一. @EnableTransactionManagement

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(TransactionManagementConfigurationSelector.class)
public @interface EnableTransactionManagement {

@EnableTransactionManagement 注解使⽤ @Import 标签引⼊了

TransactionManagementConfifigurationSelector 类，这个类⼜向容器中导⼊了两个重要的组件

二. 加载事务控制组件

AutoProxyRegistrar

AutoProxyRegistrar 类的 registerBeanDefifinitions ⽅法中⼜注册了⼀个组件

进⼊ AopConfifigUtils.registerAutoProxyCreatorIfNecessary ⽅法

发现最终，注册了⼀个叫做 InfrastructureAdvisorAutoProxyCreator 的 Bean ，⽽这个类是

AbstractAutoProxyCreator 的⼦类，实现了 SmartInstantiationAwareBeanPostProcessor 接⼝

public class InfrastructureAdvisorAutoProxyCreator extends
AbstractAdvisorAutoProxyCreator
public abstract class AbstractAdvisorAutoProxyCreator extends
AbstractAutoProxyCreator
public abstract class AbstractAutoProxyCreator extends
ProxyProcessorSupport
 implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware

继承体系结构图如下

它实现了 SmartInstantiationAwareBeanPostProcessor ，说明这是⼀个后置处理器，⽽且跟

spring AOP 开启 @EnableAspectJAutoProxy 时注册的 AnnotationAwareAspectJProxyCreator 实

现的是同⼀个接⼝，所以说，声明式事务是 springAOP 思想的⼀种应⽤

ProxyTransactionManagementConfifiguration 组件

@Configuration
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {

	@Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() {
		// 事务增强器
		BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();
		// 向事务增强器中注入 属性解析器 transactionAttributeSource
		advisor.setTransactionAttributeSource(transactionAttributeSource());
		// 向事务增强器中注入 事务拦截器 transactionInterceptor
		advisor.setAdvice(transactionInterceptor());
		if (this.enableTx != null) {
			advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
		}
		return advisor;
	}

	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	// 属性解析器 transactionAttributeSource
	public TransactionAttributeSource transactionAttributeSource() {
		return new AnnotationTransactionAttributeSource();
	}

	@Bean
	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
	// 事务拦截器 transactionInterceptor
	public TransactionInterceptor transactionInterceptor() {
		TransactionInterceptor interceptor = new TransactionInterceptor();
		interceptor.setTransactionAttributeSource(transactionAttributeSource());
		if (this.txManager != null) {
			interceptor.setTransactionManager(this.txManager);
		}
		return interceptor;
	}

ProxyTransactionManagementConfifiguration 是⼀个容器配置类，注册了⼀个组件

transactionAdvisor ，称为事务增强器，然后在这个事务增强器中⼜注⼊了两个属性：

transactionAttributeSource ，即属性解析器 transactionAttributeSource 和事务拦截器

transactionInterceptor

属性解析器 AnnotationTransactionAttributeSource 部分源码如下