Java/C++实现观察者模式--股票价格

当股票的价格上涨或下降5%时，会通知持有该股票的股民，当股民听到价格上涨的消息时会买股票，当价格下降时会大哭一场。

类图：

 

Java代码：

public class Investor implements MyObserver {

    @Override
    public void response1() {
        // TODO Auto-generated method stub
        System.out.println("股民买股票");
    }

    @Override
    public void response2() {
        // TODO Auto-generated method stub
        System.out.println("股民大哭一场");
    }
    
}


public interface MyObserver {
    void response1();
    void response2();
}


public class Stock extends Subject{

    @Override
    public void stockUp() {
        // TODO Auto-generated method stub
        System.out.println("股票上涨5%");
        for(Object obs:observers) {
            ((MyObserver)obs).response1();
        }
    }

    @Override
    public void stockDown() {
        // TODO Auto-generated method stub
        System.out.println("股票下降5%");
        for(Object obs:observers) {
            ((MyObserver)obs).response2();
        }
    }

}

import java.util.ArrayList;

public abstract class Subject {
    protected ArrayList observers=new ArrayList();
    //注册方法
    public void attach(MyObserver observer) {
        observers.add(observer);
    }
    //注销方法
    public void detach(MyObserver observer) {
        observers.remove(observer);
    }
    public abstract void stockUp();
    public abstract void stockDown();
}

public class Client {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Subject subject=new Stock();
        MyObserver obs1;
        obs1=new Investor();    
        subject.attach(obs1);
        subject.stockUp();
        subject.stockDown();
    }
}

C++代码：

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
class MyObserver
{
public:
    virtual void response1() = 0;
    virtual void response2() = 0;
};

class Investor:public MyObserver
{
public:
     void response1(){
        cout<<"股民买股票"<<endl;
    }
    void response2(){
        cout<<"股民大哭一场"<<endl;
    }
};
class Subject
{
public:
    Subject(){}
    virtual ~Subject(){}
    virtual void attach(MyObserver *observer)=0;
    virtual void detach(MyObserver *observer)=0;
    virtual void stockUp()=0;
    virtual void stockDown()=0;
};
class Stock:public Subject
{
public:
    void attach(MyObserver *observer)
    {
        observers.push_back(observer);
    }
    void detach(MyObserver *observer)
    {
        vector<MyObserver*>::iterator observer_rm = find(observers.begin(), observers.end(), observer);
        observers.erase(observer_rm);
    }
    void stockUp()
    {
         cout<<"股票上涨5%"<<endl;
         vector <MyObserver *>::iterator iObserver = observers.begin();
         while(iObserver != observers.end())
         {
              (*iObserver)->response1();
              iObserver++;
         }
    }
     void stockDown()
    {
         vector <MyObserver *>::iterator iObserver = observers.begin();
         cout<<"股票下降5%"<<endl;
         while(iObserver != observers.end())
         {
              (*iObserver)->response2();
              iObserver++;
         }
    }
private:
    vector<MyObserver*> observers;
};
int main()
{
    Stock subject;
    Investor obs;
    subject.attach(&obs);
    subject.stockUp();
    subject.stockDown();
}

运行结果：