C++設(shè)計模式編程中proxy代理模式的使用實例
代理模式典型的結(jié)構(gòu)圖為:
實際上,代理模式的想法非常簡單。
代理模式的實現(xiàn):
完整代碼示例(code):代理模式的實現(xiàn)很簡單,這里為了方便初學(xué)者的學(xué)習(xí)和參考,將給出完整的實現(xiàn)代碼(所有代碼采用 C++實現(xiàn),并在 VC 6.0 下測試運行)。
代碼片斷 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_
代碼片斷 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(); }
代碼片斷 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; }
代碼說明:代理模式的實現(xiàn)很簡單,這里不做多余解釋??梢钥吹?,示例代碼運行后,p 的 Request 請求實際上是交給了 sub 來實際執(zhí)行。
再來看一個例子:
#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; }
由此可見,代理模式最大的好處就是實現(xiàn)了邏輯和實現(xiàn)的徹底解耦。
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