在Spring中有这样一种情景就是，我只想监听我想要的那个事件其他的我不需要。OK，在Spring中确实可以实现这种需求，先看看怎样监听的
package com.yohanliyanage.blog.springevents; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; public class MyEventListener implements ApplicationListener { private static final Log LOG = LogFactory.getLog(MyEventListener.class); public void onApplicationEvent(ApplicationEvent event) { LOG.info("Event Occurred : " + event); } } < ?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- Adding the listener class to Spring Container automatically registers it for events --> <bean class="com.yohanliyanage.blog.springevents.MyEventListener" /> </beans>好了这样的话
public class Main { public static void main(String[] args) throws InterruptedException { ApplicationContext context = new ClassPathXmlApplicationContext("classpath:META-INF/spring/application-context.xml"); } } 18:45:00 INFO Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7a982589: startup date [Sun Sep 30 18:45:00 IST 2012]; root of context hierarchy 18:45:00 INFO Loading XML bean definitions from class path resource [META-INF/spring/application-context.xml] 18:45:00 INFO Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@33e228bc: defining beans [com.yohanliyanage.blog.springevents.MyEventListener#0]; root of factory hierarchy 18:45:00 INFO Event Occurred : org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@7a982589: startup date [Sun Sep 30 18:45:00 IST 2012]; root of context hierarchy]怎样实现自己的Event的呢？
package com.yohanliyanage.blog.springevents; import org.springframework.context.ApplicationEvent; public class MyCustomEvent extends ApplicationEvent { private static final long serialVersionUID = -5308299518665062983L; public MyCustomEvent(Object source) { super(source); } }那怎样发布事件呢？
package com.yohanliyanage.blog.springevents; import org.springframework.context.ApplicationEventPublisher; import org.springframework.context.ApplicationEventPublisherAware; public class MyEventPublisher implements ApplicationEventPublisherAware { private ApplicationEventPublisher publisher; public void setApplicationEventPublisher(ApplicationEventPublisher publisher) { this.publisher = publisher; } public void publish() { this.publisher.publishEvent(new MyCustomEvent(this)); } } <bean class="com.yohanliyanage.blog.springevents.MyEventPublisher" /> public static void main(String[] args) throws InterruptedException { ApplicationContext context = new ClassPathXmlApplicationContext("classpath:META-INF/spring/application-context.xml"); MyEventPublisher publisher = context.getBean(MyEventPublisher.class); publisher.publish(); }那么还按上面ApplicationEventListener的话输出是这样的
19:21:18 INFO Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7a982589: startup date [Sun Sep 30 19:21:18 IST 2012]; root of context hierarchy 19:21:18 INFO Loading XML bean definitions from class path resource [META-INF/spring/application-context.xml] 19:21:19 INFO Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@2565a3c2: defining beans [com.yohanliyanage.blog.springevents.MyEventListener#0,com.yohanliyanage.blog.springevents.MyEventPublisher#0]; root of factory hierarchy 19:21:19 INFO Event Occurred : org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@7a982589: startup date [Sun Sep 30 19:21:18 IST 2012]; root of context hierarchy] 19:21:19 INFO Event Occurred : com.yohanliyanage.blog.springevents.MyCustomEvent[source=com.yohanliyanage.blog.springevents.MyEventPublisher@5a676437]现在只想监听我自己定制的ApplicationEvent，，3.0以后
package com.yohanliyanage.blog.springevents; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.context.ApplicationListener; public class MyEventListener implements ApplicationListener < MyCustomEvent > { private static final Log LOG = LogFactory.getLog(MyEventListener.class); public void onApplicationEvent(MyCustomEvent event) { LOG.info("Event Occurred : " + event); } }打印如下 19:29:31 INFO Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7a982589: startup date [Sun Sep 30 19:29:31 IST 2012]; root of context hierarchy 19:29:31 INFO Loading XML bean definitions from class path resource [META-INF/spring/application-context.xml] 19:29:31 INFO Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@2565a3c2: defining beans [com.yohanliyanage.blog.springevents.MyEventListener#0,com.yohanliyanage.blog.springevents.MyEventPublisher#0]; root of factory hierarchy 19:29:31 INFO Event Occurred : com.yohanliyanage.blog.springevents.MyCustomEvent[source=com.yohanliyanage.blog.springevents.MyEventPublisher@5a676437]上面说的都是同步的操作，还有异步的 ApplicationEventMulticaster可以用于TaskExecutor
在spring中EventListener接口的源码
package java.util; /** * A tagging interface that all event listener interfaces must extend. * @since JDK1.1 */ public interface EventListener { } EventListener 解释说明了EventListener只是一个标记接口和Cloneable,Serializable没是什么区别，只是用来标记一下事件监听器的接口。
