【设计方式】为别人做嫁衣 - 代理模式

【设计模式】为别人做嫁衣 --- 代理模式

一，概述

        定义：代理模式（Proxy）为另一个对象提供一个替身或占位符以控制对这个对象的访问，简而言之就是用一个对象来代表另一个对象。

          作用：为其他对象提供一种代理以控制对这个对象的访问。在某些情况下，一个对象不想或者不能直接引用另一个对象，而代理对象可以在客户端和目标对象之间起到中介的作用。#include <iostream> class SchoolGirl //要追的女孩 {public:void SetName(std::string str)//名字 {m_Name = str;};std::string GetName(void) //获取女孩名字 {return m_Name;};private:std::string m_Name;};class Pursuit//追求行为类 {public:Pursuit(SchoolGirl* mm){m_mm = mm;};void GiveDolls(){std::cout << m_mm->GetName() << "送你洋娃娃" << std::endl;};void GiveFlower(){std::cout << m_mm->GetName() << "送你鲜花" << std::endl;};void GiveChocolate(){std::cout << m_mm->GetName() << "送你巧克力" << std::endl;};private:SchoolGirl* m_mm;};int main(){SchoolGirl* jiaojiao = new SchoolGirl();//初始化要追求的对象 jiaojiao->SetName("李娇娇");//事实上娇娇并不认识卓贾易Pursuit* zhuojiayi = new Pursuit(jiaojiao);zhuojiayi->GiveChocolate();zhuojiayi->GiveDolls();zhuojiayi->GiveFlower();delete jiaojiao;delete zhuojiayi;return 0;}

               2）小菜代理第二版

                  缺点：也不是让戴励自己亲自追求，不符合题意。

 

#include <iostream> class SchoolGirl //要追的女孩 {public:void SetName(std::string str)//名字 {m_Name = str;};std::string GetName(void) //获取女孩名字 {return m_Name;};private:std::string m_Name;};class Proxy//代理类，其实是戴励 {public:Proxy(SchoolGirl* mm){m_mm = mm;};void GiveDolls(){std::cout << m_mm->GetName() << "送你洋娃娃" << std::endl;};void GiveFlower(){std::cout << m_mm->GetName() << "送你鲜花" << std::endl;};void GiveChocolate(){std::cout << m_mm->GetName() << "送你巧克力" << std::endl;};private:SchoolGirl* m_mm;};int main(){SchoolGirl* jiaojiao = new SchoolGirl();jiaojiao->SetName("李娇娇");Proxy* daili = new Proxy(jiaojiao);daili->GiveChocolate();daili->GiveDolls();daili->GiveFlower();return 0;}

 

                   3）小菜第三版

                    改进：添加接口，让一个对象实现接口，代理负责运用接口。

                    实现：代理同样实现接口，只是代理实现接口的时候实际上是调用实际实现者的方法。

 

#include <iostream> class SchoolGirl //要追的女孩 {public:void SetName(std::string str)//名字 {m_Name = str;};std::string GetName(void) //获取女孩名字 {return m_Name;};private:std::string m_Name;};class GiveGift //送礼物接口（抽象函数就是接口） {virtual void GiveDolls(void) = 0;virtual void GiveFlower(void) = 0;virtual void GiveChocolate(void) = 0;};class Pursuit :public GiveGift//追求者去实现礼物接口{public:Pursuit(SchoolGirl* mm){m_mm = mm;};void GiveDolls(){std::cout << m_mm->GetName() << "送你洋娃娃" << std::endl;};void GiveFlower(){std::cout << m_mm->GetName() << "送你鲜花" << std::endl;};void GiveChocolate(){std::cout << m_mm->GetName() << "送你巧克力" << std::endl;};private:SchoolGirl* m_mm;};class Proxy :public GiveGift//代理类（也去实现送礼物接口，实际上是调用追求者的方法） {public:Proxy(SchoolGirl* mm){m_gg = new Pursuit(mm);};~Proxy(){if (m_gg != NULL){delete m_gg;m_gg = NULL;}};void GiveDolls(){m_gg->GiveDolls();};void GiveFlower(){m_gg->GiveFlower();};void GiveChocolate(){m_gg->GiveChocolate();};private:Pursuit* m_gg;};int main(){ SchoolGirl* jiaojiao = new SchoolGirl(); jiaojiao->SetName("李娇娇"); Proxy* daili = new Proxy(jiaojiao); daili->GiveChocolate(); daili->GiveDolls(); daili->GiveFlower(); return 0;}

 

三，代理模式的经典模板

 

     

class Subject{public:virtual void Request(void) = 0;};class RealSubject : public Subject{public:void Request(void){std::cout << "真实的请求" << std::endl;};};class Proxy : public Subject{public:Proxy():m_realSubject(NULL){}void Request(void){if (m_realSubject == NULL){m_realSubject = new RealSubject();}m_realSubject->Request();};private:RealSubject* m_realSubject;};int main(){Proxy* daili = new Proxy();daili->Request();delete daili;return 0;}

 

 

 

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