Question

我对Hibernate相当新，并且一直在使用手册＆amp;在线论坛，但我对这个问题感到难过。我正在使用Spring 3.2和Hibernate 4＆amp;注释。我有一个父母（PledgeForm）＆amp;子（PledgeFormGiftLevel）表是一对多的。

域/型号：父

@Entity
@Table(name="PLEDGE_FORMS")
@SuppressWarnings("serial")
public class PledgeForm implements Serializable {

static final Logger log = Logger.getLogger(PledgeForm.class);

@Id
@GeneratedValue(strategy=GenerationType.AUTO, generator="pledge_form_seq")
@SequenceGenerator(name="pledge_form_seq", sequenceName="PLEDGE_FORM_SEQ")
@Column(name="ID", unique=true, nullable=false)
private Integer id;

….

@OneToMany(mappedBy="pledgeForm", fetch=FetchType.EAGER, cascade=CascadeType.ALL)//********1
private List<PledgeFormGiftLevel> pledgeFormGiftLevels = new ArrayList<PledgeFormGiftLevel>();

….

public List<PledgeFormGiftLevel> getPledgeFormGiftLevels() {
   return this.pledgeFormGiftLevels;
}

public void setPledgeFormGiftLevels(List<PledgeFormGiftLevel> pledgeFormGiftLevels) {
   this.pledgeFormGiftLevels = pledgeFormGiftLevels;
}

//I do not think the following method is needed, but I decided to try it just in case
public void addPledgeFormGiftLevels(PledgeFormGiftLevel pledgeFormGiftLevels) {
   pledgeFormGiftLevels.setPledgeForm(this);
   getPledgeFormGiftLevels().add(pledgeFormGiftLevels);
}

儿童

@Entity
@Table(name="PLEDGE_FORM_GIFT_LEVELS")
@SequenceGenerator(name="pledge_form_gift_level_seq", sequenceName="PLEDGE_FORM_GIFT_LEVEL_SEQ")
@SuppressWarnings("serial")
public class PledgeFormGiftLevel implements Serializable {

static final Logger log = Logger.getLogger(PledgeFormGiftLevel.class);

@Id
@GeneratedValue(strategy=GenerationType.AUTO, generator="pledge_form_gift_level_seq")
@Column(name="ID", unique=true, nullable=false)
private Integer id; 

…

@ManyToOne(fetch=FetchType.EAGER)//yes?
@JoinColumn(name="PLEDGE_FORM_ID", referencedColumnName="ID", insertable=true, updatable=true)//yes?
private PledgeForm pledgeForm = new PledgeForm();

…

public PledgeForm getPledgeForm() {
   return pledgeForm;
}
public void setPledgeForm(PledgeForm pledgeForm) {
   this.pledgeForm = pledgeForm;
}

控制器（有一个图形，所以我有代码来拉入文件）：

@Controller
@SessionAttributes("pledgeForm")
public class PledgeFormController {
   @Autowired
   org.unctv.service.PledgeFormManager Service;

…

@RequestMapping(value = "/saveJdbcPledgeForm", method = RequestMethod.POST, params="save")
public ModelAndView save(
   @ModelAttribute("pledgeForm")
   @Valid PledgeForm pledgeForm, BindingResult result,
   @RequestParam("logoImg") MultipartFile file,
   @RequestParam(value="removeLogoImg", required=false) String removeLogoImg) throws Exception {

      ModelAndView mav = null;
      mav = new ModelAndView("pledgeFormSearch");//Name of the JSP

      if (removeLogoImg != null) {
         pledgeForm.setLogoFilename(null);

         pledgeForm.setLogoImg(null);
         pledgeForm.setLogoContentType(null);
      } else if (file != null && file.getBytes().length > 0) {
         pledgeForm.setLogoFilename(file.getOriginalFilename());
         pledgeForm.setLogoImg(file.getBytes());
         pledgeForm.setLogoContentType(file.getContentType());
      }

      Service.save(pledgeForm);
      mav.addObject("pledgeForm", pledgeForm);//JSP Form's Command Name (pledgeForm); 
      mav.addObject("cmdName", "pledgeForm");
      mav.addObject("actionType", "Save");
      return mav;
}

服务

@Service("simplePledgeFormManager")
@Transactional(readOnly=true)
public class SimplePledgeFormManager implements PledgeFormManager { 
   @Autowired
   private HibernatePledgeFormDao hibernatePledgeFormDao;


…

@Transactional(readOnly=false)
public void save(PledgeForm pledgeForm) throws Exception {
   hibernatePledgeFormDao.save(pledgeForm);
}

DAO：

@Repository("PledgeFormDAO")
public class HibernatePledgeFormDao implements PledgeFormDao {

static final Logger log = Logger.getLogger(HibernatePledgeFormDao.class);

   @Autowired
   private SessionFactory sessionFactory;


...

@Override
public void save(PledgeForm pledgeForm) throws Exception {
   sessionFactory.getCurrentSession().saveOrUpdate(pledgeForm);
}

使用上面的代码，可以选择并更新父/子记录。当我显示来自休眠的“跟踪”消息时，更新确实有关于孩子的跟踪消息：

[2013-12-06 10:31:24,648] TRACE Persistent instance of: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:31:24,649] TRACE Ignoring persistent instance
[2013-12-06 10:31:24,649] TRACE Object already associated with session: [org.unctv.domainmodel.PledgeFormGiftLevel#1]

如果有子记录，则create始终会出现此错误：

object references an unsaved transient instance - save the transient instance before flushing: org.unctv.domainmodel.PledgeForm; nested exception is org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: org.unctv.domainmodel.PledgeForm

当我查看hibernate日志时，我发现它更新了父级＆amp;孩子基于瞬态物体。然后它试图冲洗＆amp;找到孩子的持久副本，所以它会回滚所有内容。

[2013-12-06 10:34:13,615] TRACE Automatically flushing session
[2013-12-06 10:34:13,615] TRACE Flushing session
[2013-12-06 10:34:13,615] DEBUG Processing flush-time cascades
[2013-12-06 10:34:13,615] TRACE Processing cascade ACTION_SAVE_UPDATE for: org.unctv.domainmodel.PledgeForm
[2013-12-06 10:34:13,615] TRACE Cascade ACTION_SAVE_UPDATE for collection: org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels
[2013-12-06 10:34:13,615] TRACE Cascading to save or update: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:34:13,616] TRACE Persistent instance of: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:34:13,616] TRACE Ignoring persistent instance
[2013-12-06 10:34:13,616] TRACE Object already associated with session: [org.unctv.domainmodel.PledgeFormGiftLevel#51]
[2013-12-06 10:34:13,616] TRACE Done cascade ACTION_SAVE_UPDATE for collection: org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels
[2013-12-06 10:34:13,616] TRACE Done processing cascade ACTION_SAVE_UPDATE for: org.unctv.domainmodel.PledgeForm
[2013-12-06 10:34:13,617] DEBUG Dirty checking collections
[2013-12-06 10:34:13,617] TRACE Flushing entities and processing referenced collections
[2013-12-06 10:34:13,617] DEBUG Collection found: [org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels#51], was: [<unreferenced>] (initialized)
[2013-12-06 10:34:13,618] DEBUG rolling back
[2013-12-06 10:34:13,618] DEBUG rolled JDBC Connection

Hibernate文档显示这比我的代码更简单，但我不得不添加fetch＆amp;级联值。我玩过改变fetch＆amp;级联值和放置（从Hibernate文档开始，然后添加），但我尝试的其他所有内容仍导致创建失败＆amp;经常导致更新失败。

我发现很多论坛帖子都显示了flush（）或evict（）。我不确定它是Hibernate 4还是注释（@Transactional，我认为）我正在使用，但我在代码中看不到它的位置。从Hibernate跟踪日志中，我可以看到在saveOrUpdate（）方法中自动进行刷新。

我也试过放下桌子和放大器。序列＆amp;开始新鲜。

任何关于让创作工作的建议都值得赞赏。如果你能指出我错过的具体文件，那也是值得赞赏的。

谢谢，邦尼

Answer 1

我注意到equals和hashcode未在实体中被覆盖。这些方法用于比较对象以确定它们的相等性。如果不覆盖这些方法，Hibernate可能无法确定实体的现有实例是否存在。尝试为hashcode和equals提供实施。

如果您使用Eclipse，请按CTRL + SHIFT + S，H以显示创建hashcode和{{1}的对话框} 方法。选择包含相对不变的值的字段，然后生成方法。

还要确保您正在管理实体的两面，如上述评论所述：

equals

OneToMany创建失败，出现InvalidDataAccessApiUsageException

1 个答案: