设计模式-结构型-代理

#pragma once#ifndef PROXY_H #define PROXY_H // 定义了Proxy 和RealSubject 的公有接口, // 这样就可以在任何需要使用到RealSubject 的地方都使用Proxy. class Subject { public: Subject(){} virtual ~Subject(){} virtual void Request() = 0; }; // 真正使用的实体 class RealSubject : public Subject { public: RealSubject(); virtual ~RealSubject(){} virtual void Request(); }; // 代理类,含有一个指向RealSubject 对象的指针 class Proxy : public Subject { public: Proxy();virtual ~Proxy(); virtual void Request(); private: RealSubject* m_pRealSubject; }; #endif 

#include "StdAfx.h"#include "proxy_impl.h"#include <iostream> RealSubject::RealSubject() { std::cout << "Constructing a RealSubject\n"; } void RealSubject::Request() { std::cout << "Request By RealSubject\n"; } Proxy::Proxy() : m_pRealSubject(NULL) { std::cout << "Constructing a Proxy\n"; } Proxy::~Proxy() { delete m_pRealSubject; m_pRealSubject = NULL;} void Proxy::Request() { // 需要使用RealSubject 的时候才去初始化 if (NULL == m_pRealSubject) { std::cout << "Request By Proxy\n"; m_pRealSubject = new RealSubject(); } m_pRealSubject->Request(); } 

// Proxy.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "proxy_impl.h"#include <stdlib.h>//为其他对象提供一种代理以控制对这个对象的访问。int _tmain(int argc, _TCHAR* argv[]){Subject* pProxy = new Proxy(); pProxy->Request(); delete pProxy; system("pause"); return 0;}