getsingleresult 为空报错 javax.persistence.NoResultException: No entity found for query

getresultlist允许为空

修改如下
public Knowledge getKnowledge(String knowkey) {
String hql = "from Knowledge k where k.knowkey = :knowkey";
Query query = CreateSession().createQuery(hql, Knowledge.class);
query.setParameter("knowkey", knowkey);
if (query.getResultList().size() == 0) {
return null;
} else {
return (Knowledge) query.getSingleResult();
}
}