How to map org.postgresql.geometric.PGpoint to Hibernate Type

First and foremost, I think GEOMETRY data types are supported by Hibernate Spatial, but if they are not, you can always define a custom Hibernate Type and a custom Hibernate Dialect.

I had a similar problem when managing a POINT column which contained geography points.

I created a PostgisDialect class which extended PostgreSQL9Dialect, where you register the new data type in this way

public PostgisDialect() {
    registerColumnType(Types.BINARY, "geography");        
}

in your case, you would register the type as "geometry"

then, you define a GeometryType class which implements UserType

Oddly enough, the process of writing a custom Hibernate Type is not one of the most documented features, so I will paste here what I wrote to define my PointType. For the other methods in the interface, I let them throw UnsupportedOperationException

public class PointType implements UserType{
private static final Type[] PROPERTY_TYPES = new Type[] { 
    StringType.INSTANCE };
public String[] getPropertyNames() {
     return new String[] {"point"};   }

public Type[] getPropertyTypes() {
    return PROPERTY_TYPES;
}


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

public boolean equals(Object o, Object o1) throws HibernateException {
    if((o instanceof Point && o1 instanceof Point) == false)
        return false;
    Point p1 = (Point) o;
    Point p2 = (Point) o1;
    boolean equal = ((p1.getX() == p2.getX()) && (p1.getY() == p2.getY()));
    return equal;


}   

public Object nullSafeGet(ResultSet rs, String[] strings, SessionImplementor si, Object o) throws HibernateException, SQLException {
// the method which gets the data from the column and converts it to a Point using       BinaryParser
   BinaryParser bp = new BinaryParser();       
   try{          
      String binaryString = rs.getString(strings[0]);
       return bp.parse(binaryString);
   }
   catch(Exception ex){ return null;}

}

public void nullSafeSet(PreparedStatement ps, Object o, int i, SessionImplementor si) throws HibernateException, SQLException {
    Point p = (Point) o ;
    if(p!=null){
       BinaryWriter bw = new BinaryWriter();
       ps.setObject(i,bw.writeBinary(p));      
    }

public Object deepCopy(Object o) throws HibernateException {
    Point p = (Point) o;        
    Point newPoint = null;
    if(p!=null){
        newPoint = new Point(p.x, p.y);
        newPoint.setSrid(p.getSrid());
    }
    return newPoint;

}

public boolean isMutable() {
    return true;
}


public int[] sqlTypes() {
    return new int[]{Types.BINARY};
}    

}

some quick notes: nullSafeSet and nullSafeGet writes and reads the values to/from the database, respectively, using the BinaryWriter/BinaryParser objects.

Once you have defined all this, this is how you annotate your model class so that it uses your custom type

@Column(name="point")
@Type(type="eu.enricorampazzosoluzioni.incidentpredicter.dataCopier.hibernate.types.PointType")
private Point point;

Last, but not least, you need to tell Hibernate to use your custom dialect. If you use Spring to define your session factory, you can define it via hibernateProperties

<property name="hibernateProperties">
     <props>           
         <prop key="hibernate.dialect">eu.enricorampazzosoluzioni.incidentpredicter.dataCopier.hibernate.dialect.PostgisDialect</prop>            
     </props>
  </property>