Okay, so there is an explicit step that must be taken for a producer method
to win over a @Current bean (does not have additional bindings) of that
type. I suspect in most cases developers will choose to use the binding type
since that is the type-safe approach.
The designation of the alternative class in beans.xml makes all producer
methods in that class have a higher precedence than any @Current bean of
that type, correct? Is it also possible to specify a single method in
beans.xml? There is alluded to in the Policy section, but no examples to
support it.
Btw, I think this would be a lot clearer if it was explicitly stated in the
spec how a producer method relates to a @Current bean of that type. I guess
you could say it can be implied, but the first time someone goes to create a
producer method, I can see them not realizing that they have to take an
extra step to make it the preferred source.
-Dan
On Wed, Jul 22, 2009 at 7:13 AM, Pete Muir <pmuir(a)redhat.com> wrote:
On 22 Jul 2009, at 03:18, Dan Allen wrote:
After the recent revisions of the JSR-299 spec, I'm finding that I'm a tad
> confused about the bean selection algorithm when a producer method exists.
>
> Consider the following:
>
> class PotatoChip {
> }
>
> class SnackFactory() {
> public @Produces PotatoChip createPotatoChip() {
> return new PotatoChip();
> }
> }
>
> 1) Does the produced PotatoChip take precedence over the raw dependent
> type when being selected for injection?
>
No.
> 2) How do I get the Bean<PotatoChip> that represents the producer method?
>
> BeanManager#getBeans(PotatoChip.class) returns two beans that are
> indistinguishable from the public API.
>
either:
@Alternative
class SnackFactory() {
public @Produces PotatoChip createPotatoChip() {
return new PotatoChip();
}
}
<beans>
<alternatives>
<alternative>SnackFactory</alternative>
</alternatives>
</beans>
or
class SnackFactory() {
public @Produces @Snack PotatoChip createPotatoChip() {
return new PotatoChip();
}
}
BeanManager.getBeans(PotatoChip.class, new AnnotationLiteral<Snack>() {});
where @Snack is a binding type
> 3) What if the producer method is @RequestScoped? How do I get the
> request-scoped produce instead of the dependent bean?
>
> Bean<PotatoChip> potatoChipBean = null;
> for (Bean<PotatoChip> candidate : getBeans(PotatoChip.class))
> {
> if (candidate.getScopeType().equals(RequestScoped.class))
> {
> potatoChipBean = candidate;
> break;
> }
> }
>
> Sorry if this sounds like a dumb question. The spec has changed a lot and
> my memory is getting mixed in with the current set of facts.
>
As above.
It's possible the RI doesn't actually reflect this behavior atm - if you
have a problem, make sure there is a test, then change the RI or file a
WBRI.
--
Dan Allen
Senior Software Engineer, Red Hat | Author of Seam in Action
Registered Linux User #231597
http://mojavelinux.com
http://mojavelinux.com/seaminaction
http://in.relation.to/Bloggers/Dan