在事務配置類上聲明@EnableTransactionManagement注解開啟事務 在事務配置類上定義數據源 在事務配置類上定義事務管理器 在相關類或者方法上使用@Transactional聲明事務

代碼如下：

@Configuration@EnableTransactionManagementpublic class RootConfig{ @Bean public DataSource dataSource(){ DruidDataSource dataSource = new DruidDataSource(); dataSource.setXXX(); ... return dataSource; } @Bean public PlatfromTransactionManager txManager(){ return new DataSourceTransactionManager(dataSource()); }}

@Servicepublic class UserService{ @Autowired private UserRepository userRepository; @Transactional public void addUser(User user){ userRepository.save(user); }}@EnableTransactionManagement開啟事務原理解析

@EnableTransactionManagement源碼如下：

@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Import(TransactionManagementConfigurationSelector.class)public @interface EnableTransactionManagement { boolean proxyTargetClass() default false; AdviceMode mode() default AdviceMode.PROXY; int order() default Ordered.LOWEST_PRECEDENCE;}

可以看到，@EnableTransactionManagement接口類主要Import了TransactionManagementConfigurationSelector來實現其注入，而TransactionManagementConfigurationSelector又主要使用selectImport方法來實現其注入，代碼如下：

@Overridepublic final String[] selectImports(AnnotationMetadata importingClassMetadata) { Class<?> annoType = GenericTypeResolver.resolveTypeArgument(getClass(), AdviceModeImportSelector.class); AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(importingClassMetadata, annoType); if (attributes == null) { throw new IllegalArgumentException(String.format( '@%s is not present on importing class ’%s’ as expected', annoType.getSimpleName(), importingClassMetadata.getClassName())); } AdviceMode adviceMode = attributes.getEnum(this.getAdviceModeAttributeName()); //根據AdviceMode返回不同的類型，默認是AdviceMode.PROXY。 String[] imports = selectImports(adviceMode); if (imports == null) { throw new IllegalArgumentException(String.format('Unknown AdviceMode: ’%s’', adviceMode)); } return imports;}@Overrideprotected String[] selectImports(AdviceMode adviceMode) { switch (adviceMode) { case PROXY: return new String[] {AutoProxyRegistrar.class.getName(), ProxyTransactionManagementConfiguration.class.getName()}; case ASPECTJ: return new String[] {TransactionManagementConfigUtils.TRANSACTION_ASPECT_CONFIGURATION_CLASS_NAME}; default: return null; }}

其中主要功能點為根據AdviceMode選擇創建不同的bean，AdviceMode的默認代理方式是PROXY，jdk代理。所以返回的是AutoProxyRegistrar和ProxyTransactionManagementConfiguration。

我們先分析AutoProxyRegistrar，AutoProxyRegistrar實現了ImportBeanDefinitionRegistrar，那在創建bean的時候會調用registerBeanDefinitions方法。registerBeanDefinitions方法的實現：

@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { boolean candidateFound = false; Set<String> annoTypes = importingClassMetadata.getAnnotationTypes(); for (String annoType : annoTypes) { AnnotationAttributes candidate = AnnotationConfigUtils.attributesFor(importingClassMetadata, annoType); 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; //只有@EnableTransactionManagement注解才會走到這里 if (mode == AdviceMode.PROXY) { AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry); if ((Boolean) proxyTargetClass) { AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry); return; } } } } //...}public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) { return registerOrEscalateApcAsRequired(InfrastructureAdvisorAutoProxyCreator.class, registry, source);}

可以看到，它通過注冊InfrastructureAdvisorAutoProxyCreator來啟動Spring Aop。

接下來再看ProxyTransactionManagementConfiguration的作用，代碼如下：

@Configurationpublic class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration { @Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME) @Role(BeanDefinition.ROLE_INFRASTRUCTURE) public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() { BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor(); advisor.setTransactionAttributeSource(transactionAttributeSource()); advisor.setAdvice(transactionInterceptor()); advisor.setOrder(this.enableTx.<Integer>getNumber('order')); return advisor; } @Bean @Role(BeanDefinition.ROLE_INFRASTRUCTURE) public TransactionAttributeSource transactionAttributeSource() { return new AnnotationTransactionAttributeSource(); } @Bean @Role(BeanDefinition.ROLE_INFRASTRUCTURE) public TransactionInterceptor transactionInterceptor() { TransactionInterceptor interceptor = new TransactionInterceptor(); interceptor.setTransactionAttributeSource(transactionAttributeSource()); if (this.txManager != null) { interceptor.setTransactionManager(this.txManager); } return interceptor; }}

ProxyTransactionManagementConfiguration是一個配置文件，注冊了三個bean，BeanFactoryTransactionAttributeSourceAdvisor、AnnotationTransactionAttributeSource、TransactionInterceptor，而這三個類分別繼承Advisor、Advice和Pointcut。即切面所需組件。

總結

@EnableTransactionManagement利用AutoProxyRegistrar啟動Spring Aop,使用ProxyTransactionManagementConfiguration配置對應切面部件。

以上就是Spring事務的簡單實現步驟的詳細內容，更多關于Spring事務實現步驟的資料請關注好吧啦網其它相關文章！