BeanAdapter Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/convert/ApplicationConversionService.java lines 404–464

	abstract static class BeanAdapter<B> implements ConditionalGenericConverter {

		private final B bean;

		private final ResolvableTypePair types;

		BeanAdapter(B bean, ResolvableType beanType) {
			Assert.isInstanceOf(beanType.toClass(), bean);
			ResolvableType type = ResolvableType.forClass(getClass()).as(BeanAdapter.class).getGeneric();
			ResolvableType[] generics = beanType.as(type.toClass()).getGenerics();
			this.bean = bean;
			this.types = getResolvableTypePair(generics);
		}

		protected ResolvableTypePair getResolvableTypePair(ResolvableType[] generics) {
			return new ResolvableTypePair(generics[0], generics[1]);
		}

		protected B bean() {
			return this.bean;
		}

		@Override
		public Set<ConvertiblePair> getConvertibleTypes() {
			return Set.of(new ConvertiblePair(this.types.source().toClass(), this.types.target().toClass()));
		}

		@Override
		public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
			return (this.types.target().toClass() == targetType.getObjectType()
					&& matchesTargetType(targetType.getResolvableType()));
		}

		private boolean matchesTargetType(ResolvableType targetType) {
			ResolvableType ours = this.types.target();
			return targetType.getType() instanceof Class || targetType.isAssignableFrom(ours)
					|| this.types.target().hasUnresolvableGenerics();
		}

		protected final boolean conditionalConverterCandidateMatches(Object conditionalConverterCandidate,
				TypeDescriptor sourceType, TypeDescriptor targetType) {
			return (conditionalConverterCandidate instanceof ConditionalConverter conditionalConverter)
					? conditionalConverter.matches(sourceType, targetType) : true;
		}

		@SuppressWarnings({ "unchecked", "rawtypes" })
		protected final @Nullable Object convert(@Nullable Object source, TypeDescriptor targetType,
				Converter<?, ?> converter) {
			return (source != null) ? ((Converter) converter).convert(source) : convertNull(targetType);
		}

		private @Nullable Object convertNull(TypeDescriptor targetType) {
			return (targetType.getObjectType() != Optional.class) ? null : Optional.empty();
		}

		@Override
		public String toString() {
			return this.types + " : " + this.bean;
		}

	}