c++ 结构型模式-代理(Proxy)

 1 #include <iostream>
 2 #include <list>
 3 class  Subject
 4 {
 5 public:
 6     Subject() {}
 7     virtual ~Subject() {}
 8     virtual void  Request() = 0;
 9 };
10 class  RealSubject : public Subject
11 {
12 public:
13     RealSubject() {}
14     virtual ~RealSubject() {}
15     virtual void  Request()
16     {
17         std::cout << "RealSubject request" << std::endl;
18     }
19 };
20 class Proxy : public Subject
21 {
22 public:
23     Proxy():m_object(NULL) {}
24     virtual ~Proxy() 
25     {
26         if (m_object)
27         {
28             delete m_object;
29         }
30     }
31     virtual void  Request()
32     {
33         if (m_object == NULL)
34         {
35             m_object = new RealSubject();
36         }
37         m_object->Request();
38     }
39 private:
40     RealSubject* m_object;
41 };
42 
43  int main()
44  {
45      Subject* subject = new Proxy();
46      subject->Request();
47      system("pause");
48  }