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我为我的移动客户端制作了一个 REST 服务器。我正在使用休眠进行数据库访问。但我似乎对这段代码有一些问题

    public PlacesAssociation getPlacesAssocitionById(String id) {
    session = HibernateUtil.getSessionFactory().getCurrentSession();
    PlacesAssociation placesAssociation=null;
    try {
        session.beginTransaction();
        placesAssociation = (PlacesAssociation) session.get(
                PlacesAssociation.class, id);
        session.getTransaction().commit();
    } catch (RuntimeException e) {
        session.getTransaction().rollback();
        e.printStackTrace();
    }
    return placesAssociation;
}

我已经通过触发查询在我的数据库中手动看到了我得到结果的位置，但是在这里我有时会得到 NullPointerException。由于这个问题是偶然的，因此追踪它变得非常困难

谁能帮我解决这个问题

这是调用代码

  public Response getSpecificRide(@PathParam("id") String id) {
    // TODO Hibernate for a specific ride identified by the ride id.
    try {
        System.out.println("Get Specific Ride " + id);
        Ride ride = rideRepository.getRideById(Long.parseLong(id));
        RideDetailWrapper rideDetailWrapper = new RideDetailWrapper();
        PlacesAssociation placesAssociationFrom = placesAssociationRepository.getPlacesAssocitionById(ride.getFromId());
        PlacesAssociation placesAssociationTo = placesAssociationRepository.getPlacesAssocitionById(ride.getToId());
        rideDetailWrapper.setId(ride.getId());
        rideDetailWrapper.setInterval(ride.getInterval());
        rideDetailWrapper.setSeatsAvailable(ride.getSeatsAvailable());
        rideDetailWrapper.setTime(ride.getTime());
        rideDetailWrapper.setFromAddress(placesAssociationFrom.getName());
            rideDetailWrapper.setFromVicinity(placesAssociationFrom.getVicinity());
        rideDetailWrapper.setToAddress(placesAssociationTo.getName());
        rideDetailWrapper.setToVicinity(placesAssociationTo.getVicinity());
        rideDetailWrapper.setVehicleType(ride.getVehicleType());
        for (User user : ride.getUsers()) {
            UserDetail userDetail = userRepository.getUserDetailByRegistrationId(user.getRegistrationId());
            UserDetailWrapper userDetailWrapper = new UserDetailWrapper();
            userDetailWrapper.setRegistrationId(userDetail.getRegistrationId());
            userDetailWrapper.setAge(userDetail.getAge());
            userDetailWrapper.setFirstName(userDetail.getFirstName());
            userDetailWrapper.setLastName(userDetail.getLastName());
            userDetailWrapper.setSex(userDetail.getSex());
            List<UserDetailWrapper> userDetailWrappers = rideDetailWrapper.getUserDetailWrappers();
            userDetailWrappers.add(userDetailWrapper);
            rideDetailWrapper.setUserDetailWrappers(userDetailWrappers);
        }
        return Response.ok(rideDetailWrapper).build();
    } catch (Exception e) {
        e.printStackTrace();
        System.out.println("Problem with Get Specific Ride");
        return Response.serverError().build();
    }
}

我在这条线上遇到错误RideDetailWrapper.setFromAddress(placesAssociationFrom.getName());

4

1 回答 1

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if (placesAssociationFrom!=null) {
   rideDetailWrapper.setFromAddress(placesAssociationFrom.getName());
   ...
}

或在需要时抛出异常placesAssociationFrom==null

同样应该是placesAssociationTo

还

if (ride!=null && ride.getUsers()!=null)
for (User user : ride.getUsers()) {
   ...
}
于 2013-05-28T01:33:26.117 回答