c++ 行为型模式-责任链(Chain of Responsibility)

 1 #include <iostream>
 2 #include <list>
 3 class  Handler
 4 {
 5 public:
 6     Handler(Handler* successor):m_successor(successor){}
 7     virtual ~Handler() 
 8     {
 9         if (m_successor)
10         {
11             delete m_successor;
12             m_successor = NULL;
13         }
14     }
15     virtual void  HandleRequest(int num) = 0;
16 protected:
17     Handler* m_successor;
18 };
19 class  ConcreateHandler1 : public Handler
20 {
21 public:
22     ConcreateHandler1(Handler* successor) :Handler(successor) {}
23     virtual ~ConcreateHandler1() {}
24     virtual void  HandleRequest(int num)
25     {
26         if (num == 1)
27         {
28             std::cout << "ConcreateHandler1 HandleRequest" << std::endl;
29         }
30         else if (m_successor != NULL)
31         {
32             m_successor->HandleRequest(num);
33         }
34         else
35         {
36             std::cout << "error ConcreateHandler1 m_successor null" << std::endl;
37 
38         }
39     }
40 };
41 class  ConcreateHandler2 : public Handler
42 {
43 public:
44     ConcreateHandler2(Handler* successor) :Handler(successor) {}
45     virtual ~ConcreateHandler2() {}
46     virtual void  HandleRequest(int num)
47     {
48         if (num == 2)
49         {
50             std::cout << "ConcreateHandler2 HandleRequest" << std::endl;
51         }
52         else if (m_successor != NULL)
53         {
54             m_successor->HandleRequest(num);
55         }
56         else
57         {
58             std::cout << "error ConcreateHandler1 m_successor null" << std::endl;
59 
60         }
61     }
62 };
63 
64  int main()
65  {
66      Handler* ptr1 = new ConcreateHandler1(NULL);
67      Handler* ptr2 = new ConcreateHandler2(ptr1);
68      ptr2->HandleRequest(1);
69      ptr2->HandleRequest(2);
70      ptr2->HandleRequest(0);
71 
72      delete ptr2;
73      system("pause");
74  }