ParentContextApplicationContextInitializer Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/builder/ParentContextApplicationContextInitializer.java lines 35–98

public class ParentContextApplicationContextInitializer
		implements ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered {

	private int order = Ordered.HIGHEST_PRECEDENCE;

	private final ApplicationContext parent;

	public ParentContextApplicationContextInitializer(ApplicationContext parent) {
		this.parent = parent;
	}

	public void setOrder(int order) {
		this.order = order;
	}

	@Override
	public int getOrder() {
		return this.order;
	}

	@Override
	public void initialize(ConfigurableApplicationContext applicationContext) {
		if (applicationContext != this.parent) {
			applicationContext.setParent(this.parent);
			applicationContext.addApplicationListener(EventPublisher.INSTANCE);
		}
	}

	private static final class EventPublisher implements ApplicationListener<ContextRefreshedEvent>, Ordered {

		private static final EventPublisher INSTANCE = new EventPublisher();

		@Override
		public int getOrder() {
			return Ordered.HIGHEST_PRECEDENCE;
		}

		@Override
		public void onApplicationEvent(ContextRefreshedEvent event) {
			ApplicationContext context = event.getApplicationContext();
			if (context instanceof ConfigurableApplicationContext configurableApplicationContext
					&& context == event.getSource()) {
				context.publishEvent(new ParentContextAvailableEvent(configurableApplicationContext));
			}
		}

	}

	/**
	 * {@link ApplicationEvent} fired when a parent context is available.
	 */
	public static class ParentContextAvailableEvent extends ApplicationEvent {

		public ParentContextAvailableEvent(ConfigurableApplicationContext applicationContext) {
			super(applicationContext);
		}

		public ConfigurableApplicationContext getApplicationContext() {
			return (ConfigurableApplicationContext) getSource();
		}

	}

}