spring容器的事件机制

来源：互联网发布：百万公众网络答题2017 编辑：程序博客网时间：2024/06/07 06:47

spring容器的事件机制是通过观察者模式实现的。

spring容器的事件机制和所以的事件机制都类似，都是由事件源、事件、事件监听器组成，只不过这里的事件源是ApplicationContext（spring容器）。

spring容器的事件机制是有ApplicationEvent类和ApplicationListener接口实现的，如果容器有一个ApplicationListener Bean，当spring容器发布ApplicationEvent Bean时（初始化），ApplicationListener Bean将自动被调用。

例子：

1、EmailEent类继承ApplicationEvent类

package myspring.com.bean;import org.springframework.context.ApplicationEvent;public class EmailEvent extends ApplicationEvent {private String address;private String text;public EmailEvent(Object source){super(source);}public EmailEvent(Object source,String address,String text){super(source);this.address = address;this.text = text;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public String getText() {return text;}public void setText(String text) {this.text = text;}}

2、EmailNotifier类实现ApplicationListener接口

package myspring.com.bean;import org.springframework.context.ApplicationEvent;import org.springframework.context.ApplicationListener;public class EmailNotifier implements ApplicationListener {@Overridepublic void onApplicationEvent(ApplicationEvent arg0) {if(arg0 instanceof EmailEvent){EmailEvent e = (EmailEvent)arg0;System.out.println("邮件地址："+e.getAddress());System.out.println("邮件内容为："+e.getText());}else{System.out.println("该事件为容器内置事件"+arg0.toString());}}}

3、在bean.xml中配置监听器，和EmailEvent对象

<pre name="code" class="java"><bean class="myspring.com.bean.EmailNotifier"></bean>    <bean id = "emailEvent" class="myspring.com.bean.EmailEvent">  <constructor-arg value="hello"></constructor-arg>  <constructor-arg value="nannan22222@qq.com"></constructor-arg>  <constructor-arg value="spring event test"></constructor-arg>  </bean>

4、测试类

package myspring.com.bean;import org.springframework.context.ApplicationContext;import org.springframework.context.support.FileSystemXmlApplicationContext;public class EmailEventMainMethod {public static void main(String[] args) {// TODO Auto-generated method stubApplicationContext ac = new FileSystemXmlApplicationContext("config/bean.xml");//EmailEvent e = new EmailEvent("hello","nannan@qq.com","spring event test");EmailEvent e_ = ac.getBean("emailEvent",EmailEvent.class);//ac.publishEvent(e_);//监听spring容器内置事件}}

5、输出结果

邮件地址：nannan22222@qq.com邮件内容为：spring event test

---------------------------------------------------------------------------------

spring提供的几个其他内置事件：

1、ContextRefreashedEvent：spring容器初始化或者刷新触发该事件

2、ContextStartedEvent：ConfigurableApplicationContext（ApplicationContext的子接口）的start()方法启动spring容器时触发该事件

3、ContextClosedEvent：ConfigurableApplicationContext（ApplicationContext的子接口）的Close()方法关闭spring容器时触发该事件

4、ContextStopedEvent：ConfigurableApplicationContext（ApplicationContext的子接口）的stop()方法停止spring容器时触发该事件

5、RequstHandledEvent：使用spring作为MVC控制器时，spring处理用户请求结束后，触发该事件

0 0