Adds an event listener to the namespace specified by the annotation

[588q9]

my application requirement need let namespace for more useful，so I add that code for title statement uitlity，if have any problem about destroy hook or more that,I will listen carefully to your advice.

[shutuper]

You can do it by yourself, in my projects I add:

/**
 * Types that carry this annotation are treated as namespace event listeners.
 * Class should contain methods annotated with:
 * {@link com.corundumstudio.socketio.annotation.OnConnect @OnConnect}
 * {@link com.corundumstudio.socketio.annotation.OnDisconnect @OnDisconnect}
 * {@link com.corundumstudio.socketio.annotation.OnEvent @OnEvent}
 * @see AppServerEventListener
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Namespace {

	/**
	 * The value decides to which namespace current listener should be attached,
	 * the same value can be reused to a few listeners
	 */
	String value() default DEFAULT_NAME; // ""

}

/**
 * A class that listens for application/context events.
 * Registers socket.io namespace listeners and shuts down the server
 * */
@Slf4j
@Component
@RequiredArgsConstructor
@FieldDefaults(makeFinal = true, level = PRIVATE)
public class AppServerEventListener {

	SocketIOServer socketIOServer;

	@EventListener(ApplicationReadyEvent.class)
	public void registerNamespacesEventListeners(ApplicationReadyEvent readyEvent) {
		ConfigurableApplicationContext applicationContext = readyEvent.getApplicationContext();
		Map<String, Object> beansWithNamespace = applicationContext.getBeansWithAnnotation(Namespace.class);

		if (beansWithNamespace.isEmpty()) {
			log.warn("No socket.io namespace listeners found");
		}

		beansWithNamespace.forEach((beanName, bean) -> Optional.ofNullable(
						applicationContext.findAnnotationOnBean(beanName, Namespace.class)
				).ifPresent(namespace -> {
					socketIOServer
							.addNamespace(namespace.value())
							.addListeners(bean, bean.getClass());

					log.info("{} listener added to {} socket.io namespace", beanName, namespace.value());
				})
		);
	}

	@EventListener(ContextClosedEvent.class)
	public void shutDownSocketIOServer() {
		socketIOServer.stop();
	}

}

Then you can create classes annotated with @Namespace & @Component and declare methods annotated with @OnConnect/@OnEvent/@OnDisconnect. With this approach you don't need to create SpringAnnotationScanner bean

[588q9]

You can do it by yourself, in my projects I add:

/**
 * Types that carry this annotation are treated as namespace event listeners.
 * Class should contain methods annotated with:
 * {@link com.corundumstudio.socketio.annotation.OnConnect @OnConnect}
 * {@link com.corundumstudio.socketio.annotation.OnDisconnect @OnDisconnect}
 * {@link com.corundumstudio.socketio.annotation.OnEvent @OnEvent}
 * @see AppServerEventListener
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Namespace {

	/**
	 * The value decides to which namespace current listener should be attached,
	 * the same value can be reused to a few listeners
	 */
	String value() default DEFAULT_NAME; // ""

}

/**
 * A class that listens for application/context events.
 * Registers socket.io namespace listeners and shuts down the server
 * */
@Slf4j
@Component
@RequiredArgsConstructor
@FieldDefaults(makeFinal = true, level = PRIVATE)
public class AppServerEventListener {

	SocketIOServer socketIOServer;

	@EventListener(ApplicationReadyEvent.class)
	public void registerNamespacesEventListeners(ApplicationReadyEvent readyEvent) {
		ConfigurableApplicationContext applicationContext = readyEvent.getApplicationContext();
		Map<String, Object> beansWithNamespace = applicationContext.getBeansWithAnnotation(Namespace.class);

		if (beansWithNamespace.isEmpty()) {
			log.warn("No socket.io namespace listeners found");
		}

		beansWithNamespace.forEach((beanName, bean) -> Optional.ofNullable(
						applicationContext.findAnnotationOnBean(beanName, Namespace.class)
				).ifPresent(namespace -> {
					socketIOServer
							.addNamespace(namespace.value())
							.addListeners(bean, bean.getClass());

					log.info("{} listener added to {} socket.io namespace", beanName, namespace.value());
				})
		);
	}

	@EventListener(ContextClosedEvent.class)
	public void shutDownSocketIOServer() {
		socketIOServer.stop();
	}

}

Then you can create classes annotated with @Namespace & @Component and declare methods annotated with @OnConnect/@OnEvent/@OnDisconnect. With this approach you don't need to create SpringAnnotationScanner bean

wow！this look like is a good combine with spring，but what is function of namespace ?I think that can use for distinctive function of socket

[shutuper]

Namespace just logically groups sockets(each of them can be connected to many namespaces, at least to the default ("/") one, which contains all sockets). In most cases you can just use the default one and group sockets by rooms (also you can add distinctive parametrs to socket)
(more info here: https://socket.io/docs/v4/namespaces/ )