JPA provider vs. dialect vs. vendor in the Spring contaniner configuration
Will try to explain it to you line by line:
<bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
//Should ideally be
<bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
- This bean defines the jpaDialect that you are going to use. JpaDialect is an interface encapsulates certain functionality that standard JPA 1.0 does not offer, such as access to the underlying JDBC Connection. This strategy is mainly intended for standalone usage of a JPA provider; most of its functionality is not relevant when running with JTA transactions. Also allows for the provision of value-added methods for portable yet more capable EntityManager and EntityManagerFactory subinterfaces offered by Spring.
- Since you have provided the class as
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
, this allowsSpring
to plug in vendor-specific behavior into Spring'sEntityManagerFactory
creators and it serves as single configuration point for all vendor-specific properties.It's a custom implementation of spring's ownJpaVendorAdapter
.
For the second bean where you have declared:
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory"ref="entityManagerFactory"/>
<property name="jpaDialect"ref="jpaDialect"/>
</bean>
- You tell 'Spring' to configure a
transactionManager
whose properties areentityManagerFactory
andjpaDialect
. Since these properties have to specific tohibernate
these are set according. TheentityManagerFactory
andjpaDialect
are now set specifically tohibernate
(or Vendor).
As for the third bean
<property name="jpaDialect"ref="jpaDialect"/>
...
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
...
<provider>org.hibernate.ejb.HibernatePersistence</provider>
The <provider>
tells spring to use the hibernate
provider and the class org.hibernate.ejb.HibernatePersistence
is Hibernate EJB3 persistence provider implementation.
In short, you need to configure these in order to tell spring which ORM's functionality should be used.
The reason that your application worked with configuring just persistence and provider is because the vendor adapter is automatically passed the persistence provided i.e. HibernatePersistence
via the getPersistenceProvider
in JpaVendorAdapter
.
Tinker around the documentation to understand how these classes are interlinked.
EDIT : As pointed out by @TheKojuEffect , the first bean should ideally be in the form of :
<bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
Thanks. Missed the vendorAdapter
.
You can refer :
Hope it helps. :)
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Alexandr
Updated on October 02, 2022Comments
-
Alexandr over 1 year
Example of spring configuration file:
<bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory"ref="entityManagerFactory"/> <property name="jpaDialect"ref="jpaDialect"/> </bean> <bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" /> </property> .... </bean>
and the persistence.xml jpa file:
<persistence-unit name="EmployeeService"> <provider>org.hibernate.ejb.HibernatePersistence</provider> </persistence-unit>
As you can see the jpa provider-related information is set 3 times. In transaction manager bean, entity manager factory bean and in the persistence unit configuration:
<property name="jpaDialect"ref="jpaDialect"/> ... <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" /> </property> ... <provider>org.hibernate.ejb.HibernatePersistence</provider>
But actually in my project I configured only the persistence unit with provider. And it worked.
So my question is what's the difference between provider, dialect and vendor options? Must I set all of them or, I can skip some of them? Can I set, for example as a vendor for EntityMangerFactory - Hibernate, as a dialect in transaction manager - Eclipse and as a provider in the persistence unit configuration - something else, TopLink, for example.
It's no clear to me. Please explain.
-
TheKojuEffect over 10 yearsNice explanation but I think you've done mistake in your answer. In first bean
jpaDialect
, I think you meantjpaVendorAdapter
. It would be better if you correct your answer. -
Alexandr over 10 yearsThanks for the reply. I've looked through the HibernateJpaVendorAdapter and found getJpaDialect() and getPersistenceProvider() methods. I think it would be correct to configure entity manager factory with HibernateJpaVendorAdapter only. And it'll be enough cause both jpa dialect and jpa provider can be received from the adapter class.