C++设计模式编程中的观察者模式使用示例

#include<vector>
#include<iostream>
#include<string>
using namespace std;
 
class Subject;
 
class Observer{          //观察者抽象类
public:
 virtual void update(Subject *base)=0;
protected:
 Subject * _subject;
};
 
class Subject{          //目标抽象类
public:
 string s1;            //数据值，可以作为私有数据，然后定义一个借口去返回值，这里为了省事
 int i1;               //数据值
 void regiObserver(Observer *obs){
  _observer.push_back(obs);
   cout<<"已注册"<<endl;
 }
 void deleObserver(Observer *obs){
  _observer.pop_back();
 }
 void notify(){        //更新所有的观察者
  vector<Observer *>::iterator it;
  for(it = _observer.begin(); it != _observer.end(); it++)
   (*it)->update(this);
 } 
private:
 vector<Observer *> _observer;    //观察者容器
};
 
class FSubject:public Subject{        
public:
 void set(string s,int i){
  s1 = s;
  i1 = i;
  notify();                  //通知观察者。主函数的执行顺序已经保证了所有的观察者都已经进入容器内
 }
};
 
class FObserver :public Observer{  //第一个观察者派生类
public:
 FObserver(Subject *base):Observer(){
  _subject = base;
  _subject->regiObserver(this);
 }
 void update(Subject *base){
  s1 = base->s1;
  i1 = base->i1;
  display();
 }
 void display(){
  cout<<"更新值,第一个\n"<<s1<<endl;
  cout<<i1<<endl;
 }
private:
 string s1;
 int i1;
};
 
class SObserver:public Observer{  //第二个观察者派生类
 public:
 SObserver(Subject * base){
  _subject = base;
  _subject->regiObserver(this);
 }
 void update(Subject *base){
  s1 = base->s1;
  i1 = base->i1;
  display();
 }
  void display(){
  cout<<"更新值,第二个\n"<<s1<<endl;
  cout<<i1<<endl;
 }
private:
 string s1;
 int i1;
};
 
int main()
{
 FSubject * sub = new FSubject;
 FObserver * one = new FObserver(sub);
 SObserver * two = new SObserver(sub);
 sub->set("ok",3);
 return 0;