设计模式-观察者模式

[实验任务]：股票提醒

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。

 

 

java代码

package experiment21;

public interface AbstractObserver {
    void response(int n);
}


package experiment21;

import java.util.ArrayList;


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

    
    public void up() {};
    public void down() {};
}


package experiment21;

public class Client {
    public static void main(String []args) {
        AbstractSubject as=new ConcreteSubject();
        
        AbstractObserver ao1=new ConcreteObserver("张三");
        AbstractObserver ao2=new ConcreteObserver("李四");
        AbstractObserver ao3=new ConcreteObserver("王五");
        AbstractObserver ao4=new ConcreteObserver("赵六");
        
        as.attach(ao1);
        as.attach(ao2);
        as.attach(ao3);
        as.attach(ao4);
        
        as.up();
        
        System.out.println("****************");
        
        as.down();
    }
}


package experiment21;

public class ConcreteObserver implements AbstractObserver{
    private String name;
    
    public ConcreteObserver(String name) {
        this.name=name;
    }
    
    @Override
    public void response(int n) {
        // TODO Auto-generated method stub
        if(n==1) {
            System.out.println(name+"  买入！");
        }else {
            System.out.println(name+"  大哭");
        }
    }
    
}


package experiment21;

import java.util.ArrayList;


public class ConcreteSubject extends AbstractSubject{

    
    @Override
    public void up() {
        // TODO Auto-generated method stub
        System.out.println("股票上涨");
        for(Object obs:observers)
        {
            ((ConcreteObserver)obs).response(1);
        }
    }

    @Override
    public void down() {
        // TODO Auto-generated method stub
        System.out.println("股票下跌");
        for(Object obs:observers)
        {
            ((ConcreteObserver)obs).response(0);
        }
    }

}

 

c++代码

#include <string>
#include <iostream>

#include <vector>
using namespace std;

class guancha
{
    virtual void sheng()=0;
    virtual void jiang()=0;
};
class gumin
{
private:
    string name;
public:
    gumin(string a)
    {
        name=a;
    }
    void sheng()
    {
        cout<<name<<"买了一些股票（股票升了）"<<endl;
    }
    void jiang()
    {
        cout<<name<<"买了一些股票（股票降了）"<<endl;
    }
};
class fen
{
private:
    vector<gumin> obj;
public:
    fen()
    {}
    void add(gumin g)
    {
        obj.push_back(g);

    }
    void remove()
    {
        obj.pop_back();
    }


};
int main()

{
    gumin g1=gumin("第一个股民");
    gumin g2=gumin("第二个股民");
    fen f=fen();
    f.add(g1);
    f.add(g2);
    cout<<"股票升了"<<endl;
    cout<<"张三买入"<<endl;
    cout<<"股票降了"<<endl;
    cout<<"张三大哭"<<endl;
}