我正在尝试创建一个简单的网页,用于显示从网络服务接收的数据
@Service
@Transactional
public class TopicService {
@Autowired
private TopicRepository topicRepository;
public int saveTopic(Topic topic){
return topicRepository.save(topic).getId();
}
public Iterable<Topic> findAllTopics(){
return topicRepository.findAll();
}
public Topic findTopicByID(Long id){
return topicRepository.findOne(id);
}
public List<Topic> findTopicsByTag(Tag tag){
return topicRepository.findAllByTopicTag(tag);
}
}
主题存储库扩展了 CRUD 存储库
@Repository
public interface TopicRepository extends CrudRepository<Topic, Long>
{
List<Topic> findAllByTopicTag(Tag currentTag);
}
Controller 通过以下方式调用服务
@Controller
public class HomeController {
private TopicService service;
private static final Logger logger = LoggerFactory.getLogger(HomeController.class);
@RequestMapping(value = "/", method = RequestMethod.GET)
public ModelAndView home(Locale locale, Model model)
{
Iterable<Topic> listTopic = service.findAllTopics();
return new ModelAndView("home", "model", listTopic);
}
}
这个字符串
Iterable listTopic = service.findAllTopics();
抛出空指针异常。我猜是因为该服务尚未初始化。我怎样才能正确执行服务初始化?
最佳答案
您需要在 HomeController
中 Autowiring TopicService
:
@Controller
public class HomeController {
@Aurowired
private TopicService service;
关于java - 如何初始化网络服务,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9033065/