diff --git a/framework-docs/modules/ROOT/pages/data-access/orm/jpa.adoc b/framework-docs/modules/ROOT/pages/data-access/orm/jpa.adoc index 27d2feca59..b9fc4279fc 100644 --- a/framework-docs/modules/ROOT/pages/data-access/orm/jpa.adoc +++ b/framework-docs/modules/ROOT/pages/data-access/orm/jpa.adoc @@ -88,12 +88,6 @@ You can use this option for full JPA capabilities in a Spring-based application This includes web containers such as Tomcat, stand-alone applications, and integration tests with sophisticated persistence requirements. -NOTE: If you want to specifically configure a Hibernate setup, an immediate alternative -is to set up a native Hibernate `LocalSessionFactoryBean` instead of a plain JPA -`LocalContainerEntityManagerFactoryBean`, letting it interact with JPA access code -as well as native Hibernate access code. -See xref:data-access/orm/jpa.adoc#orm-jpa-hibernate[Native Hibernate setup for JPA interaction] for details. - The `LocalContainerEntityManagerFactoryBean` gives full control over `EntityManagerFactory` configuration and is appropriate for environments where fine-grained customization is required. The `LocalContainerEntityManagerFactoryBean` @@ -187,6 +181,7 @@ and automatic propagation of the weaver to all weaver-aware beans: [source,xml,indent=0,subs="verbatim,quotes"] ---- + ... @@ -425,20 +420,20 @@ Kotlin:: ---- ====== -The `@PersistenceContext` annotation has an optional attribute called `type`, which defaults to -`PersistenceContextType.TRANSACTION`. You can use this default to receive a shared +The `@PersistenceContext` annotation has an optional attribute called `type`, which defaults +to `PersistenceContextType.TRANSACTION`. You can use this default to receive a shared `EntityManager` proxy. The alternative, `PersistenceContextType.EXTENDED`, is a completely different affair. This results in a so-called extended `EntityManager`, which is not thread-safe and, hence, must not be used in a concurrently accessed component, such as a -Spring-managed singleton bean. Extended `EntityManager` instances are only supposed to be used# +Spring-managed singleton bean. Extended `EntityManager` instances are only supposed to be used in stateful components that, for example, reside in a session, with the lifecycle of the `EntityManager` not tied to a current transaction but rather being completely up to the application. .Method- and field-level Injection **** -You can apply annotations that indicate dependency injections (such as `@PersistenceUnit` and -`@PersistenceContext`) on field or methods inside a class -- hence the expressions +You can apply annotations that indicate dependency injections (such as `@PersistenceUnit` +and `@PersistenceContext`) on field or methods inside a class -- hence the expressions "`method-level injection`" and "`field-level injection`". Field-level annotations are concise and easier to use while method-level annotations allow for further processing of the injected dependency. In both cases, the member visibility (public, protected, or private) @@ -460,12 +455,53 @@ No import of any Spring class is required. Moreover, as the JPA annotations are the injections are applied automatically by the Spring container. This is appealing from a non-invasiveness perspective and can feel more natural to JPA developers. +[[orm-jpa-dao-autowired]] +=== Implementing DAOs Based on `@Autowired` (typically with constructor-based injection) + +`@PersistenceUnit` and `@PersistenceContext` can only be declared on methods and fields. +What about providing JPA resources via constructors and other `@Autowired` injection points? + +`EntityManagerFactory` can easily be injected via constructors and `@Autowired` fields/methods +as long as the target is defined as a bean, e.g. via `LocalContainerEntityManagerFactoryBean`. +The injection point matches the original `EntityManagerFactory` definition by type as-is. + +However, an `@PersistenceContext`-style shared `EntityManager` reference is not available for +regular dependency injection out of the box. In order to make it available for type-based +matching as required by `@Autowired`, consider defining a `SharedEntityManagerBean` as a +companion for your `EntityManagerFactory` definition: + +[source,xml,indent=0,subs="verbatim,quotes"] +---- + + ... + + + + + +---- + +Alternatively, you may define an `@Bean` method based on `SharedEntityManagerCreator`: + +[source,java,indent=0,subs="verbatim,quotes"] +---- + @Bean("em") + public static EntityManager sharedEntityManager(EntityManagerFactory emf) { + return SharedEntityManagerCreator.createSharedEntityManager(emf); + } +---- + +In case of multiple persistence units, each `EntityManagerFactory` definition needs to be +accompanied by a corresponding `EntityManager` bean definition, ideally with qualifiers +that match with the distinct `EntityManagerFactory` definition in order to distinguish +the persistence units via `@Autowired @Qualifier("...")`. + [[orm-jpa-tx]] -== Spring-driven JPA transactions +== Spring-driven JPA Transactions -NOTE: We strongly encourage you to read xref:data-access/transaction/declarative.adoc[Declarative Transaction Management], if you have not -already done so, to get more detailed coverage of Spring's declarative transaction support. +NOTE: We strongly encourage you to read xref:data-access/transaction/declarative.adoc[Declarative Transaction Management], +if you have not already done so, to get more detailed coverage of Spring's declarative transaction support. The recommended strategy for JPA is local transactions through JPA's native transaction support. Spring's `JpaTransactionManager` provides many capabilities known from local @@ -478,11 +514,6 @@ to JDBC access code that accesses the same `DataSource`, provided that the regis Spring provides dialects for the EclipseLink and Hibernate JPA implementations. See the xref:data-access/orm/jpa.adoc#orm-jpa-dialect[next section] for details on the `JpaDialect` mechanism. -NOTE: As an immediate alternative, Spring's native `HibernateTransactionManager` is capable -of interacting with JPA access code, adapting to several Hibernate specifics and providing -JDBC interaction. This makes particular sense in combination with `LocalSessionFactoryBean` -setup. See xref:data-access/orm/jpa.adoc#orm-jpa-hibernate[Native Hibernate Setup for JPA Interaction] for details. - [[orm-jpa-dialect]] == Understanding `JpaDialect` and `JpaVendorAdapter`