hibernte criteria只查询表的的某个字段

hibernte criteria只查询表的的某个字段:

 Criteria   criteria=session.createCriteria(User.class); 
  ProjectionList   proList   =   Projections.projectionList();//设置投影集合 
   proList.add(Projections.groupProperty( "userName ")); 
   proList.add(Projections.groupProperty( "password ")); 
   criteria.setProjection(proList); 
    
   最后返回的List是   Object[]   ,   [0]   =   userName,   [1]   =   password