相关疑难解决方法(0)

你应该把它@Transactional放在DAO类和/或它们的方法中,还是更好地注释使用DAO对象调用的Service类？或者注释两个"层​​"是否有意义？

我有这个问题:

org.hibernate.LazyInitializationException:懒得初始化角色集合:mvc3.model.Topic.comments,没有会话或会话被关闭

这是模型:

@Entity
@Table(name = "T_TOPIC")
public class Topic {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    @ManyToOne
    @JoinColumn(name="USER_ID")
    private User author;

    @Enumerated(EnumType.STRING)    
    private Tag topicTag;

    private String name;
    private String text;

    @OneToMany(mappedBy = "topic", cascade = CascadeType.ALL)
    private Collection<Comment> comments = new LinkedHashSet<Comment>();

    ...

    public Collection<Comment> getComments() {
           return comments;
    }

}

调用模型的控制器如下所示:

@Controller
@RequestMapping(value = "/topic")
public class TopicController {

    @Autowired
    private TopicService service;

    private static final Logger logger = LoggerFactory.getLogger(TopicController.class);


    @RequestMapping(value = "/details/{topicId}", method = RequestMethod.GET)
    public ModelAndView …

考虑我有一个控制器方法get(),它调用一些使用数据库的服务方法.

使整个控制器方法成为事务性或只是每个服务方法是否正确？

在我看来,我们必须进行get()交易,因为它执行相关的操作.

我在Tomcat 7中运行的Web应用程序中使用Spring 3.2和JPA以及Hibernate 4.应用程序分为控制器,服务DAO类.服务类在类和方法级别具有带注释的事务配置.DAO是普通的JPA,实体管理器由@PersistenceContext注释注入.

@Service("galleryService")
@Transactional(propagation=Propagation.SUPPORTS, readOnly=true)
public class GalleryServiceImpl implements GalleryService {

  @Override
  public Picture getPicture(Long pictureId) {
    return pictureDao.find(pictureId);
  }

  @Override
  public List<PictureComment> getComments(Picture picture) {
    List<PictureComment> comments = commentDao.findVisibleByPicture(picture);
    Collections.sort(comments, new Comment.ByCreatedOnComparator(Comment.ByCreatedOnComparator.SORT_DESCENDING));
    return comments;
  }
  ...
}

@Controller
@RequestMapping("/gallery/displayPicture.html")
public class DisplayPictureController extends AbstractGalleryController {

  @RequestMapping(method = RequestMethod.GET)
  public String doGet(ModelMap model, @RequestParam(REQUEST_PARAM_PICTURE_ID) Long pictureId) {
    Picture picture = galleryService.getPicture(pictureId);
    if (picture != null) {
      model.addAttribute("picture", picture);
      // Add comments
      model.addAttribute("comments", galleryService.getComments(picture));
    } else {
      LOGGER.warn(MessageFormat.format("Picture {0} …

我注意到以下内容不适用于标记为@Controller:

@Autowired
SessionFactory sessionFactory;

@ResponseBody
@Transactional
@RequestMapping(method = RequestMethod.GET , value = "/map")

public ArrayList<PhotoDTO> getPhotos(...someParams) {
   Entity result sessionFactory.getCurrentSession()... //do some manipulation

  return result;
}

当我调用URL时,我得到一个错误,说该方法不是事务性的(尽管如您所见,它被标记为一个)

如果我将此方法复制到另一个名为MyService的类并从控制器调用它,它就可以完美地工作

这是一种Spring建议(一个让我多或少使用更多课程的阴谋)？