Java EE - dependency injection into batchlet

Question

I am having issues with dependency injection in a batchlet.

@Named
public class SimpleBatchlet extends AbstractBatchlet {
  @Inject
  protected StorageService storageService;

  ...

  public String process() throws Exception {
    storageService.doSomething(); // this throws a null pointer exception
  }
}

@Named
public class LocalFileStorageService implements StorageService {
   public void doSomething() {

   }
}

I have tried putting beans.xml in both META-INF and WEB-INF and removing it, all to no avail. I also tried changing the scopes of the beans to singletons, etc. I am invoking / starting the batch job through the use of an @Schedule annotation on a method that uses BatchRuntime to start the job.

I must be missing something simple as I know this should work. The actual scope of the beans I will use may need to vary, but the point I am trying to make is that I don't believe bean scope is a problem, but some other configuration issue.

I should also note that I only have 1 implementation of StorageService.

Answer 1

Not clear what really is your problem (NPE on injected CDI bean?), but annotating your Batchlet @Dependent should solve the problem :

@Named
@Dependent
public class SimpleBatchlet extends AbstractBatchlet {
  @Inject
  protected StorageService storageService;
}

Batchlet need to be @Named and @Dependent for integration with CDI.