当项目中存在 org.springframework.data.jpa.repository.JpaRepository
类,并且已经注入过数据源 javax.sql.DataSource
,同时没有注入过 org.springframework.data.jpa.repository.config.JpaRepositoryConfigExtension
和 org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean
时,会通过 @Import
注解导入 org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfigureRegistrar
,由它完成对JPA的支持。 JpaRepositoriesAutoConfigureRegistrar
又继承自 AbstractRepositoryConfigurationSourceSupport
。来看下 AbstractRepositoryConfigurationSourceSupport
的具体内容。
public abstract class AbstractRepositoryConfigurationSourceSupport implements BeanFactoryAware, ImportBeanDefinitionRegistrar, ResourceLoaderAware, EnvironmentAware { private ResourceLoader resourceLoader; private BeanFactory beanFactory; private Environment environment; @Override public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { new RepositoryConfigurationDelegate(getConfigurationSource(registry), this.resourceLoader, this.environment).registerRepositoriesIn(registry, getRepositoryConfigurationExtension()); } ...... } 复制代码
可以看出,到 AbstractRepositoryConfigurationSourceSupport
对 Repository
的Bean进行了定义。下面来具体看看Repositoryd的创建。
我们先来看下 RepositoryConfigurationDelegate
的 registerRepositoriesIn
方法。
public List<BeanComponentDefinition> registerRepositoriesIn(BeanDefinitionRegistry registry, RepositoryConfigurationExtension extension) { extension.registerBeansForRoot(registry, configurationSource); RepositoryBeanDefinitionBuilder builder = new RepositoryBeanDefinitionBuilder(registry, extension, resourceLoader, environment); List<BeanComponentDefinition> definitions = new ArrayList<>(); for (RepositoryConfiguration<? extends RepositoryConfigurationSource> configuration : extension .getRepositoryConfigurations(configurationSource, resourceLoader, inMultiStoreMode)) { BeanDefinitionBuilder definitionBuilder = builder.build(configuration); extension.postProcess(definitionBuilder, configurationSource); if (isXml) { extension.postProcess(definitionBuilder, (XmlRepositoryConfigurationSource) configurationSource); } else { extension.postProcess(definitionBuilder, (AnnotationRepositoryConfigurationSource) configurationSource); } AbstractBeanDefinition beanDefinition = definitionBuilder.getBeanDefinition(); String beanName = configurationSource.generateBeanName(beanDefinition); ...... beanDefinition.setAttribute(FACTORY_BEAN_OBJECT_TYPE, configuration.getRepositoryInterface()); registry.registerBeanDefinition(beanName, beanDefinition); definitions.add(new BeanComponentDefinition(beanDefinition, beanName)); } return definitions; } 复制代码
到这里其实只是创建了repository的实体Bean的BeanDefinition。前期准备做好了,实际创建repository是在 RepositoryFactorySupport
的getRepository方法。
public <T> T getRepository(Class<T> repositoryInterface, RepositoryFragments fragments) { Assert.notNull(repositoryInterface, "Repository interface must not be null!"); Assert.notNull(fragments, "RepositoryFragments must not be null!"); RepositoryMetadata metadata = getRepositoryMetadata(repositoryInterface); RepositoryComposition composition = getRepositoryComposition(metadata, fragments); RepositoryInformation information = getRepositoryInformation(metadata, composition); validate(information, composition); Object target = getTargetRepository(information); // Create proxy ProxyFactory result = new ProxyFactory(); result.setTarget(target); result.setInterfaces(repositoryInterface, Repository.class, TransactionalProxy.class); if (MethodInvocationValidator.supports(repositoryInterface)) { result.addAdvice(new MethodInvocationValidator()); } result.addAdvice(SurroundingTransactionDetectorMethodInterceptor.INSTANCE); result.addAdvisor(ExposeInvocationInterceptor.ADVISOR); postProcessors.forEach(processor -> processor.postProcess(result, information)); result.addAdvice(new DefaultMethodInvokingMethodInterceptor()); ProjectionFactory projectionFactory = getProjectionFactory(classLoader, beanFactory); result.addAdvice(new QueryExecutorMethodInterceptor(information, projectionFactory)); composition = composition.append(RepositoryFragment.implemented(target)); result.addAdvice(new ImplementationMethodExecutionInterceptor(composition)); return (T) result.getProxy(classLoader); } 复制代码
首先去获取我们写的repository接口的元数据,包括实体的ID类型,管理的实体类型等。接着获取repository的组合,主要包含repository的方法信息。然后再根据它俩的组合得到一个target。这个target其实就是一个SimpleJpaRepository实体,里面包含了一些通用的方法。只有这些还不够,于是有了后面的代理工厂,对这个target进行进一步处理。包括事务支持,异常处理和SQL创造等。我们主要看一下SQL创建。创建的方法在 DeclaredQueryLookupStrategy
的 resolveQuery
中。
protected RepositoryQuery resolveQuery(JpaQueryMethod method, EntityManager em, NamedQueries namedQueries) { RepositoryQuery query = JpaQueryFactory.INSTANCE.fromQueryAnnotation(method, em, evaluationContextProvider); if (null != query) { return query; } query = JpaQueryFactory.INSTANCE.fromProcedureAnnotation(method, em); if (null != query) { return query; } String name = method.getNamedQueryName(); if (namedQueries.hasQuery(name)) { return JpaQueryFactory.INSTANCE.fromMethodWithQueryString(method, em, namedQueries.getQuery(name), evaluationContextProvider); } query = NamedQuery.lookupFrom(method, em); if (null != query) { return query; } throw new IllegalStateException( String.format("Did neither find a NamedQuery nor an annotated query for method %s!", method)); } 复制代码
该方法的逻辑是先找有注解的,这个包括 @Query
和 @Procedure
,接着是根据关键字创建,然后是通用方法。