Spring中提供一些Aware相關的接口，BeanFactoryAware、 ApplicationContextAware、ResourceLoaderAware、ServletContextAware等等，其中最常用到的是ApplicationContextAware。實現ApplicationContextAware的Bean，在Bean被初始后，將會被注入 ApplicationContext的實例。ApplicationContextAware提供了publishEvent()方法，實現Observer(觀察者)設計模式的事件傳播機，提供了針對Bean的事件傳播功能。通過Application.publishEvent方法，我們可以將事件通知系統內所有的ApplicationListener。

Spring事件處理一般過程：

·定義Event類，繼承org.springframework.context.ApplicationEvent.

·編寫發布事件類Publisher，實現org.springframework.context.ApplicationContextAware接口.

·覆蓋方法setApplicationContext(ApplicationContext applicationContext)和發布方法publish(Object obj)

·定義時間監聽類EventListener，實現ApplicationListener接口，實現方法onApplicationEvent(ApplicationEvent event).

java 代碼

import org.springframework.context.ApplicationEvent; /** * 定義事件信息 * @author new * */ public class MessageEvent extends ApplicationEvent { private String message; public void setMessage(String message){ this.message = message; } public String getMessage(){ return message; } public MessageEvent(Object source, String message) { super(source); this.message = message; // TODO Auto-generated constructor stub } private static final long serialVersionUID = 1L; }

java 代碼

import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.context.support.FileSystemXmlApplicationContext; public class Publisher implements ApplicationContextAware { private ApplicationContext context; @Override public void setApplicationContext(ApplicationContext arg0) throws BeansException { // TODO Auto-generated method stub this.context = arg0; } public void publish(String message){ context.publishEvent(new MessageEvent(this,message)); } public static void main(String[] args) { ApplicationContext ctx = new FileSystemXmlApplicationContext("src/applicationContext.xml"); Publisher pub = (Publisher) ctx.getBean("publisher"); pub.publish("Hello World!"); pub.publish("The quick brown fox jumped over the lazy dog"); } }

java 代碼

import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; public class MessageEventListener implements ApplicationListener { @Override public void onApplicationEvent(ApplicationEvent event) { // TODO Auto-generated method stub if(event instanceof MessageEvent){ MessageEvent msEvent = (MessageEvent)event; System.out.println("Received: " + msEvent.getMessage()); } } }

在運行期，ApplicationContext會自動在當前的所有Bean中尋找ApplicationListener接口的實現，并將其作為事件接收對象。當Application.publishEvent方法調用時，所有的ApplicationListener接口實現都會被激發，每個ApplicationListener可根據事件的類型判斷是否是自己需要處理的事件，如上面的ActionListener只處理ActionEvent事件。