Purpose of using java.lang.reflect.Proxy ?

Hi,

This is a newbie question... I've just read that using a proxy inside
application code is quite unusual, and that it's mostly used in
frameworks... In an app I've inherited, I find the following lines:

DFLT_SESS_FACT = HibernateSupport.getSessionFactory
("hibernate.cfg.xml",
                                   JdbcStuffDAO.class.getClassLoader
(),
                                   new StuffBaseEntityInterceptor());
[...]
public IStuffService2 getStuffService(String p_user,
                                      String p_password,
                                      ApplicationCode
p_applicationCode,
                                      SessionFactory
p_sessionFactory)
throws StuffException
{
  JdbcStuffServiceImpl l_service =
       new JdbcStuffServiceImpl(p_user,p_applicationCode,new
JdbcStuffDAO(p_sessionFactory));
  IStuffService2 l_proxy =
       (IStuffService2)Proxy.newProxyInstance
(JdbcStuffFactory.class.getClassLoader(),
                         new Class[] {IStuffService2.class},
                         new HibernateSessionInvocationHandler
(DFLT_SESS_FACT,l_service,l_service.getLocale()));
  return l_proxy;
}

I'm not familiar with this Proxy thing... What purpose does it serve ?
I've noticed this method could return 'l_service' as well (cause
JdbcStuffServiceImpl implements IStuffService2), and thus have:
{
  JdbcStuffServiceImpl l_service =
       new JdbcStuffServiceImpl(p_user,p_applicationCode,new
JdbcStuffDAO(p_sessionFactory));
  return l_service;
}
but I haven't tested it.
What did the guy who wrote these lines want to achieve ? (he's left,
so
I can't ask him...)

Thanks for your help...
Regards,
S=E9bastien