Java设计模式中观察者模式详解

/**
 * 观察者
 */
public interface Observer {
    /**
     * 更新
     */
    void update();
}
/**
 * 注意事项  被观察者  被观察者发出通知
 */
public abstract class Attentions {
    /**
     * 观察者列表
     */
    protected List<Observer> observers = new ArrayList();
    /**
     * 添加观察者
     * @param observer
     */
    public void add(Observer observer) {
        observers.add(observer);
    }
    /**
     * 取消关注
     * @param observer
     */
    public void remove(Observer observer) {
        observers.remove(observer);
    }
    /**
     * 被观察者发出通知 通知所有观察者  观察者可以做出相应的行为
     */
    public abstract void notifyObservers();
}
/**
 * 观察者  各种各样的观察者
 */
public class SoulMasterObserver implements Observer {
    private String name;
    public SoulMasterObserver(String name){
        this.name = name;
    }
    /**
     * 观察者接收到通知做一些事情
     */
    @Override
    public void update() {
        System.out.println(name + "收到作战通知，赶往嘉陵关");
    }
}
public class MangoAttention extends Attentions{
    @Override
    public void notifyObservers() {
        //遍历观察者集合
        for(Observer obs : observers) {
            obs.update();
        }
    }
    /*通知观察者*/
    public void perform(){
        this.notifyObservers();
    }
}
public class ObserverClient {
    public static void main(String[] args) {
        MangoAttention attentions = new MangoAttention();//目标
        attentions.add(new SoulMasterObserver("唐三"));
        attentions.add(new SoulMasterObserver("马红俊"));
        attentions.add(new SoulMasterObserver("小舞"));
        attentions.add(new SoulMasterObserver("宁荣荣"));
        attentions.perform();
    }
}

public class SoulMaster implements Observer {
    private String name;
    public SoulMaster(String name){
        this.name = name;
    }
    @Override
    public void update(Observable o, Object arg) {
        System.out.println(name + "收到作战通知，赶往嘉陵关");
    }
}
public class War extends Observable {
    private String name;
    public War(String name){
        this.name = name;
    }
    public void perform(){
        /*先设置改变*/
        this.setChanged();
        /*然后通知*/
        this.notifyObservers();
    }
}
public class JdkObserverClient {
    public static void main(String[] args) {
        War war = new War(":战争");
        war.addObserver(new SoulMaster("唐三"));
        war.addObserver(new SoulMaster("马红俊"));
        war.addObserver(new SoulMaster("小舞"));
        war.addObserver(new SoulMaster("宁荣荣"));
        war.perform();
    }
}