public interface Subject {    public void registerObserver(Observer o);    public void removeObserver(Observer o);    public void notifyObservers();}

package com.fen.dou.sjms.observer;import java.util.ArrayList;/** *类是核心 *1. 包含最新的天气情况信息 *2. 含有 观察者集合，使用 ArrayList 管理 *3.  当数据有更新时，就主动的调用	ArrayList, 通知所有的（接入方）就看到最新的信息 *@author Administrator * */public class WeatherData implements Subject {    private float temperatrue;    private float pressure;    private float humidity;    //观察者集合    private ArrayList
    
      observers;//加入新的第三方    public WeatherData() {       observers =new ArrayList
     
      ();    }    public float getTemperature() {        return temperatrue;    }    public float getPressure() {        return pressure;    }    public float getHumidity() {        return humidity;    }    public void dataChange() {        //调用 接入方的 update        notifyObservers();    }    //当数据有更新时，就调用 setData    public void setData(float temperature, float pressure, float humidity) { this.temperatrue = temperature;        this.pressure = pressure; this.humidity = humidity;         //调用 dataChange， 将最新的信息 推送给 接入方 currentConditions        dataChange();    }    //注册一个观察者 @Override    public void registerObserver(Observer o) {       // TODO Auto-generated method stub        observers.add(o);    }    //移除一个观察者 @Override    public void removeObserver(Observer o) {// TODO Auto-generated method stub if(observers.contains(o)) {        observers.remove(o);    }    //遍历所有的观察者，并通知 @Override    public void notifyObservers() {// TODO Auto-generated method stub        for(int i = 0; i < observers.size(); i++) {            observers.get(i).update(this.temperatrue, this.pressure, this.humidity);        }    }}
     
    

package com.fen.dou.sjms.observer;//观察者接口，有观察者来实现public interface Observer {    public void update(float temperature, float pressure, float humidity);}

package com.fen.dou.sjms.observer;public class BaiduSite implements Observer {    // 温度，气压，湿度      private float temperature;      private float pressure;      private float humidity;    //  更新  天气情况，是由  WeatherData  来调用，我使用推送模式    public void update(float temperature, float pressure, float humidity) {        this.temperature = temperature;        this.pressure = pressure;        this.humidity = humidity; display();    }    // 显 示    public void display() {        System.out.println("===百度网站====");        System.out.println("***百度网站 气温 : " + temperature + "***");        System.out.println("***百度网站 气压: " + pressure + "***");        System.out.println("***百度网站 湿度: " + humidity + "***");    }}

package com.fen.dou.sjms.observer;public class CurrentConditions implements Observer {    // 温度，气压，湿度    private float temperature;    private float pressure;    private float humidity;    // 更新 天气情况，是由 WeatherData 来调用，我使用推送模式    public void update(float temperature, float pressure, float humidity) { this.temperature = temperature;        this.pressure = pressure; this.humidity = humidity; display();    }    // 显 示    public void display() {        System.out.println("***Today mTemperature: " + temperature + "***");        System.out.println("***Today mPressure: " + pressure + "***");        System.out.println("***Today mHumidity: " + humidity + "***");    }}

package com.fen.dou.sjms.observer;public class Client {    public static void main(String[] args) {         // TODO Auto-generated method stub        //创建一个 WeatherData        WeatherData weatherData = new WeatherData();        //创建观察者        CurrentConditions currentConditions = new CurrentConditions();        BaiduSite baiduSite = new BaiduSite();        // 注 册 到 weatherData        weatherData.registerObserver(currentConditions);        weatherData.registerObserver(baiduSite);        // 测 试        System.out.println("通知各个注册的观察者, 看看信息");        weatherData.setData(10f, 100f, 30.3f);        weatherData.removeObserver(currentConditions);        //测试System.out.println();        System.out.println("通知各个注册的观察者, 看看信息");        weatherData.setData(10f, 100f, 30.3f);    }}

 org.springframework.context.ApplicationListener中的使用

public class MyEvent extends ApplicationContextEvent {    public MyEvent(ApplicationContext source) {        super(source);    }    public void out(String name)    {        System.out.println("MyEvent 事件执行了 name :"+name);    }}

import org.springframework.context.ApplicationListener;public class MyListenerA implements ApplicationListener
    
      {    @Override    public void onApplicationEvent(MyEvent event) {        System.out.println("MyListenerA 执行了");        event.out("wangmingyuan not love");    }}
    

import org.springframework.context.ApplicationListener;public class MyListenerB implements ApplicationListener
    
      {    @Override    public void onApplicationEvent(MyEvent event) {        System.out.println("MyListenerB 执行了");        event.out("wangmingyuan not love");    }}
    

public class MyPublisher implements ApplicationContextAware {    public ApplicationContext applicationContext;    @Override    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        this.applicationContext=applicationContext;    }    public void publisherEvent(ApplicationEvent event)    {        System.out.println("-----发送事件-----"+event);        applicationContext.publishEvent(event);    }}

@Import(value = {MyEvent.class,MyListenerA.class,MyListenerB.class,MyPublisher.class})public class EventTest {    public static void main(String[] args) {        AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext(EventTest.class);        MyPublisher myPublisher = context.getBean(MyPublisher.class);        MyEvent myEvent = context.getBean(MyEvent.class);        myPublisher.publisherEvent(myEvent);    }}