1 #include<iostream>
  2 #include<list>
  3 #include<string>
  4 using namespace std;
  5 
  6 class Subject;
  7 
  8 class Observer{     //观察者抽象类
  9     protected:
 10     string name;    //观察者自己的名字
 11     Subject* sub;   //观察的对象
 12     
 13     public:
 14     Observer(const string&,Subject*);
 15     virtual void Update()=0;
 16 };
 17 
 18 class StockObserver:public Observer{    //炒股的观察者类
 19     private:
 20 
 21     public:
 22     StockObserver(const string& _name,Subject* _sub):Observer(_name,_sub){} //委托Observer类的构造函数进行构造
 23     void Update();
 24 };
 25 
 26 class NbaObserver:public Observer{      //看NBA的观察者类
 27     private:
 28 
 29     public:
 30     NbaObserver(const string& _name,Subject* _sub):Observer(_name,_sub){} //委托Observer类的构造函数进行构造
 31     void Update();
 32 };
 33 
 34 
 35 class Subject{  //通知者抽象基类
 36     protected:
 37     list<Observer*> observerList;   //一个集合，存储所有观察本对象的观察者对象
 38 
 39     public:
 40     string status;      //本对象的状态
 41     virtual void attach(Observer*)=0;       //新增一个观察者
 42     virtual void detach(Observer*)=0;       //减少一个观察者
 43     virtual void Notify()=0;                //通知所有观察者
 44 };
 45 
 46 Observer::Observer(const string& _name,Subject* _sub):name(_name),sub(_sub){
 47     _sub->attach(this);
 48 }//构造函数
 49 
 50 void StockObserver::Update(){
 51     cout<<name<<" get information: "<<sub->status<<endl;
 52     cout<<"Close the stock and i‘m working!"<<endl<<endl;
 53 }
 54 
 55 void NbaObserver::Update(){
 56     cout<<name<<" get information: "<<sub->status<<endl;
 57     cout<<"Close the NBA and i‘m working!"<<endl<<endl;
 58 }
 59 
 60 class BossSubject:public Subject{  //老板通知者类
 61     private:
 62 
 63     public:
 64     BossSubject(){status="Boss come!";}
 65     void attach(Observer* _observer){
 66         observerList.push_back(_observer);
 67     }
 68     void detach(Observer* _observer){
 69         observerList.remove(_observer);
 70     }
 71     void Notify(){
 72         for(const auto& obs:observerList){
 73             obs->Update();
 74         }
 75     }
 76 };
 77 
 78 class SecretarySubject:public Subject{     //秘书通知者类
 79     private:
 80 
 81     public:
 82     SecretarySubject(){status="Secretary come!";}
 83     void attach(Observer* _observer){
 84         observerList.push_back(_observer);
 85     }
 86     void detach(Observer* _observer){
 87         observerList.remove(_observer);
 88     }
 89     void Notify(){
 90         for(const auto& obs:observerList){
 91             obs->Update();
 92         }
 93     }
 94 };
 95 
 96 int main(){
 97     BossSubject* boss=new BossSubject();    //老板
 98     SecretarySubject* secretary=new SecretarySubject();     //秘书
 99     StockObserver* stockA=new StockObserver("stockA",boss);
100     StockObserver* stockB=new StockObserver("stockB",boss);
101 
102 
103     NbaObserver* nba1=new NbaObserver("nba1",secretary);
104     NbaObserver* nba2=new NbaObserver("nba2",secretary);
105 
106     boss->Notify();
107     secretary->Notify();
108     cout<<"-------------------------------"<<endl;
109     cout<<"boss detach stockB and secretary detach nba1!"<<endl<<"-------------------------------"<<endl;
110     boss->detach(stockB);
111     secretary->detach(nba1);
112 
113     boss->Notify();
114     secretary->Notify();
115     getchar();
116 }