6-spring boot -监听器

需要的jar

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

实例代码

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class StudyListener implements ServletContextListener {
	public void contextInitialized(ServletContextEvent sce) {
		System.out.println("StudyListener init...");

	}

	public void contextDestroyed(ServletContextEvent sce) {
		System.out.println("StudyListener destory...");

	}
}

实例化

方式一:

com.study.cxk.listener对应StudyListener所在的包
@ServletComponentScan(basePackages  = {"com.study.cxk.filter","com.study.cxk.listener"})

方式二：

@SpringBootApplication
public class StudySpringBootApplication {

	public static void main(String[] args) {
		SpringApplication.run(StudySpringBootApplication.class, args);
	}
	
	@Bean
	public ServletListenerRegistrationBean<StudyListener> servletRegisterBean(){
		return new ServletListenerRegistrationBean<StudyListener>(new StudyListener());
	} 
}

启动

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.1.RELEASE)

2020-07-18 12:51:56.154  INFO 7472 --- [           main] c.study.cxk.StudySpringBootApplication   : Starting StudySpringBootApplication on DESKTOP-VSPGF1T with PID 7472 (D:\code\studySpringBoot\target\classes started by Administrator in D:\code\studySpringBoot)
2020-07-18 12:51:56.155  INFO 7472 --- [           main] c.study.cxk.StudySpringBootApplication   : The following profiles are active: shanghai
2020-07-18 12:51:56.631  INFO 7472 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 9789 (http)
2020-07-18 12:51:56.635  INFO 7472 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-07-18 12:51:56.636  INFO 7472 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.36]
2020-07-18 12:51:56.675  INFO 7472 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-07-18 12:51:56.675  INFO 7472 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 496 ms
StudyListener init...
2020-07-18 12:51:56.770  INFO 7472 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-07-18 12:51:56.800  INFO 7472 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2020-07-18 12:51:56.854  INFO 7472 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 9789 (http) with context path ''
2020-07-18 12:51:56.859  INFO 7472 --- [           main] c.study.cxk.StudySpringBootApplication   : Started StudySpringBootApplication in 0.908 seconds (JVM running for 1.281)
2020-07-18 12:51:59.036  INFO 7472 --- [on(2)-127.0.0.1] inMXBeanRegistrar$SpringApplicationAdmin : Application shutdown requested.
StudyListener destory...
2020-07-18 12:51:59.148  INFO 7472 --- [on(2)-127.0.0.1] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

监听器的作用

主要作用是：做一些初始化的内容添加工作、设置一些基本的内容、比如一些参数或者是一些固定的对象等等