question about using localthread in hibernate?

[Robert Strong]

hi, I've been told to use threadlocal to store a hibernate session used in a stateless session bean, like below:

public class HibernateSessionFactory {

public static final ThreadLocal session = new ThreadLocal();
private static SessionFactory sessionFactory;

public static void init() throws HibernateException {
sessionFactory = new Configuration().configure().buildSessionFactory();
}

public static Session currentSession() throws HibernateException {
Session s = (Session) session.get();

if (s == null) {
s = sessionFactory.openSession();
session.set(s);
}
return s;
}

public static void closeSession() throws HibernateException {
Session s = (Session) session.get();

session.set(null);
if (s != null)
s.close();
}

the thing I don't understand is that hibernate session is stored in ThreadLocal using Singleton, so all the threads can access to the static variable, how could the hibernate session object be stored in the local thread of a stateless session bean respectively?

any help appreciated