Question

当我想用@PostConstruct调用方法时，不会调用该方法。我没有从服务器收到任何错误或日志。我是否必须添加一些配置xml文件或添加其他注释才能调用该方法？

的Serlvet：

public class PersonServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;
    private static final Logger LOG = LoggerFactory.getLogger(PersonServlet.class);

    @EJB
    Storage storage;

    protected void service(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException {
      try {
        HttpSession session = req.getSession(true);
        storage = (Storage) session.getAttribute(Storage.class.getName());
        if (storage == null) {
           storage = new Storage();
           session.setAttribute(Storage.class.getName(), storage);
        }     
        // create odata handler and configure it with CsdlEdmProvider and Processor
        OData odata = OData.newInstance();
        ServiceMetadata edm = odata.createServiceMetadata(new PersonEdmProvider(), new ArrayList<EdmxReference>());
        ODataHttpHandler handler = odata.createHandler(edm);
        handler.register(new PersonEntityCollectionProcessor(storage));
        handler.register(new PersonEntityProcessor(storage));
        handler.register(new PersonPrimitiveProcessor(storage));

        // let the handler do the work
        handler.process(req, resp);
      } catch (RuntimeException e) {
        LOG.error("Server Error occurred in ExampleServlet", e);
        throw new ServletException(e);
      }
    }
}

的PersonDAO

@Stateless
public class PersonDAO {

    @PersistenceContext
    private EntityManager em;

    public List<Person> getAllPersons() {

        return 
            em.createQuery("SELECT p FROM T_Person p", Person.class).getResultList();

    }

}

存储

@Stateless
public class Storage {

    @EJB
    PersonDAO psDAO;

    private List<Entity> personList;

    public Storage() {
        personList = new ArrayList<Entity>();
    }

    @PostConstruct
     private void initSampleData(){
         psDAO.getAllPersons();
    }
}

PersonEntityCollectionProcessor：

public class PersonEntityCollectionProcessor implements EntityCollectionProcessor {

    private OData odata;
    private ServiceMetadata serviceMetadata;
    private Storage storage;

    public PersonEntityCollectionProcessor(Storage storage) {
        this.storage = storage;
    }

    public void init(OData odata, ServiceMetadata serviceMetadata) {
        this.odata = odata;
        this.serviceMetadata = serviceMetadata;
    }

}

Answer 1

我认为问题出在你的代码的这一部分：

    storage = (Storage) session.getAttribute(Storage.class.getName());
    if (storage == null) {
       storage = new Storage();
       session.setAttribute(Storage.class.getName(), storage);
    }

使用此方法，您可以创建Storage的非托管实例，而不是使用注入的实例，因此不会调用@PostConstruct。如果执行此代码时Storage通过@EJB注入的实例为null，则您可能会遇到注入问题。

你可以删除这5行，它应该工作。您不需要在会话中手动保存实例。

Answer 2

大多数EJB都是懒惰地初始化的，因此只有在实际使用该bean的实例时才会首先调用@PostConstruct。

那说;你永远不会在servlet的存储中使用实际的sessionbean，所以不需要调用@PostConstruct

您从会话中覆盖它，或重新创建它

(function($) {
    $(function() {
        $(".container").each(function() {
            var container = $(this);
            var gallery = container.children(".gallery");
            container.children(".info").appendTo(gallery);
            gallery.children(".thumbnails").appendTo(container);
        });
    });
})(jQuery);

没有调用EJB @PostConstruct

2 个答案: