Bean Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java lines 263–333

	static class Bean<T> extends BeanProperties {

		Bean(ResolvableType type, Class<?> resolvedType) {
			super(type, resolvedType);
		}

		@SuppressWarnings("unchecked")
		BeanSupplier<T> getSupplier(Bindable<T> target) {
			return new BeanSupplier<>(() -> {
				T instance = null;
				if (target.getValue() != null) {
					instance = target.getValue().get();
				}
				if (instance == null) {
					instance = (T) BeanUtils.instantiateClass(getResolvedType());
				}
				return instance;
			});
		}

		@SuppressWarnings("unchecked")
		static <T> @Nullable Bean<T> get(Bindable<T> bindable, Context context, boolean canCallGetValue) {
			ResolvableType type = bindable.getType();
			Class<?> resolvedType = type.resolve(Object.class);
			Supplier<T> value = bindable.getValue();
			T instance = null;
			if (canCallGetValue && value != null) {
				instance = value.get();
				resolvedType = (instance != null) ? instance.getClass() : resolvedType;
			}
			if (instance == null && !isInstantiable(resolvedType)) {
				return null;
			}
			Map<CacheKey, Bean<?>> cache = getCache(context);
			CacheKey cacheKey = new CacheKey(type, resolvedType);
			Bean<?> bean = cache.get(cacheKey);
			if (bean == null) {
				bean = new Bean<>(type, resolvedType);
				cache.put(cacheKey, bean);
			}
			return (Bean<T>) bean;
		}

		@SuppressWarnings("unchecked")
		private static Map<CacheKey, Bean<?>> getCache(Context context) {
			Map<CacheKey, Bean<?>> cache = (Map<CacheKey, Bean<?>>) context.getCache().get(Bean.class);
			if (cache == null) {
				cache = new ConcurrentHashMap<>();
				context.getCache().put(Bean.class, cache);
			}
			return cache;
		}

		private static boolean isInstantiable(Class<?> type) {
			if (type.isInterface()) {
				return false;
			}
			try {
				type.getDeclaredConstructor();
				return true;
			}
			catch (Exception ex) {
				return false;
			}
		}

		private record CacheKey(ResolvableType type, Class<?> resolvedType) {

		}

	}