springboot2.2.6.RELEASE chapter7

Application events are sent in the following order, as your application runs:

1. An ApplicationStartingEvent is sent at the start of a run but before any processing, except for
   the registration of listeners and initializers.
2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context is
   known but before the context is created.
3. An ApplicationContextInitializedEvent is sent when the ApplicationContext is prepared and
   ApplicationContextInitializers have been called but before any bean definitions are loaded.
4. An ApplicationPreparedEvent is sent just before the refresh is started but after bean definitions
   have been loaded.
5. An ApplicationStartedEvent is sent after the context has been refreshed but before any
   application and command-line runners have been called.
6. An ApplicationReadyEvent is sent after any application and command-line runners have been
   called. It indicates that the application is ready to service requests.
   50
7. An ApplicationFailedEvent is sent

example:
Listener

public class ApplicationPreparedEventListener implements ApplicationListener<ApplicationPreparedEvent> {
    public void onApplicationEvent(ApplicationPreparedEvent event) {
        System.out.println("......ApplicationPreparedEvent......");
    }
}

Main

    public static void main(String[] args) {
//        SpringApplication.run(DemoApplication.class, args);
        SpringApplication springApplication = new SpringApplication(DemoApplication.class);
        springApplication.addListeners(new ApplicationPreparedEventListener());
        springApplication.run(args);
    }

输出：

2020-04-04 00:07:15.888  INFO 9672 --- [           main] com.github.examples.DemoApplication      : Starting DemoApplication on DESKTOP-GLVVPCF with PID 9672 (D:\03github\springboot2-learning\chapter3\target\classes started by limiao in D:\03github\springboot2-learning)
2020-04-04 00:07:15.910  INFO 9672 --- [           main] com.github.examples.DemoApplication      : No active profile set, falling back to default profiles: default
......ApplicationPreparedEvent......
2020-04-04 00:07:18.364  INFO 9672 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-04-04 00:07:18.383  INFO 9672 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-04-04 00:07:18.384  INFO 9672 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.33]
2020-04-04 00:07:18.544  INFO 9672 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-04-04 00:07:18.544  INFO 9672 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2457 ms
2020-04-04 00:07:18.906  INFO 9672 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-04-04 00:07:19.011  INFO 9672 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [public/index.html]
2020-04-04 00:07:19.202  INFO 9672 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2020-04-04 00:07:19.207  INFO 9672 --- [           main] com.github.examples.DemoApplication      : Started DemoApplication in 4.214 seconds (JVM running for 6.12)