Callbacks Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/util/LambdaSafe.java lines 283–325

	public static final class Callbacks<C, A> extends LambdaSafeCallback<C, A, Callbacks<C, A>> {

		private final Collection<? extends C> callbackInstances;

		private Callbacks(Class<C> callbackType, Collection<? extends C> callbackInstances, A argument,
				Object[] additionalArguments) {
			super(callbackType, argument, additionalArguments);
			this.callbackInstances = callbackInstances;
		}

		/**
		 * Invoke the callback instances where the callback method returns void.
		 * @param invoker the invoker used to invoke the callback
		 */
		public void invoke(Consumer<C> invoker) {
			this.callbackInstances.forEach((callbackInstance) -> {
				Supplier<@Nullable Void> supplier = () -> {
					invoker.accept(callbackInstance);
					return null;
				};
				invoke(callbackInstance, supplier);
			});
		}

		/**
		 * Invoke the callback instances where the callback method returns a result.
		 * @param invoker the invoker used to invoke the callback
		 * @param <R> the result type
		 * @return the results of the invocation (may be an empty stream if no callbacks
		 * could be called)
		 */
		public <R> Stream<R> invokeAnd(Function<C, @Nullable R> invoker) {
			Function<C, InvocationResult<R>> mapper = (callbackInstance) -> {
				Supplier<@Nullable R> supplier = () -> invoker.apply(callbackInstance);
				return invoke(callbackInstance, supplier);
			};
			return this.callbackInstances.stream()
				.map(mapper)
				.filter(InvocationResult::hasResult)
				.map(InvocationResult::get);
		}

	}