Chain Of Resoponsibility(職責鏈模式)

#ifndef HANDLER_H#define HANDLER_H#include <windows.h>class Handler{    public:        /** Default constructor */        Handler(Handler* pHandler);        /** Default destructor */        virtual ~Handler();        virtual void HandleRequest()=0;        BOOL HaveSuccessor(){return NULL!=m_pSuccessor;}    protected:    private:    Handler* m_pSuccessor;};#endif // HANDLER_H

#include "Handler.h"#include <windows.h>Handler::Handler(Handler* pHandler):m_pSuccessor(NULL){    m_pSuccessor=pHandler;}Handler::~Handler(){    //dtor}void Handler::HandleRequest(){    if (NULL!=m_pSuccessor)    {        m_pSuccessor->HandleRequest();    }}

#ifndef CONCRETEHANDLERA_H#define CONCRETEHANDLERA_H#include "Handler.h"class ConcreteHandlerA : public Handler{    public:        /** Default constructor */        ConcreteHandlerA(Handler* pHandler);        /** Default destructor */        virtual ~ConcreteHandlerA();        void HandleRequest();    protected:    private:};#endif // CONCRETEHANDLERA_H

#include "ConcreteHandlerA.h"#include <iostream>using namespace std;ConcreteHandlerA::ConcreteHandlerA(Handler* pHandler):Handler(pHandler){    //ctor}ConcreteHandlerA::~ConcreteHandlerA(){    //dtor}void ConcreteHandlerA::HandleRequest(){    if (HaveSuccessor())    {        Handler::HandleRequest();    }    else        cout<<"ConcreteHandlerA Handled Request"<<endl;}

#ifndef CONCRETEHANDLERB_H#define CONCRETEHANDLERB_H#include "Handler.h"class ConcreteHandlerB : public Handler{    public:        /** Default constructor */        ConcreteHandlerB(Handler* pHandler);        /** Default destructor */        virtual ~ConcreteHandlerB();        void HandleRequest();    protected:    private:};#endif // CONCRETEHANDLERB_H

#include "ConcreteHandlerB.h"#include <iostream>using namespace std;ConcreteHandlerB::ConcreteHandlerB(Handler* pHandler):Handler(pHandler){    //ctor}ConcreteHandlerB::~ConcreteHandlerB(){    //dtor}void ConcreteHandlerB::HandleRequest(){     if (HaveSuccessor())    {        Handler::HandleRequest();    }    else        cout<<"ConcreteHandlerB Handled Request"<<endl;}

#include <iostream>#include "Handler.h"#include "ConcreteHandlerA.h"#include "ConcreteHandlerB.h"using namespace std;int main(){    Handler* pHandlerA=new ConcreteHandlerA(NULL);    Handler* pHandlerB=new ConcreteHandlerB(pHandlerA);    pHandlerB->HandleRequest();    delete pHandlerB;    delete pHandlerA;    return 0;}