<project name="hbm2java" default="create" basedir=".">

       <description>Cria codigo Java a partir de arquivos .hbm.xml</description>

     <!-- set global properties for this build -->
   <property name="out" value="${basedir}/out"/>
   <property name="xxx.path" value="c:/xxx/xxx/src/"/>

   <path id="class.path">
      <fileset dir="C:/eclipse/plugins/org.hibernate.eclipse_3.0.0.alpha4/lib/">
         <include name="*.jar" />
         <include name="commons-collections-2.1.1.jar" />
      </fileset>
      <pathelement location="c:/xxx/xxx/src/"/>
      <pathelement location="c:/xxx/out/"/>
   </path>


   <taskdef name="hibernatetool" classname="org.hibernate.tool.ant.HibernateToolTask"
            classpathref="class.path"/>

     <target name="clean" description="clean up" >
      <delete dir="${out}"/>
      <mkdir dir="${out}"/>
   </target>

   <target name="create" depends="clean">
      <hibernatetool destdir="${out}" classpath="C:/eclipse/plugins/org.hibernate.eclipse_3.0.0.alpha4/lib/commons-collections-2.1.1.jar;${xxx.path}">
         <configuration configurationfile="c:/xxxx/mappings.cfg.xml" />
         <hbm2java />
      </hibernatetool>
   </target>
</project>

C:\Bancos\hibernate_ant>ant -f exemplo.xml
Buildfile: exemplo.xml

clean:
   [delete] Deleting directory C:\Bancos\hibernate_ant\out
    [mkdir] Created dir: C:\Bancos\hibernate_ant\out

create:
[hibernatetool] Executing Hibernate Tool with a Standard Configuration
[hibernatetool] 1. task: hbm2java (Generates a set of .java files)
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Environment <clinit>
[hibernatetool] INFO: Hibernate 3.0.5
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Environment <clinit>
[hibernatetool] INFO: hibernate.properties not found
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Environment <clinit>
[hibernatetool] INFO: using CGLIB reflection optimizer
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Environment <clinit>
[hibernatetool] INFO: using JDK 1.4 java.sql.Timestamp handling
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Configuration configure
[hibernatetool] INFO: configuring from file: mapeamentos.cfg.xml
[hibernatetool] 15/06/2005 17:29:09 org.hibernate.cfg.Configuration addResource
[hibernatetool] INFO: Mapping resource: xxx/hibernate/map/GraphicElement.hbm.
xml

BUILD FAILED
java.lang.NoClassDefFoundError: org/apache/commons/collections/SequencedHashMap

Total time: 3 seconds