Add Grails like BootStrap functionality [SPR-9889]

[spring-projects-issues]

Marcel Overdijk opened SPR-9889 and commented

It would be very nice to have simple BootStrap functionality like Grails available:

class BootStrap {

	def init = { servletContext ->
	}

	def destroy = {
	}
}

It would be nice to configure such classes in AppConfig or maybe just an annotation would be enough?

---

Issue Links:

• Improved support for 'containerless' web application architectures [SPR-9888] #14521 Improved support for 'containerless' web application architectures

[spring-projects-issues]

Chris Beams commented

Hi Marcel,

Could you provide a bit more context here? i.e. what would you like to configure in these classes? How would you see them working with regard to typical Spring (web) application needs? Feel free to brainstorm, and see #14521 in the meantime.

[spring-projects-issues]

Marcin Kuthan commented

Hi Chris, Marcel

Some sort of support for application bootstrap would be really useful. I implemented bootstrap feature with Spring application listener and events:

@Component
public class ApplicationBootstrap implements ApplicationListener<ContextRefreshedEvent> {

	@Override
	public void onApplicationEvent(ContextRefreshedEvent event) {
		ApplicationContext applicationContext = event.getApplicationContext();

		if (isRootApplicationContext(applicationContext)) {
			event.getApplicationContext().publishEvent(new BootstrapEvent(applicationContext));
		}

	}

	private boolean isRootApplicationContext(ApplicationContext applicationContext) {
		return applicationContext.getParent() == null;
	}

}

Listeners are ordered so there is built-in feature to decouple listeners if there are bootstrap process dependencies.

@Component
@Profile("local")
public class ExampleBootstrapListener implements ApplicationListener<BootstrapEvent>, Ordered {

	@Autowired
	private ExampleRepository exampleRepository;

	@Override
	@Transactional
	public void onApplicationEvent(BootstrapEvent event) {
		if (!examplesExist()) {
                    ...
		}
	}

	@Override
	public int getOrder() {
		return BootstrapOrder.EXAMPLE;
	}

	private boolean examplesExist() {
		return exampleRepository.count() > 0;
	}
}

You can find example project at: https://github.com/mkuthan/example-spring/. Do we need abstraction layer on top spring events/listeners for application bootstrap? I'm not sure.

[spring-projects-issues]

Sébastien Deleuze commented

I guess Spring Boot is a better answer for this issue.