The Persistence Layer with Spring 3.1 and JPA

1. Overview

This is tutorial shows how to set up Spring with JPA, using Hibernate as a persistence provider.

For a step by step introduction about setting up the Spring context using Java based configuration and the basic Maven pom for the project, see this article.

2. The JPA Spring Configuration with Java

To use JPA in a Spring project, the EntityManager needs to be set up.

This is the main part of the configuration – and it is done via a Spring factory bean – either the simpler LocalEntityManagerFactoryBean or the more flexible LocalContainerEntityManagerFactoryBean. The latter option is used here, so that additional properties can be configured on it:

@Configuration
@EnableTransactionManagement
public class PersistenceJPAConfig{

   @Bean
   public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() {
      LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
      em.setDataSource(dataSource());
      em.setPackagesToScan(new String[] { "org.baeldung.persistence.model" });

      JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
      em.setJpaVendorAdapter(vendorAdapter);
      em.setJpaProperties(additionalProperties());

      return em;
   }

   @Bean
   public DataSource dataSource(){
      DriverManagerDataSource dataSource = new DriverManagerDataSource();
      dataSource.setDriverClassName("com.mysql.jdbc.Driver");
      dataSource.setUrl("jdbc:mysql://localhost:3306/spring_jpa");
      dataSource.setUsername( "tutorialuser" );
      dataSource.setPassword( "tutorialmy5ql" );
      return dataSource;
   }

   @Bean
   public PlatformTransactionManager transactionManager(){
      JpaTransactionManager transactionManager = new JpaTransactionManager();
      transactionManager.setEntityManagerFactory(
       entityManagerFactoryBean().getObject() );

      return transactionManager;
   }

   @Bean
   public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
      return new PersistenceExceptionTranslationPostProcessor();
   }

   Properties additionalProperties() {
      return new Properties() {
         {  // Hibernate Specific: 
            setProperty("hibernate.hbm2ddl.auto", "create-drop");
            setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
         }
      };
   }
}

Also, note that, before Spring 3.2, cglib had to be on the classpath for Java @Configuration classes to work; to better understand the need for cglib as a dependency, see this discussion about the cglib artifact in Spring.

3. The JPA Spring Configuration with XML

The same Spring Configuration with XML:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
   xmlns:tx="http://www.springframework.org/schema/tx"
   xsi:schemaLocation="

http://www.springframework.org/schema/beans


http://www.springframework.org/schema/beans/spring-beans-3.2.xsd


http://www.springframework.org/schema/tx

      http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">

   <bean id="myEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <property name="packagesToScan" value="org.baeldung.persistence.model" />
      <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
      </property>
      <property name="jpaProperties">
         <props>
            <prop key="hibernate.hbm2ddl.auto">create-drop</prop>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
         </props>
      </property>
   </bean>

   <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
      <property name="driverClassName" value="com.mysql.jdbc.Driver" />
      <property name="url" value="jdbc:mysql://localhost:3306/spring_jpa" />
      <property name="username" value="tutorialuser" />
      <property name="password" value="tutorialmy5ql" />
   </bean>

   <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
      <property name="entityManagerFactory" ref="myEmf" />
   </bean>
   <tx:annotation-driven />

   <bean id="persistenceExceptionTranslationPostProcessor" 
      class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

</beans>

There is a relatively small difference between the way Spring is configured in XML and the new Java based configuration – in XML, a reference to another bean can point to either the bean or a bean factory for that bean. In Java however, since the types are different, the compiler doesn’t allow it, and so the EntityManagerFactory is first retrieved from it’s bean factory and then passed to the transaction manager:

txManager.setEntityManagerFactory( this.entityManagerFactoryBean().getObject() );

4. Going full XML-less

Usually JPA defines a persistence unit through the META-INF/persistence.xml file. Starting with Spring 3.1, the persistence.xml is no longer necessary – the LocalContainerEntityManagerFactoryBean now supports a ‘packagesToScan’ property where the packages to scan for @Entity classes can be specified.

This file was the last piece of XML to be removed – now, JPA can be fully set up with no XML.

4.1. The JPA Properties

JPA properties would usually be specified in the persistence.xml file; alternatively, the properties can be specified directly to the entity manager factory bean:

factoryBean.setJpaProperties( this.additionalProperties() );

As a side-note, if Hibernate would be the persistence provider, then this would be the way to specify Hibernate specific properties.

5. The Maven configuration

In addition to Spring Core and persistence dependencies – show in detail in the Spring with Maven tutorial – we also need to define JPA and Hibernate in the project, as well as a MySQL connector:

<dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-entitymanager</artifactId>
   <version>4.2.4.Final</version>
   <scope>runtime</scope>
</dependency>

<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>5.1.26</version>
   <scope>runtime</scope>
</dependency>

Note that the MySQL dependency is included as a reference – a driver is needed to configure the datasource, but any Hibernate supported database will do.

6. Conclusion

This tutorial illustrated how to configure JPA with Hibernate in Spring using both XML and Java configuration.

We also discussed how to get rid of the last piece of XML usually associated with JPA – the persistence.xml. The final result is a lightweight, clean DAO implementation, with almost no compile-time reliance on Spring.

The implementation of this Spring JPA Tutorial can be found in the github project – this is an Eclipse based project, so it should be easy to import and run as it is.
 

Reference: Spring 3 and JPA with Hibernate from our JCG partner Eugen Paraschiv at the baeldung blog.

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you two of our best selling eBooks for FREE!

JPA Mini Book

Learn how to leverage the power of JPA in order to create robust and flexible Java applications. With this Mini Book, you will get introduced to JPA and smoothly transition to more advanced concepts.

JVM Troubleshooting Guide

The Java virtual machine is really the foundation of any Java EE platform. Learn how to master it with this advanced guide!

Given email address is already subscribed, thank you!
Oops. Something went wrong. Please try again later.
Please provide a valid email address.
Thank you, your sign-up request was successful! Please check your e-mail inbox.
Please complete the CAPTCHA.
Please fill in the required fields.

Leave a Reply


× 2 = fourteen



Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use | Privacy Policy
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.
Do you want to know how to develop your skillset and become a ...
Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you two of our best selling eBooks for FREE!

Get ready to Rock!
You can download the complementary eBooks using the links below:
Close