"


#include <iostream>
using namespace std;
using namespace ChainOfResponsibilityPattern;
void main()
{
    ChainOfResponsibilityPattern_Test();
}

PM said:OK,transfer to next Manager.
DM said:OK,it's Over!
PM said:OK,it's Over!