Spring学习历程--- 一个监听器实例

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MailSendEvent.java

import org.springframework.context.ApplicationContext;import org.springframework.context.event.ApplicationContextEvent;public class MailSendEvent extends ApplicationContextEvent {private String to;public MailSendEvent(ApplicationContext source, String to) {super(source);this.to = to;}public String getTo() {return this.to;}}

MailSendListener.java

import org.springframework.context.ApplicationListener;public class MailSendListener implements ApplicationListener<MailSendEvent>{public void onApplicationEvent(MailSendEvent event) {MailSendEvent mse = (MailSendEvent) event;System.out.println("MailSendListener:向" + mse.getTo() + "发送完一封邮件");}}

MailSender.java

public class MailSender implements ApplicationContextAware {private ApplicationContext ctx ;public void setApplicationContext(ApplicationContext ctx)throws BeansException {this.ctx = ctx;}public void sendMail(String to){System.out.println("MailSender:模拟发送邮件...");MailSendEvent mse = new MailSendEvent(this.ctx,to);ctx.publishEvent(mse);}}

beans.xml

<?xml version="1.0" encoding="UTF-8" ?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">     <bean class="com.baobaotao.event.MailSendListener"/>     <bean id="mailSender" class="com.baobaotao.event.MailSender"/></beans>

ApplicationEventTest.java

import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class ApplicatonEventTest {public static void main(String[] args) {String resourceFile = "com/baobaotao/event/beans.xml";ApplicationContext ctx = new ClassPathXmlApplicationContext(resourceFile);MailSender mailSender = ctx.getBean(MailSender.class);mailSender.sendMail("test mail.");    System.out.println("done.");}}

首先由sendMail方法产生一个MailSendEvent , 并把这个事件发送给所有事件监听器。

MailSendListener类继承了事件监听器接口ApplicationListener，处理了这个事件。

其中

public void onApplicationEvent(MailSendEvent event) {MailSendEvent mse = (MailSendEvent) event;System.out.println("MailSendListener:向" + mse.getTo() + "发送完一封邮件");}

这个方法就是处理事件的方法。

Spring只有两个事件监听器接口

1.ApplicaionListener , 只有一个方法

onApplicationEvent(E event) , 该方法接受ApplicationEvent 事件对象，在该方法中编写事件的响应处理逻辑。

2.SmartApplicationListener接口，有两个方法：

1）boolean supportsEventType(Class<? extends ApplicationEvent>eventType) : 指定监听器支持哪种类型的容器事件，即他只会对该类型的事件做出响应。

2）boolean supportsSourceType(Class<?> sourceType) : 该方法指定监听器仅对何种事件源对象做出响应。

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