在 @Transactional 方法中获取 LazyInitializationException

Question

当我从控制器访问此方法时遇到此异常：

{"status":"failure","exception":"LazyInitializationException","exceptionMessage":"失败 懒惰地初始化角色集合： org.mainco.subco.lessonplan.domain.LessonPlan.classrooms，不能 初始化代理 - 没有会话","errorMessage":"懒惰地失败 初始化角色集合： org.mainco.subco.lessonplan.domain.LessonPlan.classrooms，不能 初始化代理 - 没有会话”}

控制器：

@Autowired
private ThirdPartyService m_thirdPartySvc;

…

@RequestMapping(value = "/launch", method = RequestMethod.GET)
@Transactional
public String launchLti(final @RequestParam String assignmentId,
                        final Model model,
                        final HttpServletRequest request,
                        final HttpServletResponse response,
                        final Principal principal) throws InvalidKeyException, UnsupportedEncodingException, NoSuchAlgorithmException
{
    final subcoAuthenticationUser auth = (subcoAuthenticationUser) ((Authentication) principal).getPrincipal();
    String nextPage = null;
    final User user = m_userSvc.findById(auth.getId());

    // Provision the assignment in ThirdParty if not already done so
    final Assignment assmt = m_lessonPlanDao.getAssignment(assignmentId);
    if (!assmt.isSentToThirdParty())
    {
        m_thirdPartySvc.sendAssignment(assignmentId);
    }   // if

@Transactional 注释是不必要的吗？特别是因为我已经在我的@Service 课堂上使用了它……

@Service
@Transactional
public class ThirdPartyServiceImpl implements ThirdPartyService
{

    @Override
    public void sendAssignment(final String assignmentId)
    {
        final Assignment assignment = m_lessonPlanDao.getAssignment(assignmentId);
        if (isThirdPartyAssignment(assignment))
        {
            final String ThirdPartyPromptId = assignment.getTocItem().getThirdPartyPromptId();
            // Gather the teacher id
            final LessonPlan lessonPlan = m_lessonPlanDao.getLessonPlan(assignment.getLessonPlan().getId());
            final String teacherId = lessonPlan.getOwnerId();
            // Gather the students who have been assigned this assignment
            final List<Classroom> classes = lessonPlan.getClassrooms();
            // Send one request for each class assignment
            for (final Classroom classroom : classes)
            {

错误发生在for (final Classroom classroom : classes) 行。我到处都有@Transactional，但我得到了这个LazyInitializationException。为什么？以及如何创建事务以便我可以运行我的方法？

我在 JBoss 7.1.3.Final 上使用 Spring 3.2.11.RELEASE、Hibernate 4.3.6.Final 和 JPA 2.1。如果升级其中任何一个可以解决我的问题，请告诉我。

Answer 1

应用程序在运行时遵守@Transactional 边界。您可以拨打以下电话查询：TransactionSynchronizationManager#isActualTransactionActive()

添加一些代码以打印出上述方法的值。如果它是错误的，那么您可能需要确保 component-scan 设置正确。

示例：<context:component-scan base-package="com.application.dao" />

这将完全错过com.application.service 包中的类。