JPA's context injection with Hibernate as engine

[Dan King]

I'm trying to use JPA's Context Injection with Hibernate as the engine. Currently, the context fails to be injected (into entityManager - see code below), I get a NullPointerException error:

Exception in thread "main" java.lang.NullPointerException
at learn.spring.dao.ListingDao.findById(UtilistDao.java:19)

Below is my -- spring configuration, DAO class, & persistence.xml -- anyone see what is wrong/missing? Thanks.

Spring configuration file:

<beans ....>
    
    <tx:annotation-driven />
    <context:annotation-config />
    <aop:aspectj-autoproxy />
    
    <bean id="listingDao" class="learn.spring.dao.ListingDao" />
    
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    	<property name="driverClassName" value="com.mysql.jdbc.Driver" />
    	<property name="url" value="jdbc:mysql://xxx.xxx.xxx.xxx/xxxxx" />
    	<property name="username" value="xxxxxx" />
    	<property name="password" value="xxxxxx" />
    </bean>
    
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    	<property name="persistenceUnitName" value="learnSpring" />
    	<property name="dataSource" ref="dataSource" />
    	<property name="jpaVendorAdapter">
    		<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
    			<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
    			<property name="showSql" value="true" />
    			<property name="generateDdl" value="true" />
    		</bean>
    	</property>
    </bean>
    
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    	<property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>
    ...
    </beans>

DAO class:

    package learn.spring.dao;
    
    import javax.persistence.EntityManager;
    import javax.persistence.PersistenceContext;
    import javax.persistence.Query;
    
    import org.springframework.transaction.annotation.Transactional;
    
    import learn.spring.model.Registration;
    
    @Transactional
    public class ListingDao {
    	public ListingDao() {}
    	
    	@PersistenceContext
    	private EntityManager entityManager;
    	
    	public Registration findById(int id) {
    		Query query = entityManager.createQuery("FROM Registration r WHERE r.memberId = ?1");
    		query.setParameter(1, id);
    		return (Registration) query.getSingleResult();
    	}
    }

persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
    version="1.0">
    
    <persistence-unit name="learnSpring" />
    
    </persistence>

[Mark Spritzler]

Yes, in Spring you want to inject the EntityManagerFactory and not the EntityManager. There might be a way to take your EntityManagerFactory and bind it into JNDI where the EntityManager injection takes place outside of Spring, but I have never tried it myself.

Mark

[Dan King]

Mark Spritzler wrote:Yes, in Spring you want to inject the EntityManagerFactory and not the EntityManager. There might be a way to take your EntityManagerFactory and bind it into JNDI where the EntityManager injection takes place outside of Spring, but I have never tried it myself.

Mark

Mark,

I thought that with Spring 2.5 one could simply use @PersistenceContext (as an alternative to Spring's JpaTemplate) annotation on a property to have it injected with the entity manager; thus allowing one to use entity manager directly rather than the factory.

-Dan

[Mark Spritzler]

Dan King wrote:

Mark Spritzler wrote:Yes, in Spring you want to inject the EntityManagerFactory and not the EntityManager. There might be a way to take your EntityManagerFactory and bind it into JNDI where the EntityManager injection takes place outside of Spring, but I have never tried it myself.

Mark

Mark,

I thought that with Spring 2.5 one could simply use @PersistenceContext (as an alternative to Spring's JpaTemplate) annotation on a property to have it injected with the entity manager; thus allowing one to use entity manager directly rather than the factory.

-Dan

It might be possible with JPA. With Hibernate I always just inject the SessionFactory then in each method call getCurrentSession() on the sessionFactory, because you can't inject a Session and you wouldn't want to since the Repository is a Singleton and created at startup. Then the Session would hold a connection for as long as the App was running. Not good for pooling.

So I assume JPA is the same in Spring. The Repository is a Singleton and you wouldn't want it to hold onto an EntityManager and Connection for the entire time of the App.

Mark