Spring中的@PropertySource注解源码详细解析

/**
	 * Apply processing and build a complete {@link ConfigurationClass} by reading the
	 * annotations, members and methods from the source class. This method can be called
	 * multiple times as relevant sources are discovered.
	 * @param configClass the configuration class being build
	 * @param sourceClass a source class
	 * @return the superclass, or {@code null} if none found or previously processed
	 */
	protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
			throws IOException {
		// Recursively process any member (nested) classes first
		processMemberClasses(configClass, sourceClass);
		// Process any @PropertySource annotations
		for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable(
				sourceClass.getMetadata(), PropertySources.class,
				org.springframework.context.annotation.PropertySource.class)) {
			if (this.environment instanceof ConfigurableEnvironment) {
				processPropertySource(propertySource);
			}
			else {
				logger.warn("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
						"]. Reason: Environment must implement ConfigurableEnvironment");
			}
		}
    //......其余部分省略
}

static Set<AnnotationAttributes> attributesForRepeatable(
			AnnotationMetadata metadata, String containerClassName, String annotationClassName) {
		Set<AnnotationAttributes> result = new LinkedHashSet<AnnotationAttributes>();
		// Direct annotation present?
		addAttributesIfNotNull(result, metadata.getAnnotationAttributes(annotationClassName, false));
		// Container annotation present?
		Map<String, Object> container = metadata.getAnnotationAttributes(containerClassName, false);
		if (container != null && container.containsKey("value")) {
			for (Map<String, Object> containedAttributes : (Map<String, Object>[]) container.get("value")) {
				addAttributesIfNotNull(result, containedAttributes);
			}
		}
		// Return merged result
		return Collections.unmodifiableSet(result);
	}
private static void addAttributesIfNotNull(Set<AnnotationAttributes> result, Map<String, Object> attributes) {
		if (attributes != null) {
			result.add(AnnotationAttributes.fromMap(attributes));
		}
	}

/**
	 * Process the given <code>@PropertySource</code> annotation metadata.
	 * @param propertySource metadata for the <code>@PropertySource</code> annotation found
	 * @throws IOException if loading a property source failed
	 */
	private void processPropertySource(AnnotationAttributes propertySource) throws IOException {
		String name = propertySource.getString("name");
		if (!StringUtils.hasLength(name)) {
			name = null;
		}
		String encoding = propertySource.getString("encoding");
		if (!StringUtils.hasLength(encoding)) {
			encoding = null;
		}
		String[] locations = propertySource.getStringArray("value");
		Assert.isTrue(locations.length > 0, "At least one @PropertySource(value) location is required");
		boolean ignoreResourceNotFound = propertySource.getBoolean("ignoreResourceNotFound");
		Class<? extends PropertySourceFactory> factoryClass = propertySource.getClass("factory");
		PropertySourceFactory factory = (factoryClass == PropertySourceFactory.class ?
				DEFAULT_PROPERTY_SOURCE_FACTORY : BeanUtils.instantiateClass(factoryClass));
		for (String location : locations) {
			try {
				String resolvedLocation = this.environment.resolveRequiredPlaceholders(location);
				Resource resource = this.resourceLoader.getResource(resolvedLocation);
				addPropertySource(factory.createPropertySource(name, new EncodedResource(resource, encoding)));
			}
			catch (IllegalArgumentException ex) {
				// Placeholders not resolvable
				if (ignoreResourceNotFound) {
					if (logger.isInfoEnabled()) {
						logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage());
					}
				}
				else {
					throw ex;
				}
			}
			catch (IOException ex) {
				// Resource not found when trying to open it
				if (ignoreResourceNotFound &&
						(ex instanceof FileNotFoundException || ex instanceof UnknownHostException)) {
					if (logger.isInfoEnabled()) {
						logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage());
					}
				}
				else {
					throw ex;
				}
			}
		}
	}

/**
 * The default implementation for {@link PropertySourceFactory},
 * wrapping every resource in a {@link ResourcePropertySource}.
 *
 * @author Juergen Hoeller
 * @since 4.3
 * @see PropertySourceFactory
 * @see ResourcePropertySource
 */
public class DefaultPropertySourceFactory implements PropertySourceFactory {
	@Override
	public PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
		return (name != null ? new ResourcePropertySource(name, resource) : new ResourcePropertySource(resource));
	}
}

/**
	 * Create a PropertySource based on Properties loaded from the given resource.
	 * The name of the PropertySource will be generated based on the
	 * {@link Resource#getDescription() description} of the given resource.
	 */
	public ResourcePropertySource(EncodedResource resource) throws IOException {
		super(getNameForResource(resource.getResource()), PropertiesLoaderUtils.loadProperties(resource));
		this.resourceName = null;
	}

private void addPropertySource(PropertySource<?> propertySource) {
		String name = propertySource.getName();
		MutablePropertySources propertySources = ((ConfigurableEnvironment) this.environment).getPropertySources();
		if (propertySources.contains(name) && this.propertySourceNames.contains(name)) {
			// We've already added a version, we need to extend it
			PropertySource<?> existing = propertySources.get(name);
			PropertySource<?> newSource = (propertySource instanceof ResourcePropertySource ?
					((ResourcePropertySource) propertySource).withResourceName() : propertySource);
			if (existing instanceof CompositePropertySource) {
				((CompositePropertySource) existing).addFirstPropertySource(newSource);
			}
			else {
				if (existing instanceof ResourcePropertySource) {
					existing = ((ResourcePropertySource) existing).withResourceName();
				}
				CompositePropertySource composite = new CompositePropertySource(name);
				composite.addPropertySource(newSource);
				composite.addPropertySource(existing);
				propertySources.replace(name, composite);
			}
		}
		else {
			if (this.propertySourceNames.isEmpty()) {
				propertySources.addLast(propertySource);
			}
			else {
				String firstProcessed = this.propertySourceNames.get(this.propertySourceNames.size() - 1);
				propertySources.addBefore(firstProcessed, propertySource);
			}
		}
		this.propertySourceNames.add(name);
	}