玩转 SpringBoot 2 快速整合 Listener

快速演示操作

第一步： 编写 Listener 并且在 Listener 类上声明 @WebListener 注解。具体代码如下：

@WebListener public class ApplicationListener implements ServletContextListener{ 	private Logger log = LoggerFactory.getLogger(ApplicationListener.class); 	 	@Override 	public void contextInitialized(ServletContextEvent sce) { 		log.info("ApplicationListener 监听器启动..."); 	} 	@Override 	public void contextDestroyed(ServletContextEvent sce) { 		log.info("ApplicationListener 监听器销毁..."); 	} }

第二步：通过 JavaConfig 方式将编写的 ApplicationListener 类注入到 Spring 的上下文中。

将自定义 ApplicationListener 传入到 ServletListenerRegistrationBean的构造中，然后创建 ServletListenerRegistrationBean Bean实例，具体代码如下：

@Configuration public class WebApplicationConfig { 	@Bean 	public ServletListenerRegistrationBean<ApplicationListener>  userServlet(){ 		return new ServletListenerRegistrationBean<ApplicationListener> (new ApplicationListener()); 	} }

或者在启动类上声明 @ServletComponentScan 注解，具体代码如下：

@SpringBootApplication @ServletComponentScan public class SpringbootExamplesApplication {  	public static void main(String[] args) { 		SpringApplication.run(SpringbootExamplesApplication.class, args); 	} }

测试

启动 SpirngBoot 项目会看到在 ApplicationListener 中定义 ApplicationListener 监听器销毁… 日志信息。

2019-10-04 00:58:39.361  INFO 5184 --- [  restartedMain] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/] 2019-10-04 00:58:39.375  INFO 5184 --- [  restartedMain] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*] 2019-10-04 00:58:39.376  INFO 5184 --- [  restartedMain] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2019-10-04 00:58:39.376  INFO 5184 --- [  restartedMain] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'formContentFilter' to: [/*] 2019-10-04 00:58:39.377  INFO 5184 --- [  restartedMain] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*] 2019-10-04 00:58:39.420  INFO 5184 --- [  restartedMain] c.lijunkui.listener.ApplicationListener  : ApplicationListener 监听器启动...

在启动状态下在此启动该项目，虽然会报错但是可以看到在ApplicationListener 中定义销毁的日志信息输出。

Caused by: java.net.BindException: Address already in use: bind 	at sun.nio.ch.Net.bind0(Native Method) ~[na:1.8.0_144] 	at sun.nio.ch.Net.bind(Net.java:433) ~[na:1.8.0_144] 	at sun.nio.ch.Net.bind(Net.java:425) ~[na:1.8.0_144] 	at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223) ~[na:1.8.0_144] 	at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74) ~[na:1.8.0_144] 	at org.apache.tomcat.util.net.NioEndpoint.initServerSocket(NioEndpoint.java:236) ~[tomcat-embed-core-9.0.12.jar:9.0.12] 	at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:210) ~[tomcat-embed-core-9.0.12.jar:9.0.12] 	at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:1108) ~[tomcat-embed-core-9.0.12.jar:9.0.12] 	at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:550) ~[tomcat-embed-core-9.0.12.jar:9.0.12] 	at org.apache.catalina.connector.Connector.startInternal(Connector.java:957) ~[tomcat-embed-core-9.0.12.jar:9.0.12] 	... 19 common frames omitted  2019-10-04 01:01:07.860  INFO 7864 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat] 2019-10-04 01:01:07.863  INFO 7864 --- [  restartedMain] c.lijunkui.listener.ApplicationListener  : ApplicationListener 监听器销毁... 2019-10-04 01:01:07.876  INFO 7864 --- [  restartedMain] ConditionEvaluationReportLoggingListener :

小结

SpringBoot 中整合 Listener步骤如下：

需要在Listener上声明 @WebListener

在启动类上声明@ServletComponentScan注解或者将

Listener通过ServletListenerRegistrationBean 进行包装然后通过 JavaConfig

方式将其注入到Spring上下文中。

代码示例

我本地环境如下：

SpringBoot Version: 2.1.0.RELEASE

Apache Maven Version： 3.6.0

Java Version： 1.8.0_144

IDEA：Spring Tools Suite (STS)

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