设计模式-行为-职责链

#pragma once

#ifndef CHAINOFRESPONSIBILITY_H 

#define CHAINOFRESPONSIBILITY_H 

#include <stdio.h> 

// 抽象基类,定义一个处理请求的接口 
class Handler 
{ 
public: 
  Handler(Handler *pSuccessor = NULL); 
  virtual ~Handler(); 

  // 纯虚函数,由派生类实现 
  virtual void HandleRequest() = 0; 

protected: 
  Handler* m_pNextHandler; //if pNextHandler is null,handler it itself
}; 

class ConcreateHandler1 : public Handler 
{ 
public: 
  ConcreateHandler1(Handler *pNextHandler = NULL) 
    : Handler(pNextHandler){} 
  virtual ~ConcreateHandler1(){} 
  virtual void HandleRequest(); 
}; 

class ConcreateHandler2 : public Handler 
{ 
public: 
  ConcreateHandler2(Handler *pNextHandler = NULL) 
    : Handler(pNextHandler){} 
  virtual ~ConcreateHandler2(){} 
  virtual void HandleRequest(); 
}; 

#endif

#include "StdAfx.h"
#include "chainofresponsibility_impl.h"

#include <iostream> 

Handler::Handler(Handler *pNextHandler /* = NULL*/) 
: m_pNextHandler(pNextHandler) 
{ 
} 

Handler::~Handler() 
{ 
  delete m_pNextHandler; 
  m_pNextHandler = NULL; 
} 

void ConcreateHandler1::HandleRequest() 
{ 
  if (m_pNextHandler) 
  { 
    std::cout <<"HandleRequest not by ConcreateHandler1,Transfer Next\n";
    m_pNextHandler->HandleRequest(); 
  } 
  else 
  { 
    std::cout << "HandleRequest by ConcreateHandler1\n"; 
  } 
}

void ConcreateHandler2::HandleRequest() 
{ 
  if (m_pNextHandler) 
  { 
    std::cout <<"HandleRequest not by ConcreateHandler2,Transfer Next\n";
    m_pNextHandler->HandleRequest(); 
  } 
  else 
  { 
    std::cout << "HandleRequest by ConcreateHandler2\n"; 
  } 
}

// ChainOfResponsibility.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include "chainofresponsibility_impl.h"
#include <stdlib.h>
//使多个对象都有机会处理请求,从而避免请求的发送者和接收者之间的耦合关系. 
//将这些对象连成一条链，并沿着这条链传递该请求,直到有一个对象处理它为止. 
int _tmain(int argc, _TCHAR* argv[])
{
  // p2::handlerequest-->p1::handlerequest
  Handler *p1 = new ConcreateHandler1(/*pNextHandler*/); 
  Handler *p2 = new ConcreateHandler2(p1); 

  p2->HandleRequest(); 

  delete p2; 
  system("pause");
  return 0;
}