观察者模式（observer）

一、代码示例

  1 #include <iostream>
  2 #include <vector>
  3 #include <string>
  4 using namespace std;
  5 
  6 ///抽象一个Subject主题
  7 ///观察者
  8 class Observer {
  9 public:
 10     virtual void update(string m_Temp, string m_Humi) = 0;
 11 protected:
 12     Observer() {}
 13 };
 14 class Subject {
 15 public:
 16     virtual void registerObserver(Observer* pObj)=0;
 17     virtual void removeObserver(Observer* pObj)=0;
 18     virtual void noitfyObserver()=0;
 19 protected:
 20     Subject(){}
 21 };
 22 
 23 class WeatherData :public Subject {
 24 public:
 25     WeatherData(string Temp, string Humi) : m_Temp(Temp), m_Humi(Humi) {
 26     }
 27     void registerObserver(Observer* pObj) {
 28         m_observers.push_back(pObj);
 29     }
 30     void removeObserver(Observer* pObj) {
 31         auto iter = find(m_observers.begin(), m_observers.end(), pObj);
 32         if (iter != m_observers.end()) {
 33             m_observers.erase(iter);
 34         }
 35     }
 36     void noitfyObserver() {
 37         //逐个遍历调用Observer的update方法
 38         for (vector<Observer*>::iterator iter = m_observers.begin();iter != m_observers.end();iter++) {
 39             (*iter)->update(m_Temp, m_Humi);
 40             
 41         }
 42     }
 43 
 44     void setData(string Temp, string Humi) {
 45         m_Temp = Temp;
 46         m_Humi = Humi;
 47         noitfyObserver();
 48     }
 49 private:
 50     vector<Observer*> m_observers;
 51     string m_Temp;//温度
 52     string m_Humi;//湿度
 53 };
 54 
 55 
 56 
 57 
 58 //CocreteObserver
 59 class PCDisplay:public Observer {
 60 public:
 61     void update(string m_Temp, string m_Humi) {
 62         cout << "我是PC端的显示GUI,当前的温度为" << m_Temp << "湿度为" << m_Humi << endl;
 63     }
 64 
 65     PCDisplay(WeatherData* pWeatherData) {
 66         m_pWeatherData = pWeatherData;
 67         m_pWeatherData->registerObserver(this);
 68     }
 69 private:
 70     WeatherData* m_pWeatherData;
 71 };
 72 
 73 
 74 
 75 class MobileDisplay :public Observer {
 76 public:
 77     void update(string m_Temp, string m_Humi) {
 78         cout << "我是Mobile端的显示GUI,当前的温度为" << m_Temp << "湿度为" << m_Humi << endl;
 79     }
 80 
 81     MobileDisplay(WeatherData* pWeatherData) {
 82         m_pWeatherData = pWeatherData;
 83         m_pWeatherData->registerObserver(this);
 84     }
 85 private:
 86     WeatherData* m_pWeatherData;
 87 };
 88 
 89 
 90 int main(void) {
 91     WeatherData* pWD = new WeatherData("22C", "65%");
 92     PCDisplay* pPCDisplay = new PCDisplay(pWD);
 93     MobileDisplay* pMobile = new MobileDisplay(pWD);
 94 
 95     pWD->setData("38C", "55%");
 96     pWD->removeObserver(pMobile);
 97     pWD->setData("31", "44%");
 98     
 99     system("pause");
100     return 0;
101 }