Spring---ApplicationContext的事件机制
事件源：ApplicationContext。publishEvent()方法：用于主动触发容器事件。
事件：ApplicationEvent类,容器事件，必须由ApplicationContext发布。
事件监听器：ApplicationListener接口，可由容器中任何监听器Bean担任。onApplicationEvent(ApplicationEvent event)：每当容器内发生任何事件时，此方法都被触发
容器事件类需继承ApplicationEvent类，容器事件的监听器类需实现ApplicationListener接口。
下面给出一个例子
1.首先定义一个EmailEvent类，继承ApplicationEvent类
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，定义一个EmailNotifier类，实现ApplicationListener接口，并复写onApplicationEvent()方法
public class EmailNotifier implements ApplicationListener {
@Override
public void onApplicationEvent(ApplicationEvent applicationEvent) {
if (applicationEvent instanceof EmailEvent){
EmailEvent emailEvent = (EmailEvent) applicationEvent;
System.out.println("需要发送邮件的接收地址： " + emailEvent.getAddress());
System.out.println("需要发送邮件的邮件正文： " + emailEvent.getText());
}else {
System.out.println("容器本身的事件： " + applicationEvent);
}
}
}
3.将监听器配置在容器中
<bean class="org.spring.listener.EmailNotifier"/>
4.编写主程序main
public class SpringTest {
public static void main(String[] args){
ApplicationContext ctx = new ClassPathXmlApplicationContext("spring-config.xml");
// EmailEvent ele = new EmailEvent("hello","[email protected]","this is a test");
// ctx.publishEvent(ele);
}
}
程序到此结束，运行结果如下：
容器本身的事件： org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@b81eda8: startup date [Thu Dec 04 20:20:52 CST 2014]; root of context hierarchy]
若取消main中的注释，即，使用publishEvent()来触发事件，运行结果如下：
容器本身的事件： org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@b81eda8: startup date [Thu Dec 04 20:24:03 CST 2014]; root of context hierarchy] 需要发送邮件的接收地址： [email protected] 需要发送邮件的邮件正文： this is a test