I'm setting up a Project with Spring and Hibernate. I created an abstract DAO class that contains an EntityManager. When I want to use this EntityManager, it's null and I dont understand why. Maybe you can help me.
My persistence-context
<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"
xmlns:p="http://www.springframework.org/schema/p" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">
<import resource="persistence-beans.xml" />
<mvc:annotation-driven />
<bean id="jdbcPropertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
p:location="classpath:META-INF/mysql.properties" />
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource"
p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.url}"
p:username="${jdbc.username}" p:password="${jdbc.password}" />
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="persistenceUnit" />
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="${hibernate.show_sql}" />
<property name="generateDdl" value="${hibernate.generate_ddl}" />
<property name="databasePlatform" value="${hibernate.dialect}" />
</bean>
</property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean id="personDao" class="com.patrickzinner.dao.PersonDao" />
<tx:annotation-driven transaction-manager="transactionManager" />
PersonDao.java:
@Repository
@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public class PersonDao extends AbstractDao<Person> {
public PersonDao() {
super(Person.class);
}
}
AbstractDao.java
@SuppressWarnings("unchecked")
@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public abstract class AbstractDao<T> {
@PersistenceContext
protected EntityManager em;
private Class<T> entityClass;
public AbstractDao(Class<T> entityClass) {
this.entityClass = entityClass;
}
public AbstractDao() {
}
public void create(T entity) {
this.em.persist(entity);
}
public void edit(T entity) {
this.em.merge(entity);
}
public void remove(T entity) {
this.em.remove(this.em.merge(entity));
}
public T find(long primaryKey) {
return this.em.find(entityClass, primaryKey);
}
@SuppressWarnings("rawtypes")
public List<T> findAll() {
CriteriaQuery cq = this.em.getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));
return this.em.createQuery(cq).getResultList();
}
}
Thanks in advance!
An entity manager can only be injected in transaction classes. In other words, it can only be injected in a EJB. Other classe must use an EntityManagerFactory to create and destroy an EntityManager.
but your AbstractDAO is not EJB you can not use EntityManager directly.
solution
@PersistenceUnit(unitName = "test")
private EntityManagerFactory entityManagerFactory;
EntityManager entityManager = entityManagerFactory.createEntityManager();
then perform operation using emtityManager.
alternatively you can use container managed Transaction using JNDI lookup..
let me know for any issues.
Try adding <context:annotation-config />
to your persistence-context. This section of the reference manual may help you to use @PersistenceContext
.
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