<?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 package="org.musicbrainz.hibernate">

  <class name="HibernateArtist" table="artist" lazy="true">
    <comment>MusicBrainz Artist.</comment>
   
    <id name="row" column="id">
      <generator class="sequence">
   <param name="sequence">artist_id_seq</param>
      </generator>
    </id>

    <property name="id" type="org.musicbrainz.hibernate.UserUUID" column="gid"/>

    <property name="name" type="string" column="name" not-null="true"/>
    <property name="sortName" type="string" column="sortname" not-null="true"/>
    <property name="disambiguation" type="string" column="resolution"/>
  </class>
 
</hibernate-mapping>

package org.musicbrainz.hibernate;

import org.hibernate.*;
import org.hibernate.usertype.UserType;

import java.io.Serializable;
import java.sql.*;
import java.util.UUID;

public class UserUUID implements UserType {

   private static final int[] SQL_TYPES = { Types.CHAR };

   public int[] sqlTypes() {
      return SQL_TYPES;
   }

   public Class returnedClass() {
      return UUID.class;
   }

   public boolean equals(Object x, Object y)
   throws HibernateException {
      if (x == y) {
         return true;
      } else if (x == null || y == null) {
         return false;
      } else {
         return ((UUID)x).equals((UUID)y);
      }
   }

   public int hashCode(Object x)
   throws HibernateException {
      return ((UUID)x).hashCode();
   }

   public Object nullSafeGet(ResultSet resultSet,
         String[] names, Object owner)
   throws HibernateException, SQLException {
      String uuidString = resultSet.getString(names[0]);
      if (uuidString == null)
         return null;
      return UUID.fromString(uuidString);
   }

   public void nullSafeSet(PreparedStatement statement,
         Object value, int index)
   throws HibernateException, SQLException {
      if (value == null) {
         statement.setNull(index, Types.CHAR);
      } else {
         statement.setString(index, ((UUID)value).toString());
      }
   }

   public Object deepCopy(Object value) throws HibernateException {
      UUID old = (UUID)value;
      return new UUID(old.getMostSignificantBits(), old.getLeastSignificantBits());
   }

   public boolean isMutable() {
      return false;
   }

   public Serializable disassemble(Object value)
   throws HibernateException {
      return (UUID)value;
   }

   public Object assemble(Serializable cached,
         Object owner)
   throws HibernateException {
      return (UUID)cached;
   }

   public Object replace(Object original,
         Object target,
         Object owner)
   throws HibernateException {
      return original;
   }
}

      Iterator artists = session.createQuery("from HibernateArtist").iterate();
      while (artists.hasNext()) {
         Artist a = (Artist)artists.next();
         System.out.println(a.getId());
         System.out.println(a.getName());
      }

Hibernate: select hibernatea0_.gid as col_0_0_ from artist hibernatea0_
2008-10-17 19:46:31,974 WARN [org.hibernate.util.JDBCExceptionReporter] - SQL Error: 0, SQLState: 22003
2008-10-17 19:46:32,034 ERROR [org.hibernate.util.JDBCExceptionReporter] - Bad value for type int : a18fd46d-0fd0-4551-bab0-8c610d3e9c33
Exception in thread "main" org.hibernate.exception.DataException: could not get next iterator result
   at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:100)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
   at org.hibernate.impl.IteratorImpl.next(IteratorImpl.java:156)
   at org.musicbrainz.test.HibernateTest.main(HibernateTest.java:16)
Caused by: org.postgresql.util.PSQLException: Bad value for type int : a18fd46d-0fd0-4551-bab0-8c610d3e9c33
   at org.postgresql.jdbc2.AbstractJdbc2ResultSet.toInt(AbstractJdbc2ResultSet.java:2699)
   at org.postgresql.jdbc2.AbstractJdbc2ResultSet.getInt(AbstractJdbc2ResultSet.java:2016)
   at org.postgresql.jdbc2.AbstractJdbc2ResultSet.getInt(AbstractJdbc2ResultSet.java:2366)
   at org.hibernate.type.IntegerType.get(IntegerType.java:51)
   at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:184)
   at org.hibernate.type.NullableType.nullSafeGet(NullableType.java:173)
   at org.hibernate.type.ManyToOneType.hydrate(ManyToOneType.java:126)
   at org.hibernate.type.EntityType.nullSafeGet(EntityType.java:227)
   at org.hibernate.impl.IteratorImpl.next(IteratorImpl.java:135)
   ... 1 more

<property name="id" type="org.musicbrainz.hibernate.UserUUID" column="gid"/>

<property name="xid" type="org.musicbrainz.hibernate.UserUUID" column="gid"/>