根据自定义标签的使用规则，可以知道会执行AnnotationDrivenBeanDefinitionParser的parse
@Override public BeanDefinition parse(Element element, ParserContext parserContext) { registerTransactionalEventListenerFactory(parserContext); String mode = element.getAttribute("mode"); if ("aspectj".equals(mode)) { // mode="aspectj" registerTransactionAspect(element, parserContext); } else { // mode="proxy" AopAutoProxyConfigurer.configureAutoProxyCreator(element, parserContext); } return null; }
在解析中存在对于mode属性的判断，根据配置，选择以动态织入还是静态织入。以下分析以proxy方式织入。
注册InfrastructureAdvisorAutoProxyCreator
private static class AopAutoProxyConfigurer { public static void configureAutoProxyCreator(Element element, ParserContext parserContext) { AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element); //TRANSACTION_ADVISOR_BEAN_NAME ="org.springframework.transaction.config.internalTransactionAdvisor"; String txAdvisorBeanName = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME; if (!parserContext.getRegistry().containsBeanDefinition(txAdvisorBeanName)) { Object eleSource = parserContext.extractSource(element); //创建TransactionAttributeSource的bean RootBeanDefinition sourceDef = new RootBeanDefinition( "org.springframework.transaction.annotation.AnnotationTransactionAttributeSource"); sourceDef.setSource(eleSource); sourceDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); //注册bean,并使用Spring中的定义规则生成beanname String sourceName = parserContext.getReaderContext().registerWithGeneratedName(sourceDef); //创建TransactionInterceptor的bean RootBeanDefinition interceptorDef = new RootBeanDefinition(TransactionInterceptor.class); interceptorDef.setSource(eleSource); interceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); registerTransactionManager(element, interceptorDef); interceptorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName)); //注册bean,并使用Spring中的定义规则生成beanname String interceptorName = parserContext.getReaderContext().registerWithGeneratedName(interceptorDef); //如果配置了order属性，则加入到bean中 //创建TransactionAttributeSourceAdvisor的bean RootBeanDefinition advisorDef = new RootBeanDefinition(BeanFactoryTransactionAttributeSourceAdvisor.class); advisorDef.setSource(eleSource); advisorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); //将sourceName的bean注入advisorDef的transactionAttributeSource属性中 advisorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName)); //将interceptorName的bean注入advisorDef的adviceBeanName属性中 advisorDef.getPropertyValues().add("adviceBeanName", interceptorName); if (element.hasAttribute("order")) { advisorDef.getPropertyValues().add("order", element.getAttribute("order")); } parserContext.getRegistry().registerBeanDefinition(txAdvisorBeanName, advisorDef); //创建CompositeComponentDefinition CompositeComponentDefinition compositeDef = new CompositeComponentDefinition(element.getTagName(), eleSource); compositeDef.addNestedComponent(new BeanComponentDefinition(sourceDef, sourceName)); compositeDef.addNestedComponent(new BeanComponentDefinition(interceptorDef, interceptorName)); compositeDef.addNestedComponent(new BeanComponentDefinition(advisorDef, txAdvisorBeanName)); parserContext.registerComponent(compositeDef); } } }
上面的代码注册了代理类及三个bean，这三个bean支撑了整个的事务功能，那么这三个bean是怎么组织起来的呢？
其中的两个bean被注册到了一个名为advisorDef的bean中，advisorDef使用BeanFactoryTransactionAttributeSourceAdvisor作为其class属性。也就是说BeanFactoryTransactionAttributeSourceAdvisor代表着当前bean。
上面函数configureAutoProxyCreator中的第一句貌似很简单但却是很重要的代码：
AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element);
public static void registerAutoProxyCreatorIfNecessary( ParserContext parserContext, Element sourceElement) { BeanDefinition beanDefinition = AopConfigUtils.registerAutoProxyCreatorIfNecessary( parserContext.getRegistry(), parserContext.extractSource(sourceElement)); useClassProxyingIfNecessary(parserContext.getRegistry(), sourceElement); registerComponentIfNecessary(beanDefinition, parserContext); }
对于解析来的代码流程AOP中已经有所分析，上面的两个函数主要目的是注册了InfrastructureAdvisorAutoProxyCreator类型的bean，那么注册这个类的目的是什么呢？
public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) { return registerOrEscalateApcAsRequired(InfrastructureAdvisorAutoProxyCreator.class, registry, source); }
