Spring源码情操陶冶-AnnotationConfigBeanDefinitionParser注解配置解析器

本文承接前文Spring源码情操陶冶-自定义节点的解析，分析spring中的context:annotation-config节点如何被解析

源码概览

对BeanDefinitionParser接口的实现方法parse代码如下

@Override
	public BeanDefinition parse(Element element, ParserContext parserContext) {
		Object source = parserContext.extractSource(element);

		// Obtain bean definitions for all relevant BeanPostProcessors.主要的作用就是配置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;
	}

由上可述，我们明白了为什么配置了context:component-scan节点等同于不需要配置context:annotation-config节点，此处的代码类同与ComponentScanBeanDefinitionParser#registerComponents方法，所以这里就不赘述了，可见>>>Spring源码情操陶冶-ComponentScanBeanDefinitionParser文件扫描解析器的ComponentScanBeanDefinitionParser#registerComponents版块

小结

注册多个BeanPostProcessor接口实现类【供后续spring调用统一接口进行解析，比如>>>Spring源码情操陶冶-AbstractApplicationContext#invokeBeanFactoryPostProcessors可会执行解析@Configuration】具体的有

• ConfigurationClassPostProcessor解析@Configuration注解类

• AutowiredAnnotationBeanPostProcessor解析@Autowired/@Value注解

• RequiredAnnotationBeanPostProcessor解析@Required注解

• CommonAnnotationBeanPostProcessor解析@Resource注解

• PersistenceAnnotationBeanPostProcessor解析JPA注解，持久层