设计模式5——观察者模式

观察这模式中，有一个观察者监听一个事件，当事件发生时，向所有被通知者发送相应的消息和命令。

例如，秘书作为观察者，监听老板的动作。当老板回来时，向看电影、睡觉的员工发送消息，让他们停止并开始工作。

Observation.h内容

 1 #ifndef Observation_H_H
 2 #define Observation_H_H
 3 
 4 #include <iostream>
 5 #include <vector>
 6 using namespace std;
 7 
 8 class Secretary;
 9 
10 class Boss
11 {
12 public:
13     Boss();
14     void comeBack();
15     void setSecretary(Secretary *secretary0);
16 private:
17     Secretary *secretary;
18 };
19 
20 class Staff
21 {
22 public:
23     virtual void getSingal() = 0;
24     virtual ~Staff() {}
25 };
26 
27 class StaffMovie : public Staff
28 {
29 public:
30     virtual void getSingal() { cout << "Boss is coming, Stop watching movie!" << endl; }
31 };
32 
33 class StaffSleep : public Staff
34 {
35 public:
36     virtual void getSingal() { cout << "Boss is coming, Stop sleeping!" << endl; }
37 };
38 
39 class Secretary
40 {
41 public:
42     Secretary() : boss(NULL) {}
43     void sendSingal(){
44         for(size_t i=0; i<vecStaff.size(); ++i){
45             vecStaff[i]->getSingal();
46         }
47     }
48 
49     void addStaff(Staff *staff) { vecStaff.push_back(staff); }
50     void setBoss(Boss *boss0) { boss = boss0; }
51 private:
52     Boss *boss;
53     vector<Staff*> vecStaff;
54 };
55 
56 
57 Boss::Boss() : secretary(NULL) {}
58 void Boss::comeBack() { secretary->sendSingal(); }
59 void Boss::setSecretary(Secretary *secretary0) { secretary = secretary0; }
60 
61 void ObservationTest()
62 {
63     Boss *boss = new Boss();
64     Staff *staff1 = new StaffMovie();
65     Staff *staff2 = new StaffSleep();
66     Secretary *secretary = new Secretary();
67     secretary->addStaff(staff1);
68     secretary->addStaff(staff2);
69     secretary->setBoss(boss);
70     boss->setSecretary(secretary);
71 
72     boss->comeBack();
73 }
74 
75 #endif