Comments on: Getting Started with CDI part 2 – Injection

By: Andy Gibson

Andy Gibson — Fri, 16 Jul 2010 22:55:23 +0000

You might also want to try out a set of Maven Archetypes I just released which in addition contains the usual starter projects, also has a project that implements a CRUD demo with just out-of-the-box Java EE 6.

You can find it at http://www.fluttercode.com/projects/knappsack/

By: Andy Gibson

Andy Gibson — Fri, 16 Jul 2010 22:53:12 +0000

Hey Herman,

Both type and and Qualifiers are used to match beans to injection points so a qualifier is just an additional criteria in case you have beans that implement the same interface.

For example, if you have multiple data source and inject the entity manager, you could qualify one with @WebStoreDb and the other with @DataWarehouseDb. Without a qualifier, we don’t know which to use where.

By: Herman Chung

Herman Chung — Fri, 16 Jul 2010 17:08:16 +0000

Btw, Thanks Andy for this article, it is very informative and easy to understand, i was having a hard time learning just by reading the Weld Docs

By: Herman Chung

Herman Chung — Fri, 16 Jul 2010 17:07:08 +0000

Maybe I am just confused or that I am very new to CDI, so the advantage of Qualifier is that it is typesafe (can apply to interface instead of using names which only applies to implementation)..

so we basically need to create multiple qualifers (meaning multiple classes) for each implementations of the interface we might want to inject?

This does seem kinda inconvenient..

By: Getting Started with Netbeans, JSF 2.0 and CDI part 1 | FlutterCode

Getting Started with Netbeans, JSF 2.0 and CDI part 1 | FlutterCode — Sun, 16 May 2010 03:06:24 +0000

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By: Robert, Austin, Texas

Robert, Austin, Texas — Sat, 10 Apr 2010 04:51:13 +0000

Thanks for the reply. Nope, it is not annotated @Stateless. Until I changed the bean to SessionScope I was copying and pasting from your examples, too. Go figure…

By: Andy Gibson

Andy Gibson — Fri, 09 Apr 2010 04:10:17 +0000

Is the item processor a stateless bean? If so, take off the @Stateless annotation. There is a problem with Weld 1.0 (and maybe 1.0.1) where stateless beans were considered not proxyable which is wrong because they don’t need to be proxied :

Here’s my post about it on the seam framework web site.

http://seamframework.org/Community/ProblemsWithStatelessBeansInWeldCR101CR2

You should be ok if you just remove the stateless annotation making it a non-EJB bean

Cheers,

Andy Gibson

By: Robert, Austin, Texas

Robert, Austin, Texas — Thu, 08 Apr 2010 22:22:01 +0000

… so, after making beans serializable, the passivation error no longer happens for session scoped ItemProcessor, but error “eedemo.ItemProcessor is not proxyable” is seen, as in the request scope case. It just doesn’t like constructor injection.

By: Robert, Austin, Texas

Robert, Austin, Texas — Thu, 08 Apr 2010 20:30:08 +0000

Andy,
Having the same problem as Fred has with not being able to do injection into a constructor:
“ItemProcessor is not proxyable”
I am running glassfish v3 in Netbeans 6.8 IDE.
in the case above ItemProcessor is request scoped.

If I change scope to session I see a different error involving the bean not being passivatable.

By: Andy Gibson

Andy Gibson — Sat, 20 Mar 2010 04:22:59 +0000

Yes, you do need to be careful since many of the annotations have similar names. It is really an annoyance that I don’t believe will go away any time soon.

However, thanks for posting, if nothing else, it might be a good idea to include some of the import statements in my code examples,

Thanks,

Andy