JPA hibernate 异常 id变更报错。identifier was altered

org.springframework.orm.jpa.JpaSystemException: identifier of an instance of com.thinkgem.jeesite.modules.sys.entity.Office was altered from 151 to 404; nested exception is org.hibernate.HibernateException: identifier of an instance of com.thinkgem.jeesite.modules.sys.entity.Office was altered from 151 to 404 由于缓存了变更之前的id，因此在做修改操作时，清空下balaTruckDao.clear(); @Transactional(readOnly = false) public void save(BalaTruck balaTruck) { //office.id变更导致hibernate持久化异常。因为一级缓存保存了修改之前的office.id。用clear清除session balaTruckDao.clear(); //保存时，前端传入机构id，使用officeDao带出机构code，再持久化保存 balaTruck.setTruckOwnCode(officeDao.findOne(balaTruck.getTruckOwnCode().getId())); balaTruckDao.save(balaTruck); }