玉溪网站建设制作,凌风wordpress百度云,徐州建站公司模板,黑龙江建设厅网站首页springBoot事务基本原理是基于spring的BeanPostProcessor#xff0c;在springBoot中事务使用方式为#xff1a;
一、在启动类上添加注解#xff1a;EnableTransactionManagement
二、在需要事务的接口上添加注解#xff1a;Transactional
基本原理#xff1a;
注解在springBoot中事务使用方式为
一、在启动类上添加注解EnableTransactionManagement
二、在需要事务的接口上添加注解Transactional
基本原理
注解EnableTransactionManagement 存在一个import :
Import(TransactionManagementConfigurationSelector.class) TransactionManagementConfigurationSelector 继承树为 由此可以看到TransactionManagementConfigurationSelector 继承自
AdviceModeImportSelector
该类又实现了
ImportSelector 重写了接口 protected String[] selectImports(AdviceMode adviceMode) {switch (adviceMode) {case PROXY:return new String[] {AutoProxyRegistrar.class.getName(),ProxyTransactionManagementConfiguration.class.getName()};case ASPECTJ:return new String[] {determineTransactionAspectClass()};default:return null;}} AdviceMode 默认属性为PROXY TransactionManagementConfigurationSelector:又导入了两个类分别为①AutoProxyRegistrar②ProxyTransactionManagementConfiguration
分析①AutoProxyRegistrar 该类实现接口ImportBeanDefinitionRegistrar通过registerBeanDefinitions 向容器中注入了组件添加后置处理器 public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {boolean candidateFound false;SetString annTypes importingClassMetadata.getAnnotationTypes();for (String annType : annTypes) {AnnotationAttributes candidate AnnotationConfigUtils.attributesFor(importingClassMetadata, annType);if (candidate null) {continue;}Object mode candidate.get(mode);Object proxyTargetClass candidate.get(proxyTargetClass);if (mode ! null proxyTargetClass ! null AdviceMode.class mode.getClass() Boolean.class proxyTargetClass.getClass()) {candidateFound true;if (mode AdviceMode.PROXY) {//注册自动代理AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry);if ((Boolean) proxyTargetClass) {AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);return;}}}}if (!candidateFound logger.isInfoEnabled()) {String name getClass().getSimpleName();logger.info(String.format(%s was imported but no annotations were found having both mode and proxyTargetClass attributes of type AdviceMode and boolean respectively. This means that auto proxy creator registration and configuration may not have occurred as intended, and components may not be proxied as expected. Check to ensure that %s has been Imported on the same class where these annotations are declared; otherwise remove the import of %s altogether., name, name, name));}}
向容器注入组件InfrastructureAdvisorAutoProxyCreator private static BeanDefinition registerOrEscalateApcAsRequired(Class? cls, BeanDefinitionRegistry registry, Nullable Object source) {Assert.notNull(registry, BeanDefinitionRegistry must not be null);if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {BeanDefinition apcDefinition registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);if (!cls.getName().equals(apcDefinition.getBeanClassName())) {int currentPriority findPriorityForClass(apcDefinition.getBeanClassName());int requiredPriority findPriorityForClass(cls);if (currentPriority requiredPriority) {apcDefinition.setBeanClassName(cls.getName());}}return null;}//注册一个BeanDefinitionRootBeanDefinition beanDefinition new RootBeanDefinition(cls);beanDefinition.setSource(source);beanDefinition.getPropertyValues().add(order, Ordered.HIGHEST_PRECEDENCE);beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);return beanDefinition;}
主要添加一个bean的后置处理器InfrastructureAdvisorAutoProxyCreator Nullablepublic static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Nullable Object source) {return registerOrEscalateApcAsRequired(InfrastructureAdvisorAutoProxyCreator.class, registry, source);}
InfrastructureAdvisorAutoProxyCreator 继承类图可见
SmartInstantiationAwareBeanPostProcessor -》InstantiationAwareBeanPostProcessor-》BeanPostProcessor在类AbstractAutoProxyCreator 重写了postProcessBeforeInitialization和postProcessAfterInitialization接口其中after接口定义如下 public Object postProcessAfterInitialization(Nullable Object bean, String beanName) {if (bean ! null) {Object cacheKey getCacheKey(bean.getClass(), beanName);if (this.earlyProxyReferences.remove(cacheKey) ! bean) {return wrapIfNecessary(bean, beanName, cacheKey);}}return bean;}//创建代理对象//参数当前beanbean名称protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {if (StringUtils.hasLength(beanName) this.targetSourcedBeans.contains(beanName)) {return bean;}if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {return bean;}if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;}//判断是否需要创建代理对象如果需要则创建代理对象.Object[] specificInterceptors getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);if (specificInterceptors ! DO_NOT_PROXY) {this.advisedBeans.put(cacheKey, Boolean.TRUE);Object proxy createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));this.proxyTypes.put(cacheKey, proxy.getClass());return proxy;}this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;} ②ProxyTransactionManagementConfiguration 是一个配置类用于注册启用基于代理的注释驱动的事务管理所必需的 Spring 基础结构 bean。注册了三个bean分别是
1BeanFactoryTransactionAttributeSourceAdvisor事务通知器 Bean(name TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)Role(BeanDefinition.ROLE_INFRASTRUCTURE)public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor(TransactionAttributeSource transactionAttributeSource, TransactionInterceptor transactionInterceptor) {BeanFactoryTransactionAttributeSourceAdvisor advisor new BeanFactoryTransactionAttributeSourceAdvisor();advisor.setTransactionAttributeSource(transactionAttributeSource);advisor.setAdvice(transactionInterceptor);if (this.enableTx ! null) {advisor.setOrder(this.enableTx.IntegergetNumber(order));}return advisor;}
2TransactionAttributeSource一个事务属性相关来源知道如何获取事务属性无论是从配置、源代码级别的元数据属性如注释还是其他任何位置解析注解的属性 BeanRole(BeanDefinition.ROLE_INFRASTRUCTURE)public TransactionAttributeSource transactionAttributeSource() {return new AnnotationTransactionAttributeSource();}
3TransactionInterceptor事务拦截器具体执行事务的相关内容就在此处。 BeanRole(BeanDefinition.ROLE_INFRASTRUCTURE)public TransactionInterceptor transactionInterceptor(TransactionAttributeSource transactionAttributeSource) {TransactionInterceptor interceptor new TransactionInterceptor();interceptor.setTransactionAttributeSource(transactionAttributeSource);if (this.txManager ! null) {interceptor.setTransactionManager(this.txManager);}return interceptor;}
执行事务操作就在这个拦截器里面 public Object invoke(MethodInvocation invocation) throws Throwable {// Work out the target class: may be {code null}.// The TransactionAttributeSource should be passed the target class// as well as the method, which may be from an interface.Class? targetClass (invocation.getThis() ! null ? AopUtils.getTargetClass(invocation.getThis()) : null);// Adapt to TransactionAspectSupports invokeWithinTransaction...return invokeWithinTransaction(invocation.getMethod(), targetClass, new CoroutinesInvocationCallback() {OverrideNullable//重点在这咧public Object proceedWithInvocation() throws Throwable {return invocation.proceed();}Overridepublic Object getTarget() {return invocation.getThis();}Overridepublic Object[] getArguments() {return invocation.getArguments();}});}
执行事务调用代码 PlatformTransactionManager ptm asPlatformTransactionManager(tm);final String joinpointIdentification methodIdentification(method, targetClass, txAttr);if (txAttr null || !(ptm instanceof CallbackPreferringPlatformTransactionManager)) {// Standard transaction demarcation with getTransaction and commit/rollback calls.//创建一个事务TransactionInfo txInfo createTransactionIfNecessary(ptm, txAttr, joinpointIdentification);Object retVal;try {// This is an around advice: Invoke the next interceptor in the chain.// This will normally result in a target object being invoked.//执行被代理的方法retVal invocation.proceedWithInvocation();}catch (Throwable ex) {// target invocation exception//如果有异常就执行回滚completeTransactionAfterThrowing(txInfo, ex);throw ex;}finally {//清空事务cleanupTransactionInfo(txInfo);}if (retVal ! null vavrPresent VavrDelegate.isVavrTry(retVal)) {// Set rollback-only in case of Vavr failure matching our rollback rules...TransactionStatus status txInfo.getTransactionStatus();if (status ! null txAttr ! null) {retVal VavrDelegate.evaluateTryFailure(retVal, txAttr, status);}}//提交事务commitTransactionAfterReturning(txInfo);return retVal;}
以上就是spring事务的简单基本原理不过分深究。核心的核心就是spring的后置处理机制。包括BeanFactoryPostProcessor和BeanPostProcessor这两个关键的后置处理机制在初始化前后对bean进行扩展处理。
