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這篇文章給大家分享的是有關(guān)Spring事務(wù)開啟原理的示例分析的內(nèi)容。小編覺得挺實(shí)用的,因此分享給大家做個(gè)參考,一起跟隨小編過來看看吧。
在事務(wù)配置類上聲明@EnableTransactionManagement注解開啟事務(wù)
在事務(wù)配置類上定義數(shù)據(jù)源
在事務(wù)配置類上定義事務(wù)管理器
在相關(guān)類或者方法上使用@Transactional聲明事務(wù)
代碼如下:
@Configuration @EnableTransactionManagement public class RootConfig{ @Bean public DataSource dataSource(){ DruidDataSource dataSource = new DruidDataSource(); dataSource.setXXX(); ... return dataSource; } @Bean public PlatfromTransactionManager txManager(){ return new DataSourceTransactionManager(dataSource()); } }
@Service public class UserService{ @Autowired private UserRepository userRepository; @Transactional public void addUser(User user){ userRepository.save(user); } }
@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(shí)現(xiàn)其注入,而TransactionManagementConfigurationSelector又主要使用selectImport方法來實(shí)現(xiàn)其注入,代碼如下:
@Override public 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(jù)AdviceMode返回不同的類型,默認(rèn)是AdviceMode.PROXY。 String[] imports = selectImports(adviceMode); if (imports == null) { throw new IllegalArgumentException(String.format("Unknown AdviceMode: '%s'", adviceMode)); } return imports; } @Override protected 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(diǎn)為根據(jù)AdviceMode選擇創(chuàng)建不同的bean,AdviceMode的默認(rèn)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(shí)現(xiàn)了ImportBeanDefinitionRegistrar,那在創(chuàng)建bean的時(shí)候會(huì)調(diào)用registerBeanDefinitions方法。registerBeanDefinitions方法的實(shí)現(xiàn):
@Override public 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(huì)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(cè)InfrastructureAdvisorAutoProxyCreator來啟動(dòng)Spring Aop。
接下來再看ProxyTransactionManagementConfiguration的作用,代碼如下:
@Configuration public 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(gè)配置文件,注冊(cè)了三個(gè)bean,BeanFactoryTransactionAttributeSourceAdvisor、AnnotationTransactionAttributeSource、TransactionInterceptor,而這三個(gè)類分別繼承Advisor、Advice和Pointcut。即切面所需組件。
感謝各位的閱讀!關(guān)于“Spring事務(wù)開啟原理的示例分析”這篇文章就分享到這里了,希望以上內(nèi)容可以對(duì)大家有一定的幫助,讓大家可以學(xué)到更多知識(shí),如果覺得文章不錯(cuò),可以把它分享出去讓更多的人看到吧!
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