设计模式之观察者模式

package com.observer;

import java.util.ArrayList;
import java.util.List;


public class Subject {
    
    private int stat;
    
    private List oberverList= new ArrayList();;

    
    public void setStat(int stat) {
        this.stat = stat;
        notifyAllObservers();
    }

    public int getStat() {
        return stat;
    }

    
    public void add(Oberver oberver) {
        oberverList.add(oberver);
    }

    
    public void notifyAllObservers() {
        oberverList.forEach(oberver -> oberver.handel());
    }
}

package com.observer;


public abstract class Oberver {
    
    protected Subject subject;

    
    public abstract void handel();
}

package com.observer;


public class ObserverSon1 extends Oberver {

    
    public ObserverSon1(Subject subject) {
        this.subject = subject;
        this.subject.add(this);
    }

    @Override
    public void handel() {
        System.out.println("son1");
    }
}

package com.observer;


public class ObserverSon2 extends Oberver {

    
    public ObserverSon2(Subject subject) {
        this.subject = subject;
        this.subject.add(this);
    }

    @Override
    public void handel() {
        System.out.println("son2");
    }
}

package com.observer;


public class ObserverSon3 extends Oberver {

    
    public ObserverSon3(Subject subject) {
        this.subject = subject;
        this.subject.add(this);
    }

    @Override
    public void handel() {
        System.out.println("son3");
    }
}

package com.observer;


public class Main {

    public static void main(String[] args) {
        Subject subject = new Subject();
        new ObserverSon1(subject);
        new ObserverSon2(subject);
        new ObserverSon3(subject);
        subject.setStat(1);
    }
}

输出结果：