聊聊spring data jpa的SimpleJpaRepository

序

本文主要研究一下spring data jpa的SimpleJpaRepository

JpaRepositoryImplementation

spring-data-jpa-2.1.6.RELEASE-sources.jar!/org/springframework/data/jpa/repository/support/JpaRepositoryImplementation.java

/**
 * SPI interface to be implemented by {@link JpaRepository} implementations.
 *
 * @author Oliver Gierke
 * @author Stefan Fussenegger
 */
@NoRepositoryBean
public interface JpaRepositoryImplementation<T, ID> extends JpaRepository<T, ID>, JpaSpecificationExecutor<T> {
?
 /**
 * Configures the {@link CrudMethodMetadata} to be used with the repository.
 *
 * @param crudMethodMetadata must not be {@literal null}.
 */
 void setRepositoryMethodMetadata(CrudMethodMetadata crudMethodMetadata);
}

• JpaRepositoryImplementation接口继承了JpaRepository及JpaSpecificationExecutor，它是JpaRepository接口实现类的SPI interface；它定义了setRepositoryMethodMetadata方法

SimpleJpaRepository

spring-data-jpa-2.1.6.RELEASE-sources.jar!/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

@Repository
@Transactional(readOnly = true)
public class SimpleJpaRepository<T, ID> implements JpaRepositoryImplementation<T, ID> {
?
 private static final String ID_MUST_NOT_BE_NULL = "The given id must not be null!";
?
 private final JpaEntityInformation<T, ?> entityInformation;
 private final EntityManager em;
 private final PersistenceProvider provider;
?
 private @Nullable CrudMethodMetadata metadata;
?
 /**
 * Creates a new {@link SimpleJpaRepository} to manage objects of the given {@link JpaEntityInformation}.
 *
 * @param entityInformation must not be {@literal null}.
 * @param entityManager must not be {@literal null}.
 */
 public SimpleJpaRepository(JpaEntityInformation<T, ?> entityInformation, EntityManager entityManager) {
?
 Assert.notNull(entityInformation, "JpaEntityInformation must not be null!");
 Assert.notNull(entityManager, "EntityManager must not be null!");
?
 this.entityInformation = entityInformation;
 this.em = entityManager;
 this.provider = PersistenceProvider.fromEntityManager(entityManager);
 }
?
 /**
 * Creates a new {@link SimpleJpaRepository} to manage objects of the given domain type.
 *
 * @param domainClass must not be {@literal null}.
 * @param em must not be {@literal null}.
 */
 public SimpleJpaRepository(Class<T> domainClass, EntityManager em) {
 this(JpaEntityInformationSupport.getEntityInformation(domainClass, em), em);
 }
?
 /**
 * Configures a custom {@link CrudMethodMetadata} to be used to detect {@link LockModeType}s and query hints to be
 * applied to queries.
 *
 * @param crudMethodMetadata
 */
 public void setRepositoryMethodMetadata(CrudMethodMetadata crudMethodMetadata) {
 this.metadata = crudMethodMetadata;
 }
?
 @Nullable
 protected CrudMethodMetadata getRepositoryMethodMetadata() {
 return metadata;
 }
?
 //......
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.CrudRepository#delete(java.io.Serializable)
 */
 @Transactional
 public void deleteById(ID id) {
?
 Assert.notNull(id, ID_MUST_NOT_BE_NULL);
?
 delete(findById(id).orElseThrow(() -> new EmptyResultDataAccessException(
 String.format("No %s entity with id %s exists!", entityInformation.getJavaType(), id), 1)));
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.CrudRepository#delete(java.lang.Object)
 */
 @Transactional
 public void delete(T entity) {
?
 Assert.notNull(entity, "The entity must not be null!");
 em.remove(em.contains(entity) ? entity : em.merge(entity));
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.CrudRepository#delete(java.lang.Iterable)
 */
 @Transactional
 public void deleteAll(Iterable<? extends T> entities) {
?
 Assert.notNull(entities, "The given Iterable of entities not be null!");
?
 for (T entity : entities) {
 delete(entity);
 }
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#deleteInBatch(java.lang.Iterable)
 */
 @Transactional
 public void deleteInBatch(Iterable<T> entities) {
?
 Assert.notNull(entities, "The given Iterable of entities not be null!");
?
 if (!entities.iterator().hasNext()) {
 return;
 }
?
 applyAndBind(getQueryString(DELETE_ALL_QUERY_STRING, entityInformation.getEntityName()), entities, em)
 .executeUpdate();
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.Repository#deleteAll()
 */
 @Transactional
 public void deleteAll() {
?
 for (T element : findAll()) {
 delete(element);
 }
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#deleteAllInBatch()
 */
 @Transactional
 public void deleteAllInBatch() {
 em.createQuery(getDeleteAllQueryString()).executeUpdate();
 }
?
 //......
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.CrudRepository#save(java.lang.Object)
 */
 @Transactional
 public <S extends T> S save(S entity) {
?
 if (entityInformation.isNew(entity)) {
 em.persist(entity);
 return entity;
 } else {
 return em.merge(entity);
 }
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#saveAndFlush(java.lang.Object)
 */
 @Transactional
 public <S extends T> S saveAndFlush(S entity) {
?
 S result = save(entity);
 flush();
?
 return result;
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#save(java.lang.Iterable)
 */
 @Transactional
 public <S extends T> List<S> saveAll(Iterable<S> entities) {
?
 Assert.notNull(entities, "The given Iterable of entities not be null!");
?
 List<S> result = new ArrayList<S>();
?
 for (S entity : entities) {
 result.add(save(entity));
 }
?
 return result;
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#flush()
 */
 @Transactional
 public void flush() {
 em.flush();
 }
?
 //......
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.CrudRepository#findById(java.io.Serializable)
 */
 public Optional<T> findById(ID id) {
?
 Assert.notNull(id, ID_MUST_NOT_BE_NULL);
?
 Class<T> domainType = getDomainClass();
?
 if (metadata == null) {
 return Optional.ofNullable(em.find(domainType, id));
 }
?
 LockModeType type = metadata.getLockModeType();
?
 Map<String, Object> hints = getQueryHints().withFetchGraphs(em).asMap();
?
 return Optional.ofNullable(type == null ? em.find(domainType, id, hints) : em.find(domainType, id, type, hints));
 }
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.jpa.repository.JpaRepository#getOne(java.io.Serializable)
 */
 @Override
 public T getOne(ID id) {
?
 Assert.notNull(id, ID_MUST_NOT_BE_NULL);
 return em.getReference(getDomainClass(), id);
 }
?
 /**
 * Applies the given {@link Specification} to the given {@link CriteriaQuery}.
 *
 * @param spec can be {@literal null}.
 * @param domainClass must not be {@literal null}.
 * @param query must not be {@literal null}.
 * @return
 */
 private <S, U extends T> Root<U> applySpecificationToCriteria(@Nullable Specification<U> spec, Class<U> domainClass,
 CriteriaQuery<S> query) {
?
 Assert.notNull(domainClass, "Domain class must not be null!");
 Assert.notNull(query, "CriteriaQuery must not be null!");
?
 Root<U> root = query.from(domainClass);
?
 if (spec == null) {
 return root;
 }
?
 CriteriaBuilder builder = em.getCriteriaBuilder();
 Predicate predicate = spec.toPredicate(root, query, builder);
?
 if (predicate != null) {
 query.where(predicate);
 }
?
 return root;
 }
 //......
}

• SimpleJpaRepository实现了JpaRepositoryImplementation接口，它是CrudRepository的默认实现；它的构造器都要求传入EntityManager
• 它的类上注解了@Transactional(readOnly = true)；而对deleteById、delete、deleteAll、deleteInBatch、deleteAllInBatch、save、saveAndFlush、saveAll、flush都添加了@Transactional注解
• 从各个方法的实现可以看到SimpleJpaRepository是使用EntityManager来完成具体的方法功能，对于查询功能很多都借助了applySpecificationToCriteria方法，将spring data的Specification转换为javax.persistence的CriteriaQuery

JpaRepositoryFactory

spring-data-jpa-2.1.6.RELEASE-sources.jar!/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java

public class JpaRepositoryFactory extends RepositoryFactorySupport {
?
 private final EntityManager entityManager;
 private final QueryExtractor extractor;
 private final CrudMethodMetadataPostProcessor crudMethodMetadataPostProcessor;
?
 private EntityPathResolver entityPathResolver;
 private EscapeCharacter escapeCharacter = EscapeCharacter.of('\\');
?
 /**
 * Creates a new {@link JpaRepositoryFactory}.
 *
 * @param entityManager must not be {@literal null}
 */
 public JpaRepositoryFactory(EntityManager entityManager) {
?
 Assert.notNull(entityManager, "EntityManager must not be null!");
?
 this.entityManager = entityManager;
 this.extractor = PersistenceProvider.fromEntityManager(entityManager);
 this.crudMethodMetadataPostProcessor = new CrudMethodMetadataPostProcessor();
 this.entityPathResolver = SimpleEntityPathResolver.INSTANCE;
?
 addRepositoryProxyPostProcessor(crudMethodMetadataPostProcessor);
?
 if (extractor.equals(PersistenceProvider.ECLIPSELINK)) {
 addQueryCreationListener(new EclipseLinkProjectionQueryCreationListener(entityManager));
 }
 }
?
 //......
?
 /*
 * (non-Javadoc)
 * @see org.springframework.data.repository.core.support.RepositoryFactorySupport#getTargetRepository(org.springframework.data.repository.core.RepositoryMetadata)
 */
 @Override
 protected final JpaRepositoryImplementation<?, ?> getTargetRepository(RepositoryInformation information) {
?
 JpaRepositoryImplementation<?, ?> repository = getTargetRepository(information, entityManager);
 repository.setRepositoryMethodMetadata(crudMethodMetadataPostProcessor.getCrudMethodMetadata());
?
 return repository;
 }
?
 /**
 * Callback to create a {@link JpaRepository} instance with the given {@link EntityManager}
 *
 * @param information will never be {@literal null}.
 * @param entityManager will never be {@literal null}.
 * @return
 */
 protected JpaRepositoryImplementation<?, ?> getTargetRepository(RepositoryInformation information,
 EntityManager entityManager) {
?
 JpaEntityInformation<?, Serializable> entityInformation = getEntityInformation(information.getDomainType());
 Object repository = getTargetRepositoryViaReflection(information, entityInformation, entityManager);
?
 Assert.isInstanceOf(JpaRepositoryImplementation.class, repository);
?
 return (JpaRepositoryImplementation<?, ?>) repository;
 }
?
 //......
}

• JpaRepositoryFactory的getTargetRepository会根据RepositoryInformation创建JpaRepositoryImplementation，这里默认创建的是SimpleJpaRepository实例

RepositoryFactorySupport

spring-data-commons-2.1.6.RELEASE-sources.jar!/org/springframework/data/repository/core/support/RepositoryFactorySupport.java

public abstract class RepositoryFactorySupport implements BeanClassLoaderAware, BeanFactoryAware {
?
 //......
?
 /**
 * Returns a repository instance for the given interface backed by an instance providing implementation logic for
 * custom logic.
 *
 * @param repositoryInterface must not be {@literal null}.
 * @param fragments must not be {@literal null}.
 * @return
 * @since 2.0
 */
 @SuppressWarnings({ "unchecked" })
 public <T> T getRepository(Class<T> repositoryInterface, RepositoryFragments fragments) {
?
 if (LOG.isDebugEnabled()) {
 LOG.debug("Initializing repository instance for {}…", repositoryInterface.getName());
 }
?
 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));
?
 T repository = (T) result.getProxy(classLoader);
?
 if (LOG.isDebugEnabled()) {
 LOG.debug("Finished creation of repository instance for {}.", repositoryInterface.getName());
 }
?
 return repository;
 }
?
 //......
}

• RepositoryFactorySupport的getRepository方法在调用子类的getTargetRepository创建SimpleJpaRepository实例之后，会对其进行proxy，设置其接口为用户定义的dao接口、Repository、TransactionalProxy，并添加了SurroundingTransactionDetectorMethodInterceptor、DefaultMethodInvokingMethodInterceptor、QueryExecutorMethodInterceptor、ImplementationMethodExecutionInterceptor等MethodInterceptor，最后生成最终的实现类

小结

• JpaRepositoryImplementation接口继承了JpaRepository及JpaSpecificationExecutor，它是JpaRepository接口实现类的SPI interface；它定义了setRepositoryMethodMetadata方法
• SimpleJpaRepository实现了JpaRepositoryImplementation接口，它是CrudRepository的默认实现；它的构造器都要求传入EntityManager；从各个方法的实现可以看到SimpleJpaRepository是使用EntityManager来完成具体的方法功能，对于查询功能很多都借助了applySpecificationToCriteria方法，将spring data的Specification转换为javax.persistence的CriteriaQuery
• JpaRepositoryFactory的getTargetRepository会根据RepositoryInformation创建JpaRepositoryImplementation，这里默认创建的是SimpleJpaRepository实例；RepositoryFactorySupport的getRepository方法在调用子类的getTargetRepository创建SimpleJpaRepository实例之后，会对其进行proxy，设置其接口为用户定义的dao接口、Repository、TransactionalProxy，并添加了SurroundingTransactionDetectorMethodInterceptor、DefaultMethodInvokingMethodInterceptor、QueryExecutorMethodInterceptor、ImplementationMethodExecutionInterceptor等MethodInterceptor，最后生成最终的实现类

doc

• SimpleJpaRepository
• SimpleJpaRepository.java
• Customizing Spring Data JPA Repository
• Spring Data JPA – Adding a Method in All Repositories
• Spring Data JPA Tutorial: Adding Custom Methods to All Repositories