How to use hbm2cfgxml to generate Hibernate JPA configuration file

Hibernate Tools are used as the basis for both Ant tasks and Eclipse plugins, both available from tools.hibernate.org. In this post, you can see a complete Ant script that uses the <hbm2cfgxml> (Hibernate Configuration File) exporter to generate a hibernate.cfg.xml in JPA style. As a prerequisite, we have a META-INF/persistence.xml file in a folder named properties:

<?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="unitTest">    
    <properties>    
      <property name="hibernate.connection.driver_class" 
                                                  value="com.mysql.jdbc.Driver"/>
      <property name="hibernate.connection.url" 
                                    value="jdbc:mysql://localhost:3306/usersdb"/>
      <property name="hibernate.connection.username" value="root"/>
      <property name="hibernate.connection.password" value="root"/>
      <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
    </properties>
  </persistence-unit>
 </persistence>

Based on this file, we have created the below Ant script that generates the hibernate.cfg.xml configuration file (the file is generated into a folder, named hbm2cfgjpa_gen):

<project name="Hibernate Tools for Ant - hbm2cfg_jpa" default="generate">

<!-- Hibernate Tools libraries -->
<property name="librariesdir" value="./libs"/>

<!-- Hibernate Tools libraries paths -->
<path id="libraries">
  <fileset dir="${librariesdir}">
   <include name="*.jar"/>
  </fileset>
</path>

<!-- Directory where the generated .cfg.xml file is saved -->
<property name="build.dir.hbm2cfg_jpa" value="./hbm2cfgjpa_gen"/>

<!-- Define the "hibernatetool" task -->   
<taskdef name="hibernatetool" classname="org.hibernate.tool.ant.HibernateToolTask" 
                                                    classpathref="libraries" />

<!-- Clean the exiting CFG files -->
<target name="clean">
 <delete includeemptydirs="true">
  <fileset dir="${build.dir.hbm2cfg_jpa}" includes="**/*"/>
 </delete>
</target>

<!-- Generating hibernate configuration file via hbm2cfgxml from a basic
    persistence.xml -->
<target name="generate" depends="clean">
<hibernatetool destdir="${build.dir.hbm2cfg_jpa}">
<classpath>
  <path location="./persistence"/>
 </classpath>
 <jpaconfiguration persistenceunit="unitTest"/>
 <hbm2cfgxml ejb3="${ejb3}" />
</hibernatetool>
</target>
</project>

The Ant script is named hbm2cfg_jpa.xml. It runs from command line prompt by:
${your_location}>ant –f hbm2cfg_jpa.xml

A possible output is listed below:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.bytecode.use_reflection_optimizer">false</property>
        <property name="hibernate.connection.autocommit">true</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver
        </property>
        <property name="hibernate.connection.password">root</property>
        <property name="hibernate.connection.release_mode">auto
        </property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/usersdb
        </property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect
        </property>
        <property name="hibernate.ejb.discard_pc_on_close">false</property>
        <property name="hibernate.query.jpaql_strict_compliance">true</property>
        <property name="hibernate.transaction.factory_class">
                       org.hibernate.transaction.JDBCTransactionFactory</property>
        <property name="hibernate.transaction.flush_before_completion">false
        </property>
        <property name="hibernate.use_identifier_rollback">false</property>
    </session-factory>
</hibernate-configuration>

This post is just one of a set of Ant scripts that explores Hibernate Tools for Ant. The complete set can be downloaded from here ( http://www.filefactory.com/file/ca0a5c0/n/HibernateTools.rar ).

From http://e-blog-java.blogspot.com/2011/03/how-to-use-hbm2cfgxml-to-generate_22.html