Observer 模式

 1 /////////////Subject.h/////////////////////////////////////////////////////////////
 2 #pragma once 
 3 #include <string>
 4 #include <list>
 5 using namespace std;
 6 class Observer ;
 7 
 8 typedef string State ;
 9 class Subject
10 {
11 public:
12     virtual ~Subject();
13     virtual void Attach(Observer* obv);
14     virtual void Detach(Observer* obv);
15     virtual void Notify();
16     virtual void SetState(const State& st) = 0 ;
17     virtual State GetState() = 0 ;
18 protected:
19     Subject();
20 
21 private:
22     list<Observer*>* _Obvs ;
23 };
24 
25 class ConcreteSubject : public Subject
26 {
27 public:
28     ~ConcreteSubject();
29     ConcreteSubject();
30     State GetState();
31     void SetState(const State& st) ;
32 protected:
33 private:
34     State _st ;
35 };

 1 //////////////////Observer.h////////////////////////////////////////////////////////
 2 #pragma once
 3 #include <string>
 4 using namespace std;
 5 typedef string State ;
 6 class Subject ;
 7 
 8 class Observer
 9 {
10 public:
11     virtual ~Observer();
12     virtual void Update(Subject* sub) = 0  ;
13     virtual void PrintInfo() = 0;
14     State _st ;
15 protected:
16     Observer();
17     
18 private:
19 };
20 
21 
22 class ConcreteObserverA : public Observer 
23 {
24 public:
25     ~ConcreteObserverA();
26     ConcreteObserverA(Subject* sub);
27     virtual Subject* GetSubject();
28     void Update(Subject* sub);
29     void PrintInfo();
30 protected:
31 private:
32     Subject* _sub ;
33 };
34 
35 class ConcreteObserverB : public Observer 
36 {
37 public:
38     ~ConcreteObserverB();
39     ConcreteObserverB(Subject* sub);
40     virtual Subject* GetSubject();
41     void Update(Subject* sub);
42     void PrintInfo();
43 protected:
44 private:
45     Subject* _sub ;
46 };

 1 ////////////Subject.cpp//////////////////////////////////////////////////////////////
 2 #include "Subject.h"
 3 #include "Observer.h"
 4 #include <list>
 5 typedef string State ;
 6 
 7 
 8 Subject::Subject()
 9 {
10     _Obvs = new list<Observer*>();//在模板的使用之前一定要new
11 }
12 Subject::~Subject()
13 {
14 
15 }
16 
17 void Subject::Attach(Observer* obv)
18 {
19     _Obvs->push_front(obv);
20 }
21 void Subject::Detach(Observer* obv)
22 {
23     if (obv != NULL)
24     {
25         _Obvs->remove(obv);
26     }    
27 }
28 void Subject::Notify()
29 {
30     list<Observer*>::iterator it = _Obvs->begin();
31     for (;it != _Obvs->end(); it++)
32     {
33         (*it)->Update(this);
34     }
35 }
36 
37 ConcreteSubject::~ConcreteSubject()
38 {
39 
40 }
41 ConcreteSubject::ConcreteSubject()
42 {
43     _st = ‘\0‘;
44 }
45 State ConcreteSubject::GetState()
46 {
47     return _st ;
48 }
49 void ConcreteSubject::SetState(const State& st)
50 {
51     _st = st ;
52 }

 1 ////////////Observer.cpp//////////////////////////////////////////////////////////////
 2 #include "Observer.h"
 3 #include "Subject.h"
 4 #include <iostream>
 5 using namespace std ;
 6 Observer::Observer()
 7 {
 8     _st = ‘\0‘;
 9 }
10 Observer::~Observer()
11 {
12 
13 }
14 
15 ConcreteObserverA::ConcreteObserverA(Subject* sub)
16 {
17     _sub = sub ;
18     _sub->Attach(this);
19 }
20 ConcreteObserverA::~ConcreteObserverA()
21 {
22     _sub->Detach(this);
23     if (_sub != NULL)
24     {
25         delete _sub ;
26     }
27 }
28 
29 Subject* ConcreteObserverA::GetSubject()
30 {
31     return _sub ;
32 }
33  void ConcreteObserverA::PrintInfo()
34 {
35     cout<<"观察者A的到的通知："<<_sub->GetState()<<endl;
36 }
37 
38 void ConcreteObserverA::Update(Subject* sub)
39 {
40     _st = sub->GetState();
41     PrintInfo();
42 }
43 
44 
45 ConcreteObserverB::ConcreteObserverB(Subject* sub)
46 {
47     _sub = sub ;
48     _sub->Attach(this);
49 }
50 ConcreteObserverB::~ConcreteObserverB()
51 {
52     _sub->Detach(this);
53     if (_sub != NULL)
54     {
55         delete _sub;
56     }
57 }
58 Subject* ConcreteObserverB::GetSubject()
59 {
60     return _sub ;
61 }
62 
63 void ConcreteObserverB::PrintInfo()
64 {
65     cout<<"观察者B的到的通知："<<_sub->GetState()<<endl;
66 }
67 void ConcreteObserverB::Update(Subject* sub)
68 {
69     _st = sub->GetState();
70     PrintInfo();
71 }

 1 /////////////main.cpp/////////////////////////////////////////////////////////////
 2 #include "Subject.h"
 3 #include "Observer.h"
 4 #include <iostream>
 5 using namespace std;
 6 
 7 int main()
 8 {
 9     Subject* sub = new ConcreteSubject();
10     Observer* o1 = new ConcreteObserverA(sub);
11     Observer* o2 = new ConcreteObserverB(sub);
12     
13     sub->SetState("你获得一封邮件！");
14     sub->Notify();
15     sub->SetState("你的评论有新的回复！");
16     sub->Notify();
17 
18 
19     getchar();
20     return 0 ;
21 }