Composite Key with Hibernate

In order to generate the next SQL code:

create table users (
    user_name varchar(15) not null primary key, 
    user_pass varchar(15) not null);

create table user_roles(
    username varchar(15) not null,
    role_name varchar(15) not null, 
    primary key(usernmae, rolename)
);

You can use code such as:

 <?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="databaselayer.users.UserDB" table="users">
        <id name="username" type="string" column="user_name">
                <meta attribute="scope-set">public</meta>      
        </id>    
        <property name="password" type="string" column="user_pass"  not-null="true"/>
        <set name="roles" cascade="save-update" inverse="true">
                <key column="user_name"/>
                <one-to-many class="databaselayer.users.RoleDB"/>
        </set>                       
    </class>
   <class name="databaselayer.users.RoleDB" table="user_roles">
        <composite-id>
            <key-many-to-one name="username" class="databaselayer.users.UserDB" column="user_name"/>
            <key-property name="role" type="string" column="role_name"/>
        </composite-id>             
    </class>          
</hibernate-mapping>

You may need to have your classes as well as hbm mapping files in your classpath.
Next I post my Ant schema target:
Note ${basedir}/build/WEB-INF/classes contains both *.class and *.hbm.xml files.

<target name="schema" description="Generate DB schema from the O/R mapping files">
    <hibernatetool destdir="${basedir}">            
        <classpath path="${basedir}/build/WE