设计模式11---观察者模式

观察者模式实质就是提取：提取监听对象的过程是相同的，也就是说observer类为根据不同的subject的状态做出相应的反应。

package com.jayfulmath.designpattern.observer;



public abstract class Observer {

    

    protected String name;

    protected ISubject sub;    

    

    public Observer(String name, ISubject sub) {

        this.name = name;

        this.sub = sub;

    }

    public abstract void Update();

}

public interface ISubject {

    public void Attach(Observer obs);

    public void Detach(Observer obs);

    public void Broadcast();

    public String getSubjectStatus();

    public void setSubjectStatus(String subjectStatus);

}

public class NBALooker extends Observer {

    public NBALooker(String name, ISubject sub) {
        super(name, sub);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void Update() {
        System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop NBA Look");
    }

}

public class NBALooker extends Observer {



    public NBALooker(String name, ISubject sub) {

        super(name, sub);

        // TODO Auto-generated constructor stub

    }



    @Override

    public void Update() {

        System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop NBA Look");

    }



}

public class StockLooker extends Observer {



    public StockLooker(String name, ISubject sub) {

        super(name, sub);

        // TODO Auto-generated constructor stub

    }



    @Override

    public void Update() {

        // TODO Auto-generated method stub

        System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop Stock Look");

    }



}

import java.util.ArrayList;

import java.util.List;



public class Boss implements ISubject {

    

    List<Observer> _mObservers = new ArrayList<Observer>();    

    public String subjectStatus;

    

    public void Attach(Observer obs)

    {

        _mObservers.add(obs);

    }

    

    public void Detach(Observer obs)

    {

        _mObservers.remove(obs);

    }

    

    public void Broadcast()

    {

        //here may be asynchronous to notify observer

        for(Observer observer :_mObservers)

        {

            observer.Update();

        }

    }

    

    /**

     * @return the subjectStatus

     */

    public String getSubjectStatus() {

        return subjectStatus;

    }



    /**

     * @param subjectStatus the subjectStatus to set

     */

    public void setSubjectStatus(String subjectStatus) {

        this.subjectStatus = subjectStatus;

    }

}

main:

public class ObserverMain extends BasicExample {



    @Override

    public void startDemo() {

        ISubject huhanshang = new Boss();

        Observer maweidong = ObserverFactory.Factory("NBALooker", "maweidong", huhanshang);

        Observer zhangdashang = ObserverFactory.Factory("StockLooker", "zhangdashang", huhanshang);

        

        huhanshang.Attach(maweidong);

        huhanshang.Attach(zhangdashang);

        

        huhanshang.setSubjectStatus("I am back! Huhan Shang!");

        huhanshang.Broadcast();

    }



}