SpringBoot Application共支持6种事件监听，按顺序分别是：
- ApplicationStartingEvent：在Spring最开始启动的时候触发
- ApplicationEnvironmentPreparedEvent：在Spring已经准备好上下文但是上下文尚未创建的时候触发
- ApplicationPreparedEvent：在Bean定义加载之后、刷新上下文之前触发
- ApplicationStartedEvent：在刷新上下文之后、调用application命令之前触发
- ApplicationReadyEvent：在调用applicaiton命令之后触发
- ApplicationFailedEvent：在启动Spring发生异常时触发
另外：
- ApplicationRunner和CommandLineRunner的执行在第五步和第六步之间
- Bean的创建在第三步和第四步之间
- 在启动类中，执行SpringApplication.run()方法后的代码，会在第六步后执行
多说无益，直接上代码：
public class ApplicationStartingEventListener implements ApplicationListener<ApplicationStartingEvent> { @Override public void onApplicationEvent(ApplicationStartingEvent applicationStartingEvent) { System.out.println("============>>>>> applicationStartingEvent is trigged"); System.out.println(applicationStartingEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
public class ApplicationEnvironmentPreparedEventListener implements ApplicationListener<ApplicationEnvironmentPreparedEvent> { @Override public void onApplicationEvent(ApplicationEnvironmentPreparedEvent applicationEnvironmentPreparedEvent) { System.out.println("============>>>>> ApplicationEnvironmentPreparedEvent is trigged"); System.out.println(applicationEnvironmentPreparedEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
public class ApplicationPreparedEventListener implements ApplicationListener<ApplicationPreparedEvent> { @Override public void onApplicationEvent(ApplicationPreparedEvent applicationPreparedEvent) { System.out.println("============>>>>> applicationPreparedEvent is trigged"); System.out.println(applicationPreparedEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
public class ApplicationStartedEventListener implements ApplicationListener<ApplicationStartedEvent> { @Override public void onApplicationEvent(ApplicationStartedEvent applicationStartedEvent) { System.out.println("============>>>>> applicationStartedEvent is trigged"); System.out.println(applicationStartedEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
public class ApplicationReadyEventListener implements ApplicationListener<ApplicationReadyEvent> { @Override public void onApplicationEvent(ApplicationReadyEvent applicationReadyEvent) { System.out.println("============>>>>> applicationReadyEvent is trigged"); System.out.println(applicationReadyEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
public class ApplicationFailedEventListener implements ApplicationListener<ApplicationFailedEvent> { @Override public void onApplicationEvent(ApplicationFailedEvent applicationFailedEvent) { System.out.println("============>>>>> ApplicationFailedEvent is trigged"); System.out.println(applicationFailedEvent.getTimestamp()); System.out.println("============>>>>> End"); } }
@SpringBootApplication public class SpringBootTestApplication { public static void main(String[] args) { SpringApplication springApplication = new SpringApplication(SpringBootTestApplication.class); springApplication.addListeners(new ApplicationEnvironmentPreparedEventListener()); springApplication.addListeners(new ApplicationFailedEventListener()); springApplication.addListeners(new ApplicationPreparedEventListener()); springApplication.addListeners(new ApplicationReadyEventListener()); springApplication.addListeners(new ApplicationStartedEventListener()); springApplication.addListeners(new ApplicationStartingEventListener()); springApplication.run(args); } }
运行结果：
Connected to the target VM, address: '127.0.0.1:62927', transport: 'socket' ============>>>>> applicationStartingEvent is trigged 1541055154248 ============>>>>> End ============>>>>> ApplicationEnvironmentPreparedEvent is trigged 1541055154320 ============>>>>> End . ____ _ __ _ _ /\ / ___'_ __ _ _(_)_ __ __ _ ( ( )\___ | '_ | '_| | '_ / _` | \/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.0.3.RELEASE) 2018-11-01 14:52:35.117 INFO 2044 --- [ main] c.l.s.b.test.SpringBootTestApplication : Starting SpringBootTestApplication on EDIANZU-ETGVGB5 with PID 2044 (D:CodeSelfCodeSpringCloudTestSpringBootTest argetclasses started by Administrator in D:CodeSelfCodeSpringCloud) 2018-11-01 14:52:35.122 INFO 2044 --- [ main] c.l.s.b.test.SpringBootTestApplication : No active profile set, falling back to default profiles: default ============>>>>> applicationPreparedEvent is trigged 1541055155205 ============>>>>> End 2018-11-01 14:52:35.212 INFO 2044 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3406472c: startup date [Thu Nov 01 14:52:35 CST 2018]; root of context hierarchy 2018-11-01 14:52:36.891 INFO 2044 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2018-11-01 14:52:36.920 INFO 2044 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2018-11-01 14:52:36.920 INFO 2044 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.31 2018-11-01 14:52:36.925 INFO 2044 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [D:Program FilesJavajdk1.8.0_191in;C:WindowsSunJavain;C:Windowssystem32;C:Windows;C:Program Files (x86)Common FilesOracleJavajavapath;C:Program Files (x86)InteliCLS Client;C:Program FilesInteliCLS Client;C:Windowssystem32;C:Windows;C:WindowsSystem32Wbem;C:WindowsSystem32WindowsPowerShellv1.0;C:Program Files (x86)IntelIntel(R) Management Engine ComponentsDAL;C:Program FilesIntelIntel(R) Management Engine ComponentsDAL;C:Program Files (x86)IntelIntel(R) Management Engine ComponentsIPT;C:Program FilesIntelIntel(R) Management Engine ComponentsIPT;C:Program FilesIntelWiFiin;C:Program FilesCommon FilesIntelWirelessCommon;C:Program FilesThinkPadBluetooth Software;C:Program FilesThinkPadBluetooth Softwaresyswow64;C:Program Files (x86)IntelOpenCL SDK2.0inx86;C:Program Files (x86)IntelOpenCL SDK2.0inx64;D:Program FilesJavajdk1.8.0_191in;D:Program FilesGitcmd;D:Program Filesapache-maven-3.5.4in;C:Program FilesIntelWiFiin;C:Program FilesCommon FilesIntelWirelessCommon;.] 2018-11-01 14:52:37.048 INFO 2044 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2018-11-01 14:52:37.048 INFO 2044 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1841 ms 2018-11-01 14:52:37.377 INFO 2044 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/] 2018-11-01 14:52:37.389 INFO 2044 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2018-11-01 14:52:37.390 INFO 2044 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2018-11-01 14:52:37.390 INFO 2044 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2018-11-01 14:52:37.390 INFO 2044 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2018-11-01 14:52:37.598 INFO 2044 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-11-01 14:52:37.857 INFO 2044 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3406472c: startup date [Thu Nov 01 14:52:35 CST 2018]; root of context hierarchy 2018-11-01 14:52:37.922 INFO 2044 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2018-11-01 14:52:37.923 INFO 2044 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) 2018-11-01 14:52:37.973 INFO 2044 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-11-01 14:52:37.973 INFO 2044 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-11-01 14:52:38.160 INFO 2044 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2018-11-01 14:52:38.206 INFO 2044 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path '' 2018-11-01 14:52:38.212 INFO 2044 --- [ main] c.l.s.b.test.SpringBootTestApplication : Started SpringBootTestApplication in 3.976 seconds (JVM running for 5.088) ============>>>>> applicationStartedEvent is trigged 1541055158213 ============>>>>> End ============>>>>> applicationReadyEvent is trigged 1541055158214 ============>>>>> End