ConfigurationPropertiesScanRegistrar Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesScanRegistrar.java lines 51–127

class ConfigurationPropertiesScanRegistrar implements ImportBeanDefinitionRegistrar {

	private final Environment environment;

	private final @Nullable ResourceLoader resourceLoader;

	ConfigurationPropertiesScanRegistrar(Environment environment, @Nullable ResourceLoader resourceLoader) {
		this.environment = environment;
		this.resourceLoader = resourceLoader;
	}

	@Override
	public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
		Set<String> packagesToScan = getPackagesToScan(importingClassMetadata);
		scan(registry, packagesToScan);
	}

	private Set<String> getPackagesToScan(AnnotationMetadata metadata) {
		AnnotationAttributes attributes = AnnotationAttributes
			.fromMap(metadata.getAnnotationAttributes(ConfigurationPropertiesScan.class.getName()));
		Assert.state(attributes != null, "'attributes' must not be null");
		String[] basePackages = attributes.getStringArray("basePackages");
		Class<?>[] basePackageClasses = attributes.getClassArray("basePackageClasses");
		Set<String> packagesToScan = new LinkedHashSet<>(Arrays.asList(basePackages));
		for (Class<?> basePackageClass : basePackageClasses) {
			packagesToScan.add(ClassUtils.getPackageName(basePackageClass));
		}
		if (packagesToScan.isEmpty()) {
			packagesToScan.add(ClassUtils.getPackageName(metadata.getClassName()));
		}
		packagesToScan.removeIf((candidate) -> !StringUtils.hasText(candidate));
		return packagesToScan;
	}

	private void scan(BeanDefinitionRegistry registry, Set<String> packages) {
		ConfigurationPropertiesBeanRegistrar registrar = new ConfigurationPropertiesBeanRegistrar(registry);
		ClassPathScanningCandidateComponentProvider scanner = getScanner(registry);
		for (String basePackage : packages) {
			for (BeanDefinition candidate : scanner.findCandidateComponents(basePackage)) {
				String beanClassName = candidate.getBeanClassName();
				Assert.state(beanClassName != null, "'beanClassName' must not be null");
				register(registrar, beanClassName);
			}
		}
	}

	private ClassPathScanningCandidateComponentProvider getScanner(BeanDefinitionRegistry registry) {
		ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
		scanner.setEnvironment(this.environment);
		scanner.setResourceLoader(this.resourceLoader);
		scanner.addIncludeFilter(new AnnotationTypeFilter(ConfigurationProperties.class));
		TypeExcludeFilter typeExcludeFilter = new TypeExcludeFilter();
		typeExcludeFilter.setBeanFactory((BeanFactory) registry);
		scanner.addExcludeFilter(typeExcludeFilter);
		return scanner;
	}

	private void register(ConfigurationPropertiesBeanRegistrar registrar, String className) throws LinkageError {
		try {
			register(registrar, ClassUtils.forName(className, null));
		}
		catch (ClassNotFoundException ex) {
			// Ignore
		}
	}

	private void register(ConfigurationPropertiesBeanRegistrar registrar, Class<?> type) {
		if (!isComponent(type)) {
			registrar.register(type);
		}
	}

	private boolean isComponent(Class<?> type) {
		return MergedAnnotations.from(type, SearchStrategy.TYPE_HIERARCHY).isPresent(Component.class);
	}

}