How do I configure Hibernate with a JPA 2.0 file?

Hibernate docs show very clearly how to configure Hibernate with XML.

This is the snippet of code to do so:

new Configuration().configure("catdb.cfg.xml")

Now how do you configure Hibernate when instead of a hibernate configuration file, you have a JPA 2.0 config file ?

• How to do it for META-INF/persistence.xml ?
• What if my file is called META-INF/jpa.xml instead ?

This is for Hibernate 3.6 and JPA 2.0. My ultimate goal is to be able to export a schema DDL for the classes described in file persistence.xml, so I don't want to build a 开发者_StackOverflow社区SessionFactory.

    Configuration cfg = /* ??? */

    SchemaExport schemaExport = new SchemaExport(cfg);
    schemaExport.setDelimiter(";");
    schemaExport.setOutputFile("ddl.sql");
    boolean script = true, export = false, justDrop = false, justCreate = false;
    schemaExport.execute(script, export, justDrop, justCreate);

Assuming you would ordinarily look up your configuration using a persistence unit name, you can create an org.hibernate.ejb.Ejb3Configuration and get it to return the wrapped org.hibernate.cfg.Configuration:

package test;

import org.hibernate.cfg.Configuration;
import org.hibernate.ejb.Ejb3Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class SchemaExportTest {
    public static void main(String[] args) {
        Configuration cfg = new Ejb3Configuration().configure( "persistence-unit-name", null ).getHibernateConfiguration();

        SchemaExport export = new SchemaExport(cfg);

        export.execute(true, false, false, false);
    }
}

If you use JPA 2.0 with Hibernate, the only file you need is the persistence.xml file located in the META-INF directory.

How to configure the persistence.xml file is an extensive subject and depends on the type of application you are building.

For instance, I am currently running an application with Hibernate 3.6.2 whose only configuration file is the persistence.xml and it only has the following lines

<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_2_0.xsd" version="2.0">
   <persistence-unit name="xyz" transaction-type="RESOURCE_LOCAL"/>
</persistence>

That's all I need. At runtime, when I start the entity manager factory, I provide a few more properties , but what I intent to demonstrate, is how easy it can be to configure JPA with Hibernate.