SpringMVC之ApplicationListener简单使用

摘要: 其实springmvc在启动的过程中，在很多地方都有event。ServletRequestHandledEvent就是其中一个，
在http请求的时候A...

#SpringMVC之ApplicationListener简单使用

个人感觉，最好的理解就是把虚拟的思维用现实中的模型实体化，如果找不到实体化的模型怎么办？那就自己创造模型。

我们用现实中的模型来实体化监听这个概念。

《疯狂的石头》里面的那个厕所的感应器就是监听器，手传过感应器就是一个事件，而手所属的人就是触发者。响铃就是监听器触发后做的事情。

废话多了，现在开始定义

手去摸传感器（event）

手(业务contrlller or sevice)

传感器(listener)

首先从厕所把那个感应器拆下来 TraderEvent
###手去摸传感器（event）

package com.excelib.publisher;

import org.springframework.context.ApplicationEvent;

public class TraderEvent extends ApplicationEvent {

/**
*
*/
private static final long serialVersionUID = 1L;

public TraderEvent(Object source) {
super(source);
// TODO Auto-generated constructor stub
System.out.println("--------响铃---------");
}

}

TraderEvent extends ApplicationEvent(spring) extends EventObject。(J2SE)

###手(业务contrlller or sevice)

package com.excelib.publisher;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.web.context.support.ServletRequestHandledEvent;

public class HelloWorld implements ApplicationEventPublisherAware {

@Autowired
private String word;

@Autowired
private ApplicationEventPublisher applicationEventPublisher;

public void say() {
System.out.println("say:" + word);
TraderEvent event = new TraderEvent(word);
this.applicationEventPublisher.publishEvent(event);
}

@Override
public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
// TODO Auto-generated method stub
this.applicationEventPublisher = applicationEventPublisher;
}

public String getWord() {
return word;
}

public void setWord(String word) {
this.word = word;
}

}

xxx-Aware不在介绍了。

###传感器(listener)

package com.excelib.publisher;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;

public class ApplicationContetxtListener implements ApplicationListener<ApplicationEvent> {

@Override
public void onApplicationEvent(ApplicationEvent event) {
// TODO Auto-generated method stub
System.out.println("ApplicationContetxtListener===" + event.getClass().toString());

if(event instanceof TraderEvent){
System.out.println("===ApplicationContetxtListener======TraderEvent");
System.out.println(event.toString());
}
else{
System.out.println("===ApplicationContetxtListener======OtherEvent");
System.out.println(event.toString());
}

}

}

###注入spring bean

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean name="helloWorld" class="com.excelib.publisher.HelloWorld">
<property name="word" value="hello world" />
</bean>

<bean id="applicationContetxtListener" class="com.excelib.publisher.ApplicationContetxtListener" />

</beans>

###Test类

package com.excelib.publisher;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestHelloWorld {

public static void main(String[] args) throws InterruptedException {
// TODO Auto-generated method stub

ApplicationContext ac = new ClassPathXmlApplicationContext("spring/spring-event.xml");

HelloWorld hw = (HelloWorld)ac.getBean("helloWorld");

hw.say();

}

}

一起就绪，run吧

ApplicationContetxtListener===class org.springframework.context.event.ContextRefreshedEvent
===ApplicationContetxtListener======OtherEvent
org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@443ad545: startup date [Fri Jun 16 18:21:18 CST 2017]; root of context hierarchy]
say:hello world
--------响铃---------
TraderContextListener:class com.excelib.publisher.TraderEvent
ApplicationContetxtListener===class com.excelib.publisher.TraderEvent
===ApplicationContetxtListener======TraderEvent
com.excelib.publisher.TraderEvent[source=hello world]

demo到此结束了。

##springmvc中的ServletRequestHandledEvent
其实springmvc在启动的过程中，在很多地方都设置了感应器。ServletRequestHandledEvent就是其中一个，
在http请求的时候，FrameworkServlet的doGet\doPost...里面会出发这个感应器。

protected final void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

processRequest(request, response);
}

protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

...
publishRequestHandledEvent(request, startTime, failureCause);

}

private void publishRequestHandledEvent(HttpServletRequest request, long startTime, Throwable failureCause) {
if (this.publishEvents) {
// Whether or not we succeeded, publish an event.
long processingTime = System.currentTimeMillis() - startTime;
this.webApplicationContext.publishEvent(
new ServletRequestHandledEvent(this,
request.getRequestURI(), request.getRemoteAddr(),
request.getMethod(), getServletConfig().getServletName(),
WebUtils.getSessionId(request), getUsernameForRequest(request),
processingTime, failureCause));
}
}

自定义 ApplicationContetxtListener 并注入到spring中

package com.xxx.listener;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.web.context.support.ServletRequestHandledEvent;

public class ApplicationContetxtListener implements ApplicationListener<ApplicationEvent> {

@Override
public void onApplicationEvent(ApplicationEvent event) {
// TODO Auto-generated method stub
System.out.println("ApplicationContetxtListener===" + event.getClass().toString());

if(event instanceof ServletRequestHandledEvent){
System.out.println("===ApplicationContetxtListener======ServletRequestHandledEvent");
System.out.println(event.toString());
}
else{
System.out.println("===ApplicationContetxtListener======OtherEvent");
System.out.println(event.toString());
}

}

}

<bean id="applicationContetxtListener" class="com.xxx.listener.ApplicationContetxtListener">
</bean>

看下输出

ApplicationContetxtListener===class org.springframework.web.context.support.ServletRequestHandledEvent
===ApplicationContetxtListener======ServletRequestHandledEvent
ServletRequestHandledEvent: url=[/productType/list.html]; client=[127.0.0.1]; method=[GET]; servlet=[mvc]; session=[null]; user=[null]; time=[6ms]; status=[OK]

如果需要统计用户请求接口信息，可以在这个地方做点文章。