观察者模式

观察者

观察者模式定义了一种一队多的依赖关系，让多个观察者对象同时监听某一个主题对象。这个主题对象在状态上发生变化时，会通知所有观察者对象，使他们能够自动更新自己。
监视，观察者，都有一个基类，派生，实现不同的效果，监视者的类，管理所有的观察者，增加或者删除，发出消息，让观察者处理，观察者的类需要接受消息并处理

class Subject; //可以使用subjectclass Observer{protected:    string name;    Subject *sub;public:    Observer(string name, Subject *sub)//观察者的名字， 监视与通知的类    {        this->name = name;//输入名字        this->sub = sub;//设置谁来通知我    }    virtual void update() = 0;//纯虚函数};class StockObserver :public Observer //继承，自己实现刷新函数{public:    StockObserver(string name, Subject *sub) :Observer(name, sub)    {    }    void update();};class NBAObserver :public Observer{public:    NBAObserver(string name, Subject *sub) :Observer(name, sub)    {    }    void update();};class Subject  //{protected:    list<Observer*> observers;///存储观察者的指针，链表public:    string action;    virtual void attach(Observer*) = 0;    virtual void detach(Observer*) = 0;    virtual void notify() = 0;//实现监听的基类};class Secretary :public Subject   {    void attach(Observer *observer)  //载入通知的列表    {        observers.push_back(observer);    }    void detach(Observer *observer)//删除    {        list<Observer *>::iterator iter = observers.begin();        while (iter != observers.end())        {            if ((*iter) == observer)            {                observers.erase(iter);            }            ++iter;        }    }    void notify()  ///通知函数    {        list<Observer *>::iterator iter = observers.begin();        while (iter != observers.end())        {            (*iter)->update();            ++iter;        }    }};void StockObserver::update(){    cout << name << " 收到消息：" << sub->action << endl;    if (sub->action == "梁所长来了!")    {        cout << "我马上关闭股票，装做很认真工作的样子！" << endl;    }    if (sub->action == "去喝酒！")    {        cout << "我马上走" << endl;    }}void NBAObserver::update(){    cout << name << " 收到消息：" << sub->action << endl;    if (sub->action == "梁所长来了!")    {        cout << "我马上关闭NBA，装做很认真工作的样子！" << endl;    }   if (sub->action == "去喝酒！")   {    cout << "我马上拍" << endl;    }}int main123123(){    Subject *dwq = new Secretary();//消息监视，监视    Observer *xs = new NBAObserver("xiaoshuai", dwq);//订阅消息    Observer *zy = new NBAObserver("zouyue", dwq);    Observer *lm = new StockObserver("limin", dwq);    dwq->attach(xs);    dwq->attach(zy);    dwq->attach(lm);//增加到队列    dwq->action = "去吃饭了！";    dwq->notify();    dwq->action = "去喝酒！";    dwq->notify();    cout << endl;    dwq->action = "梁所长来了!";    dwq->notify();    cin.get();    return 0;}