DefaultValuesBindHandler Class — spring-boot Architecture

Source Code

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindHandlerAdvisorTests.java lines 120–155

	static class DefaultValuesBindHandler extends AbstractBindHandler {

		private final Map<ConfigurationPropertyName, ConfigurationPropertyName> mappings;

		DefaultValuesBindHandler(BindHandler bindHandler) {
			super(bindHandler);
			this.mappings = new LinkedHashMap<>();
			this.mappings.put(ConfigurationPropertyName.of("foo.bar.bindings"),
					ConfigurationPropertyName.of("foo.bar.default"));
		}

		@Override
		public <T> @Nullable Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target,
				BindContext context) {
			ConfigurationPropertyName defaultName = getDefaultName(name);
			if (defaultName != null) {
				BindResult<T> result = context.getBinder().bind(defaultName, target);
				if (result.isBound()) {
					return target.withExistingValue(result.get());
				}
			}
			return super.onStart(name, target, context);
		}

		private @Nullable ConfigurationPropertyName getDefaultName(ConfigurationPropertyName name) {
			for (Map.Entry<ConfigurationPropertyName, ConfigurationPropertyName> mapping : this.mappings.entrySet()) {
				ConfigurationPropertyName from = mapping.getKey();
				ConfigurationPropertyName to = mapping.getValue();
				if (name.getNumberOfElements() == from.getNumberOfElements() + 1 && from.isParentOf(name)) {
					return to;
				}
			}
			return null;
		}

	}