Spring boot: Start an application automatically wh

Assume I have a SpringBoot Application deployed as a WAR to Websphere Application Server (WAS). This WAR contains a daemon, so it must start straight away when WAS starts (and only once).

However, I still need to activate the SpringBoot Servlet by doing a http request.

Now I understand that the concept of servlets is to act on http requests, I still want to get it auto started on appserver start. This makes my daemon portable from standalone jar/main to war/webapp.

I tried a ServletContextListener, but the contextInitalized also get only called at the first http request.

I do not have a web.xml (servlet 3).

Code:

@SpringBootApplication
@WebListener
public class DemoApplication extends SpringBootServletInitializer implements ServletContextListener {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        System.err.println("ONSTARTUP"); 
        super.onStartup(servletContext);
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    } 

   @Override
   protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
      return application.sources(DemoApplication.class);
   }


    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.err.println("contextInitialized"); 
    }

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        //
    }
}

and:

@Component
public class DemoRunner implements ApplicationRunner {

    @Override
    public void run(ApplicationArguments arg0) throws Exception {
        System.err.println("I AM RUNNING");
    }

}

When I start WAS I first get this:

Launching defaultServer (WebSphere Application Server
16.0.0.2/wlp-1.0.13.cl160220160526-2258) on Java HotSpot(TM) 64-Bit Server VM, version 1.7.0_79-b15 (en_US) 
[...]  
[AUDIT   ] CWWKT0016I: Web application available (default_host): http://localhost:9080/demo/ 
[AUDIT   ] CWWKZ0001I: Application test started in 17,282 seconds.

To get my Spring Boot application starting, I first need to visit this link (http:/localhost:9080/demo/). Then it starts rolling, starting with the startup method as you can see in the log. But how can I get this starting without doing a http request?

[err] ONSTARTUP
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.4.0.RELEASE)
2016-09-02 10:45:52.670  INFO 23716 --- [dPool-thread-48] com.example.DemoApplication              : Starting DemoApplication on [...]
2016-09-02 10:45:58.019  INFO 23716 --- [dPool-thread-48] o.s.c.support.DefaultLifecycleProcessor  : Starting beans in phase 0
[...]
[err] I AM RUNNING
[...]
2016-09-02 10:45:58.093  INFO 23716 --- [dPool-thread-48] com.example.DemoApplication              : Started DemoApplication in 6.372 seconds (JVM running for 31.549)
[...]
[err] contextInitialized
[err] contextInitialized

You can change the loadOnStartup by customize the spring dispatch servlet, here is the sample question and you can use the code

@Bean
public static BeanFactoryPostProcessor beanFactoryPostProcessor() {
    return new BeanFactoryPostProcessor() {

        @Override
        public void postProcessBeanFactory(
                ConfigurableListableBeanFactory beanFactory) throws BeansException {
            BeanDefinition bean = beanFactory.getBeanDefinition(
                    DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME);

            bean.getPropertyValues().add("loadOnStartup", 1);
        }
    };
}

Reference: how to configure 'dispatcherServlet' load on startup by spring boot?

Upate

Seems there is a more simple way, you can config it in application.properites

spring.mvc.servlet.load-on-startup=1