SharedMetadataReaderFactoryContextInitializer Class — spring-boot Architecture

Source Code

core/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/SharedMetadataReaderFactoryContextInitializer.java lines 57–222

class SharedMetadataReaderFactoryContextInitializer implements
		ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered, BeanRegistrationExcludeFilter {

	public static final String BEAN_NAME = "org.springframework.boot.autoconfigure."
			+ "internalCachingMetadataReaderFactory";

	@Override
	public void initialize(ConfigurableApplicationContext applicationContext) {
		if (AotDetector.useGeneratedArtifacts()) {
			return;
		}
		BeanFactoryPostProcessor postProcessor = new CachingMetadataReaderFactoryPostProcessor(applicationContext);
		applicationContext.addBeanFactoryPostProcessor(postProcessor);
	}

	@Override
	public int getOrder() {
		return 0;
	}

	@Override
	public boolean isExcludedFromAotProcessing(RegisteredBean registeredBean) {
		return BEAN_NAME.equals(registeredBean.getBeanName());
	}

	/**
	 * {@link BeanDefinitionRegistryPostProcessor} to register the
	 * {@link CachingMetadataReaderFactory} and configure the
	 * {@link ConfigurationClassPostProcessor}.
	 */
	static class CachingMetadataReaderFactoryPostProcessor
			implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {

		private final ConfigurableApplicationContext context;

		CachingMetadataReaderFactoryPostProcessor(ConfigurableApplicationContext context) {
			this.context = context;
		}

		@Override
		public int getOrder() {
			// Must happen before the ConfigurationClassPostProcessor is created
			return Ordered.HIGHEST_PRECEDENCE;
		}

		@Override
		public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		}

		@Override
		public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
			register(registry);
			configureConfigurationClassPostProcessor(registry);
		}

		private void register(BeanDefinitionRegistry registry) {
			if (!registry.containsBeanDefinition(BEAN_NAME)) {
				BeanDefinition definition = BeanDefinitionBuilder
					.rootBeanDefinition(SharedMetadataReaderFactoryBean.class, SharedMetadataReaderFactoryBean::new)
					.getBeanDefinition();
				registry.registerBeanDefinition(BEAN_NAME, definition);
			}
		}

		private void configureConfigurationClassPostProcessor(BeanDefinitionRegistry registry) {
			try {
				configureConfigurationClassPostProcessor(
						registry.getBeanDefinition(AnnotationConfigUtils.CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
			}
			catch (NoSuchBeanDefinitionException ex) {
				// Ignore
			}
		}

		private void configureConfigurationClassPostProcessor(BeanDefinition definition) {
			if (definition instanceof AbstractBeanDefinition abstractBeanDefinition) {
				configureConfigurationClassPostProcessor(abstractBeanDefinition);
				return;
			}
			configureConfigurationClassPostProcessor(definition.getPropertyValues());
		}

		private void configureConfigurationClassPostProcessor(AbstractBeanDefinition definition) {
			Supplier<?> instanceSupplier = definition.getInstanceSupplier();
			if (instanceSupplier != null) {
				definition.setInstanceSupplier(
						new ConfigurationClassPostProcessorCustomizingSupplier(this.context, instanceSupplier));
				return;
			}
			configureConfigurationClassPostProcessor(definition.getPropertyValues());
		}

		private void configureConfigurationClassPostProcessor(MutablePropertyValues propertyValues) {
			propertyValues.add("metadataReaderFactory", new RuntimeBeanReference(BEAN_NAME));
		}

	}

	/**
	 * {@link Supplier} used to customize the {@link ConfigurationClassPostProcessor} when
	 * it's first created.
	 */
	static class ConfigurationClassPostProcessorCustomizingSupplier implements Supplier<Object> {

		private final ConfigurableApplicationContext context;

		private final Supplier<?> instanceSupplier;

		ConfigurationClassPostProcessorCustomizingSupplier(ConfigurableApplicationContext context,
				Supplier<?> instanceSupplier) {
			this.context = context;
			this.instanceSupplier = instanceSupplier;
		}

		@Override
		public Object get() {
			Object instance = this.instanceSupplier.get();
			if (instance instanceof ConfigurationClassPostProcessor postProcessor) {
				configureConfigurationClassPostProcessor(postProcessor);
			}
			return instance;
		}

		private void configureConfigurationClassPostProcessor(ConfigurationClassPostProcessor instance) {
			instance.setMetadataReaderFactory(this.context.getBean(BEAN_NAME, MetadataReaderFactory.class));
		}

	}

	/**
	 * {@link FactoryBean} to create the shared {@link MetadataReaderFactory}.
	 */
	static class SharedMetadataReaderFactoryBean implements FactoryBean<CachingMetadataReaderFactory>,
			ResourceLoaderAware, ApplicationListener<ContextRefreshedEvent> {

		@SuppressWarnings("NullAway.Init")
		private CachingMetadataReaderFactory metadataReaderFactory;

		@Override
		public void setResourceLoader(ResourceLoader resourceLoader) {
			this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
		}

		@Override
		public CachingMetadataReaderFactory getObject() throws Exception {
			return this.metadataReaderFactory;
		}

		@Override
		public Class<?> getObjectType() {
			return CachingMetadataReaderFactory.class;
		}

		@Override
		public boolean isSingleton() {
			return true;
		}

		@Override
		public void onApplicationEvent(ContextRefreshedEvent event) {
			this.metadataReaderFactory.clearCache();
		}

	}

}