AvailabilityChangeEvent Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/availability/AvailabilityChangeEvent.java lines 37–95

public class AvailabilityChangeEvent<S extends AvailabilityState> extends PayloadApplicationEvent<S> {

	/**
	 * Create a new {@link AvailabilityChangeEvent} instance.
	 * @param source the source of the event
	 * @param state the availability state (never {@code null})
	 */
	public AvailabilityChangeEvent(Object source, S state) {
		super(source, state);
	}

	/**
	 * Return the changed availability state.
	 * @return the availability state
	 */
	public S getState() {
		return getPayload();
	}

	@Override
	public ResolvableType getResolvableType() {
		return ResolvableType.forClassWithGenerics(getClass(), getStateType());
	}

	private Class<?> getStateType() {
		S state = getState();
		if (state instanceof Enum<?> enumState) {
			return enumState.getDeclaringClass();
		}
		return state.getClass();
	}

	/**
	 * Convenience method that can be used to publish an {@link AvailabilityChangeEvent}
	 * to the given application context.
	 * @param <S> the availability state type
	 * @param context the context used to publish the event
	 * @param state the changed availability state
	 */
	public static <S extends AvailabilityState> void publish(ApplicationContext context, S state) {
		Assert.notNull(context, "'context' must not be null");
		publish(context, context, state);
	}

	/**
	 * Convenience method that can be used to publish an {@link AvailabilityChangeEvent}
	 * to the given application context.
	 * @param <S> the availability state type
	 * @param publisher the publisher used to publish the event
	 * @param source the source of the event
	 * @param state the changed availability state
	 */
	public static <S extends AvailabilityState> void publish(ApplicationEventPublisher publisher, Object source,
			S state) {
		Assert.notNull(publisher, "'publisher' must not be null");
		publisher.publishEvent(new AvailabilityChangeEvent<>(source, state));
	}

}