Seen Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/web/servlet/ServletContextInitializerBeans.java lines 411–439

	private static final class Seen {

		private final Map<Class<?>, Set<Object>> seen = new HashMap<>();

		boolean add(Class<?> type, Object object) {
			if (contains(type, object)) {
				return false;
			}
			return this.seen.computeIfAbsent(type, (ignore) -> new HashSet<>()).add(object);
		}

		boolean contains(Class<?> type, Object object) {
			if (this.seen.isEmpty()) {
				return false;
			}
			// If it has been directly seen, or the implemented ServletContextInitializer
			// has been seen already
			if (type != ServletContextInitializer.class
					&& this.seen.getOrDefault(type, Collections.emptySet()).contains(object)) {
				return true;
			}
			return this.seen.getOrDefault(ServletContextInitializer.class, Collections.emptySet()).contains(object);
		}

		static Seen empty() {
			return new Seen();
		}

	}