UserFacade.java 文件源码

public User findUser(String p_username) {
    CriteriaBuilder builder = em().getCriteriaBuilder();
    CriteriaQuery<User> criteria = builder.createQuery(User.class );
    Root<User> user_root = criteria.from(User.class);
    criteria.select(user_root);
    criteria.where(builder.equal(user_root.get("userName"), p_username));
    try {
        User u =  em().createQuery(criteria).getSingleResult();
        return u;
    } catch (NoResultException ex) {            
        return null;
    }       
}