Why can't I use @EJB with @Named?

Question

I basically am trying to inject a @Stateless bean with a local interface into a class annotated with @Named! My understanding is that injection is only possible when the injection point is managed (makes perfect sense), so for example it wouldn't be possible to inject into a POJO but you could inject into a Servlet, a JSF managed or another EJB.

I would have thought that it would have been possible to subsequently use it with @Named! However I get a NullPointerException that specifically seems to imply that this in fact doesn't seem possible!?

My classes look like this (stripped for clarity);

@Named
public class EmailUtil {

// Logger-------------------------------------------------------------------
private static final Logger LOG = Logger.getLogger(EmailUtil.class.getName());

// Constructor--------------------------------------------------------------
public EmailUtil() {
}

// EJB----------------------------------------------------------------------
@EJB AuditDAO audit;

// Methods------------------------------------------------------------------
public void sendEmail(
        String emailSender,
        String emailRecipient,
        String emailSubject,
        String emailHtmlBody,
        String emailTextBody) throws FailedEmailException {

    ... code removed for clarity ...

    // Call Amazon SES to send the message 
    try {
        new SES().getClient().sendEmail(request);

        // Create an audit log of the event
        audit.create("Email sent to " + emailSender);
    } catch (AmazonClientException ace) {
        LOG.log(Level.SEVERE, ace.getMessage(), ace);
        throw new FailedEmailException();
    } catch (Exception e) {
        LOG.log(Level.SEVERE, e.getMessage(), e);
    }
}
}


@Stateless
public class AuditDAOImpl implements AuditDAO {

    // Logger-------------------------------------------------------------------
    private static final Logger LOG = Logger.getLogger(AuditDAOImpl.class.getName());
    // EntityManager------------------------------------------------------------
    @PersistenceContext(unitName = "iConsultPU")
    private EntityManager em;

    @Override
    public void create(String event) {
        String subject;
        try {
            /*
             * If the current subject has authenticated and created a session we
             * want to register their ID. However it is possible that a subject
             * does not have an ID so we want to set it to unknown.
             */
            subject = SecurityUtils
                    .getSubject()
                    .getPrincipals()
                    .asList()
                    .get(1)
                    .toString();
        } catch (Exception e) {
            subject = "UNKNOWN";
        }

        Audit audit = new Audit();
        audit.setUserId(subject);
        audit.setEventTime(Calendar.getInstance());
        audit.setEvent(event);

        em.persist(audit);

    }
}

@Local
public interface AuditDAO {
    public void create(String event);    
}

I've tried using @Inject as well but that doesn't seem to work either. Have I misunderstood the specification or just poorly implemented it?

Answer 1

You should be injecting your dependencies. So if your EmailUtil is being manually constructed, injection won't work. It needs to be container managed. So if you use a servlet, or any managed bean, you can @Inject it. CDI injection only works for managed objects.

You can do some additional work arounds, such as manually invoking it against a constructed instance. Take a look at this question for an example like that: Parallel webservices access in a Weld CDI environment

Answer 2

Do you have the beans.xml in the correct location? Injection for @Named (and other CDI beans) is handled by CDI, which isn't started unless you have the beans.xml file in the correct location (WEB-INF for war and META-INF for jar).