Database access from Oracle Java Cloud Service application

Question

I have registered for Oracle Java Cloud Service for trial period. I want to deploy a Spring MVC 3.2 and Hibernate 4.0 web application.
I created a table in the Database Cloud. I am not sure how do I access the Database Cloud Service from my application.
Need your guidance/pointers/references that can help me establish connection from my application to the database.
Thanks,
Ujjwal

Answer 1

Hi,
Use JPA - see the visitors example, it uses @PersistenceUnit injection with previously weaved .class entity files.
You can use application managed EMF's and EntityManagers with code like the following - which is not preferable to using @PersistenceContext injection on an @Stateless session EJB but...
          EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAServletPU");
          EntityManager em = emf.createEntityManager();
          EntityTransaction transaction = null;
          try {
               transaction = em.getTransaction();
               transaction.begin();
               Visitor entity = new Visitor();
               entity.setName(name);
               entity.setNum(num);
               em.persist(entity);
               transaction.commit();
               System.out.println("Committing: " + entity);
          } catch (Exception e) {
               e.printStackTrace();
          } finally {
               em.close();
               emf.close();
Use a persistence.xml like the following
<persistence version="2.0" 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_2_0.xsd">
<persistence-unit name="JPAServletPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
     <!--https://cloud.oracle.com/mycloud/f?p=5300:1000:259334829915901-->
<jta-data-source>database</jta-data-source>
<class>com.vision.cloud.jpa.Visitor</class>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
     <property name="eclipselink.target-database" value="Oracle10g" />
<property name="eclipselink.ddl-generation" value="create-tables"/>
<!-- property name="eclipselink.ddl-generation" value="drop-and-create-tables"/-->
</properties>
</persistence-unit>
</persistence>
Check out a tutorial on WebLogic JPA ORM usage here to get started as well.
http://wiki.eclipse.org/EclipseLink/Examples/JPA/WebLogic_Web_Tutorial