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C++设计模式编程中proxy代理模式的使用实例

2020-05-23 14:08:09
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这篇文章主要介绍了C++设计模式编程中proxy代理模式的使用实例解析,代理模式可以被归类为结构型的设计模式,代理模式主张为对象提供一种代理以控制对这个对象的访问,需要的朋友可以参考下
 

代理模式典型的结构图为:

C++,设计模式编程,proxy代理模式

实际上,代理模式的想法非常简单。

代理模式的实现:

完整代码示例(code):代理模式的实现很简单,这里为了方便初学者的学习和参考,将给出完整的实现代码(所有代码采用 C++实现,并在 VC 6.0 下测试运行)。

代码片断 1:Proxy.h

//Proxy.h#ifndef _PROXY_H_#define _PROXY_H_class Subject{  public:  virtual ~Subject();  virtual void Request() = 0;  protected:  Subject();  private:};class ConcreteSubject:public Subject{  public:  ConcreteSubject();  ~ConcreteSubject();  void Request();  protected:  private:};class Proxy{  public:  Proxy();  Proxy(Subject* sub);  ~Proxy();  void Request();  protected:  private:  Subject* _sub;};#endif //~_PROXY_H_

代码片断 2:Proxy.cpp

//Proxy.cpp#include "Proxy.h"#include <iostream>using namespace std;Subject::Subject(){}Subject::~Subject(){}ConcreteSubject::ConcreteSubject(){}ConcreteSubject::~ConcreteSubject(){}void ConcreteSubject::Request(){  cout<<"ConcreteSubject......request  ...."<<endl;}Proxy::Proxy(){}Proxy::Proxy(Subject* sub){  _sub = sub;}Proxy::~Proxy(){  delete _sub;}void Proxy::Request(){  cout<<"Proxy request...."<<endl;  _sub->Request();}

代码片断 3:main.cpp

//main.cpp#include "Proxy.h"#include <iostream>using namespace std;int main(int argc,char* argv[]){   Subject* sub = new ConcreteSubject();  Proxy* p = new Proxy(sub);  p->Request();  return 0;}

代码说明:代理模式的实现很简单,这里不做多余解释。可以看到,示例代码运行后,p 的 Request 请求实际上是交给了 sub 来实际执行。

再来看一个例子:

#include <iostream> #include <string> using namespace std;  class Receiver { private:   string name;  public:   Receiver(string name):name(name)   {    }   string GetName()   {     return name;   } };  class Subject { public:   virtual void display(){} };  class Sender:public Subject {   Receiver *someone; public:   void SetReceiver(Receiver *someone)   {     this->someone = someone;   }   virtual void display()   {     cout<<"i hate you:" << someone->GetName()<<endl;   } };  class Proxy:public Subject { public:   Subject *realobject;    void SetClient(Subject *client)   {     this->realobject = client;   }    void display()   {     realobject->display();   } };  int main() {   Receiver *recv = new Receiver("nobody");   Sender *obj  = new Sender;   obj->SetReceiver(recv);   Proxy *proxy = new Proxy;   proxy->SetClient(obj);    proxy->display();    system("pause");   return 0; } 

由此可见,代理模式最大的好处就是实现了逻辑和实现的彻底解耦。



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