Hibernate using multiple databases

Question

Someone know how to add a another datasource in hibernate configuration and how to configure Spring to that datasource its autoinject in my respective DAO?

This is m

Answer 1

I had another way to offer which works only with java classes and annotations. Check it out at this SO post. https://stackoverflow.com/a/61232164/5681666

Answer 2

I'll add my example too. Maybe it will be usefull for another situations like getting data from one database and writing it to another with EntityManager.

So my applicationContext.xml:

<context:annotation-config />
<tx:annotation-driven transaction-manager="transactionManager" />

<!-- Connection 1 -->

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
  <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="dataSource" ref="dataSource" />
  <property name="persistenceUnitName" value="unitRemote" />
  <property name="packagesToScan" value="business.domain" />
</bean>

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
  <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
  <property name="url" value="jdbc:oracle:thin:@remote_host:1521:xe" />
  <property name="username" value="USER" />
  <property name="password" value="PASSWORD" />
</bean>


<!-- Connection 2 -->

<bean id="transactionManagerLocal" class="org.springframework.orm.jpa.JpaTransactionManager">
  <property name="entityManagerFactory" ref="entityManagerFactoryLocal" />
</bean>

<bean id="entityManagerFactoryLocal" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="dataSource" ref="dataSourceLocal" />
  <property name="persistenceUnitName" value="unitLocal" />
  <property name="packagesToScan" value="local.business.domain" />
</bean>

<bean id="dataSourceLocal" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
  <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
  <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe" />
  <property name="username" value="USER_LOC" />
  <property name="password" value="PASSWORD_LOC" />
</bean>

Package business.domain has entity classes for remote connection.

Package local.business.domain has entities for local connection.

Entities have annotation mappings for columns and relations.

Then 2 DAO classes:

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

@Repository
public class RemoteDao {

  @PersistenceContext(unitName="unitRemote")
  protected EntityManager em;

  // ...

}

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

@Repository
@Transactional(value="transactionManagerLocal")
public class LocalDao {

  @PersistenceContext(unitName="unitLocal")
  protected EntityManager em;

  // ...

}

With this I could use @Autowired to inject DAOs in my JUnit test:

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "/config/applicationContext.xml" })
public class DaoTest {

  @Autowired
  private RemoteDao remoteDao;

  @Autowired
  private LocalDao localDao;


  @Test
  public void daoTest(){
    Entity entity = remoteDao.find(id);
    localDao.persist(entity);
  }

}

So here it's possible to use DAOs without service if this is needed for simple applications, tests or DB migration scripts.

Answer 3

ok. I find another solution, and that is using the same method like this: add another dataSource and SessionFactory, next in the method of DAO that injject the sessionFactory add the @Qualifier anottation withe the property of the sessionFactory required, like this:

  @Autowired 
    public ProgramaSgteDAOHibernate(@Qualifier("sessionFactory3") SessionFactory sessionFactory) { 
     super(sessionFactory); 
    }