AbstractApplicationContext#refresh()
AbstractApplicationContext#obtainFreshBeanFactory()
AbstractApplicationContext#refreshBeanFactory()
AbstractBeanDefinitionReader#loadBeanDefinitions
AbstractBeanDefinitionReader#loadBeanDefinitions
AbstractBeanDefinitionReader#loadBeanDefinitions(String location, @Nullable Set<Resource> actualResources)
AbstractBeanDefinitionReader#loadBeanDefinitions(Resource... resources)
XmlBeanDefinitionReader#loadBeanDefinitions(Resource resource)
XmlBeanDefinitionReader#loadBeanDefinitions(EncodedResource encodedResource)
XmlBeanDefinitionReader#doLoadBeanDefinitions(InputSource inputSource, Resource resource)
XmlBeanDefinitionReader#registerBeanDefinitions(Document doc, Resource resource)
DefaultBeanDefinitionDocumentReader#registerBeanDefinitions(Document doc, XmlReaderContext readerContext)
DefaultBeanDefinitionDocumentReader#doRegisterBeanDefinitions(Element root)
DefaultBeanDefinitionDocumentReader#parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate)
解析spring中的bean
DefaultBeanDefinitionDocumentReader#parseDefaultElement
DefaultBeanDefinitionDocumentReader#processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate)
BeanDefinitionParserDelegate#parseBeanDefinitionElement(Element ele)
BeanDefinitionParserDelegate#parseBeanDefinitionElement(Element ele, @Nullable BeanDefinition containingBean)
BeanDefinitionParserDelegate#parseBeanDefinitionElement(Element ele, String beanName, @Nullable BeanDefinition containingBean)
在这里解析bean标签中定义的属性，构造函数等。
BeanDefinitionParserDelegate中包含了bean相关的所有标签
解析自定义标签
BeanDefinitionParserDelegate#parseCustomElement(Element ele)
BeanDefinitionParserDelegate#parseCustomElement(Element ele, @Nullable BeanDefinition containingBd)
NamespaceHandlerSupport#parse(Element element, ParserContext parserContext)在这里进行自定义解析。dubbo就是继承了NamespaceHandlerSupport来使用自定义标签。并且实现了BeanDefinitionParser，作为自定义解析器。
