Foo看起来里面有这个：

@ManyToMany
private Set<User> favouritedBy;

当用户拥有此功能时：

@ManyToMany(mappedBy = "favouritedBy")
private Set<Foo> favourites  = new HashSet<Foo>();
public Set<Foo> getFavourites() {
  return favourite;
}

fooService拥有此功能，可以通过tranactional方法在打开会话时访问lazyloaded集合：

@Transactional(readOnly = true)
public Set<Foo> getFavourites(User user) {
user = dao.get(User.class, user.getId()); //the dao gets a session
Set<Foo> favourites = user.getFavourites();//but the session is not here and the exception is thrown?
return  favourties;
}

编辑 无需使用标准即可解决此问题：

Set<Foo> favourites = new HashSet<Foo>(user.getFavourites());

这用标准解决了

Session session = sessionFactory.getCurrentSession();
final Criteria crit = session.createCriteria(Foo.class);
crit.setFetchMode("favourites", FetchMode.JOIN);
crit.add(Property.forName("id").eq(id));
return (Foo) crit.uniqueResult();