The reason you're getting NPE's is that your instances of APICommand are
not themselves injected by the container (you are instantiating them in
code somewhere...indicated by the fact that APICommand has a
non-injected parameterized constructor).
Dan
On Sat, 2013-02-23 at 11:59 +0000, c.whalley wrote:
> I have a rather long servlet which I'm trying to refactor such that
> separate helper objects perform the same work. The trouble is, I think
> I'm missing some config setting because the same working code from the
> servlet gives npe's when moved to another class. What's special about
> having these annotation in the servlet class (where ultimately I don't
> want them anyway)? The problem is the "ut" instance in the ut.begin();
> line of APICommand below is null, whereas in the APIServlet it's fine.
>
> Thanks.
>
> ----------------------------------------------
> Servlet definition:
>
> @WebServlet(value="/api", name="api-servlet")
> public class APIServlet extends HttpServlet {
>
> @PersistenceUnit(unitName="my_persistence_unit")
> private EntityManagerFactory emf;
> private EntityManager em;
>
> @Inject
> private UserTransaction ut;
>
> public void service(HttpServletRequest req, HttpServletResponse
> res) throws IOException, ServletException {
> PrintWriter out = res.getWriter();
> res.setContentType("text/html");
>
> User user = new User();
> user.setName("foo");
> update(user);
> ...
> }
>
> private void update(User user) {
> try {
> ut.begin();
> em = emf.createEntityManager();
> ...
> em.persist(userToPersist);
> em.flush();
> } catch (Exception e) {
> ...
> } finally {
> try {
> ut.commit();
> } catch (Exception commitEx) {
> ...
> }
> }
> }
> }
>
> Helper class definition:
> ----------------------------------------------
> public class APICommand {
>
> @PersistenceUnit(unitName="my_persistence_unit")
> private EntityManagerFactory emf;
> private EntityManager em;
>
> @Inject
> private UserTransaction ut;
>
> public APICommand(HttpServletRequest req) throws IOException {
> api = API.findAPI(req);
> }
>
> public String execute() {
> if (api.isValid()) {
> if (api == API.EXAMPLE) {
> User user = new User();
> user.setName("foo");
> update(user);
> }
> }
> }
>
> private void update(User user) {
> try {
> ut.begin();
> em = emf.createEntityManager();
> ...
> em.persist(userToPersist);
> em.flush();
> } catch (Exception e) {
> ...
> } finally {
> try {
> ut.commit();
> } catch (Exception commitEx) {
> ...
> }
> }
> }
> }
>
>
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>
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