1.<context:annotation-config/>

xsd中說明：

<xsd:element name="annotation-config"> <xsd:annotation> <xsd:documentation> <![CDATA[ Activates various annotations to be detected in bean classes: Spring's @Required and @Autowired, as well as JSR 250's @PostConstruct, @PreDestroy and @Resource (if available), JAX-WS's @WebServiceRef (if available), EJB3's @EJB (if available), and JPA's @PersistenceContext and @PersistenceUnit (if available). Alternatively, you may choose to activate the individual BeanPostProcessors for those annotations. Note: This tag does not activate processing of Spring's @Transactional or EJB3's @TransactionAttribute annotation. Consider the use of the <tx:annotation-driven> tag for that purpose. ]]> </xsd:documentation> </xsd:annotation> </xsd:element>

解析發(fā)生在在解析xml文件中，解析類為：AnnotationConfigBeanDefinitionParser.java

public BeanDefinition parse(Element element, ParserContext parserContext) {Object source = parserContext.extractSource(element);// Obtain bean definitions for all relevant BeanPostProcessors. Set<BeanDefinitionHolder> processorDefinitions =AnnotationConfigUtils.registerAnnotationConfigProcessors(parserContext.getRegistry(), source);// Register component for the surrounding <context:annotation-config> element.CompositeComponentDefinition compDefinition = new CompositeComponentDefinition(element.getTagName(), source);parserContext.pushContainingComponent(compDefinition);// Nest the concrete beans in the surrounding component.for (BeanDefinitionHolder processorDefinition : processorDefinitions) {parserContext.registerComponent(new BeanComponentDefinition(processorDefinition));}// Finally register the composite component. parserContext.popAndRegisterContainingComponent();return null;}

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2.<context:component-scan/>

<xsd:element name="component-scan"> <xsd:annotation> <xsd:documentation> <![CDATA[ Scans the classpath for annotated components that will be auto-registered as Spring beans. By default, the Spring-provided @Component, @Repository, @Service, and @Controller stereotypes will be detected. Note: This tag implies the effects of the 'annotation-config' tag, activating @Required, @Autowired, @PostConstruct, @PreDestroy, @Resource, @PersistenceContext and @PersistenceUnit annotations in the component classes, which is usually desired for autodetected components (without external configuration). Turn off the 'annotation-config' attribute to deactivate this default behavior, for example in order to use custom BeanPostProcessor definitions for handling those annotations. Note: You may use placeholders in package paths, but only resolved against system properties (analogous to resource paths). A component scan results in new bean definition being registered; Spring's PropertyPlaceholderConfigurer will apply to those bean definitions just like to regular bean definitions, but it won't apply to the component scan settings themselves. ]]> </xsd:documentation> </xsd:annotation> <xsd:complexType> <xsd:sequence> <xsd:element name="include-filter" type="filterType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation> <![CDATA[ Controls which eligible types to include for component scanning. ]]> </xsd:documentation> </xsd:annotation> </xsd:element> <xsd:element name="exclude-filter" type="filterType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation> <![CDATA[ Controls which eligible types to exclude for component scanning. ]]> </xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="base-package" type="xsd:string" use="required"> <xsd:annotation> <xsd:documentation> <![CDATA[ The comma-separated list of packages to scan for annotated components. ]]> </xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="resource-pattern" type="xsd:string"> <xsd:annotation> <xsd:documentation> <![CDATA[ Controls the class files eligible for component detection. Defaults to "**/*.class", the recommended value. ]]> </xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="use-default-filters" type="xsd:boolean" default="true"> <xsd:annotation> <xsd:documentation> <![CDATA[ Indicates whether automatic detection of classes annotated with @Component, @Repository, @Service, or @Controller should be enabled. Default is "true". ]]> </xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="annotation-config" type="xsd:boolean" default="true"> <xsd:annotation> <xsd:documentation> <![CDATA[ Indicates whether the implicit annotation post-processors should be enabled. Default is "true". ]]> </xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="name-generator" type="xsd:string"> <xsd:annotation> <xsd:documentation> <![CDATA[ The fully-qualified class name of the BeanNameGenerator to be used for naming detected components. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="java.lang.Class"/> <tool:assignable-to type="org.springframework.beans.factory.support.BeanNameGenerator"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope-resolver" type="xsd:string"> <xsd:annotation> <xsd:documentation> <![CDATA[ The fully-qualified class name of the ScopeMetadataResolver to be used for resolving the scope of detected components. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="java.lang.Class"/> <tool:assignable-to type="org.springframework.context.annotation.ScopeMetadataResolver"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scoped-proxy"> <xsd:annotation> <xsd:documentation> <![CDATA[ Indicates whether proxies should be generated for detected components, which may be necessary when using scopes in a proxy-style fashion. Default is to generate no such proxies. ]]> </xsd:documentation> </xsd:annotation> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:enumeration value="no"/> <xsd:enumeration value="interfaces"/> <xsd:enumeration value="targetClass"/> </xsd:restriction> </xsd:simpleType> </xsd:attribute> </xsd:complexType> </xsd:element>

注意：紅色的一行中，說明<context:component-scan>包含<context:annotation-config>，且<context:annotation-config>的作用是：

Indicates whether automatic detection of classes annotated with @Component, @Repository, @Service, or @Controller should be enabled.

而<context:component-scan>解析發(fā)生在在解析xml文件中，解析類為：ComponentScanBeanDefinitionParser.java

public BeanDefinition parse(Element element, ParserContext parserContext) {String[] basePackages = StringUtils.tokenizeToStringArray(element.getAttribute(BASE_PACKAGE_ATTRIBUTE),ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);// Actually scan for bean definitions and register them.ClassPathBeanDefinitionScanner scanner = configureScanner(parserContext, element);Set<BeanDefinitionHolder> beanDefinitions = scanner.doScan(basePackages);registerComponents(parserContext.getReaderContext(), beanDefinitions, element);return null;}

注冊過程如下：

protected void registerComponents(XmlReaderContext readerContext, Set<BeanDefinitionHolder> beanDefinitions, Element element) {Object source = readerContext.extractSource(element);CompositeComponentDefinition compositeDef = new CompositeComponentDefinition(element.getTagName(), source);for (BeanDefinitionHolder beanDefHolder : beanDefinitions) {compositeDef.addNestedComponent(new BeanComponentDefinition(beanDefHolder));}// Register annotation config processors, if necessary.boolean annotationConfig = true;if (element.hasAttribute(ANNOTATION_CONFIG_ATTRIBUTE)) {annotationConfig = Boolean.valueOf(element.getAttribute(ANNOTATION_CONFIG_ATTRIBUTE));}if (annotationConfig) {Set<BeanDefinitionHolder> processorDefinitions =AnnotationConfigUtils.registerAnnotationConfigProcessors(readerContext.getRegistry(), source);for (BeanDefinitionHolder processorDefinition : processorDefinitions) {compositeDef.addNestedComponent(new BeanComponentDefinition(processorDefinition));}}readerContext.fireComponentRegistered(compositeDef);}

其中，紅色部分是關(guān)于<annotation-config>部分的。

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轉(zhuǎn)載于:https://www.cnblogs.com/davidwang456/p/5646093.html

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