Inject a Java object in a JSF Named bean

Question

I have a JSF2 bean used as a controller for my view:

@Named
@SessionScoped
public class PosController implements Serializable {

  @EJB FatturaFacade fatturaFacade;

  // ...
}

As you can see I already can inject one of my EJBs (used as a dao wrapper) inside it, but what's the way for injecting a "simple" object? And what if I have different implementations as follows?

interface Retriever;
class WebServiceRetriever implements Retriever;
class FileRetriever implements Retriever;

I saw the @interface annotation, but I didn't understand it well.

Answer 1

Assuming you have a full Java EE 6 platform the best approach is to use CDI's @Inject.

The simplest mechanism would be to use the concrete types:

public class Bean {
  @Inject
  private WebServiceRetriever webServiceRetriever;

  @Inject
  private FilesRetriever filesRetriever;

  //etc.

For multiple implementations of the same interface you can create @Qualifier annotations. Their usage is explained in the Using Qualifiers section of the Java EE 6 tutorial.

A @Files qualifier:

@Qualifier
@Retention(RUNTIME)
@Target({TYPE, METHOD, FIELD, PARAMETER})
public @interface Files {}

The FileRetriever implementation:

@Files
public class FileRetriever implements Retriever {}

Disambiguation of the Retriever implementations in the injection target:

public class Bean {
  @Inject @WebServices
  private Retriever webServiceRetriever;

  @Inject @Files
  private Retriever filesRetriever;

  //etc.

There is a post on my blog on using JSF with CDI that you might find useful.