Answers in-line.
The fact that you are asking these questions implies that we do not have
enough documentation for the feature. I will try to find somewhere to
add an example or find some other way to upgrade the documentation.
On 8/7/2013 8:43 AM, buko wrote:
>
> Are there any examples of custom InstanceLifeCycleListeners out there?
We have no example of the InstanceLifeCycleListener in our
documentation. However, the config subsystem of HK2 uses it in order to
have a backwards reference from the injectee to the injector. I think
some kind of example should be added to the hk2 documentation.
>
> I'm looking to do some basic post-processing of managed objects. In
> the normal injection phase a resource is passed to the ctor. In the
> next phase I'd like to go back and use the injected resource to
> further customize the object.
>
> I've taken a look at ConfigInstanceListener and don't quite get it.
>
> Does the lifecycle object (post-processing target?) need to implement
> a specific interface in order for the Filter to match? Ideally I'd
> like to just slap an annotation on them. But it's not clear how to
> construct a Filter that matches an annotation.
If you just want to put an annotation on the classes you want to operate
on the best thing to do would be to make your annotation a qualifier
(i.e., put @Qualifier on your annotation). That way your annotation
would show up in the list of qualifiers in the Descriptor. And thus the
Filter could easily match just those services that have that qualifier.
>
> If I need to actually initialize/wrap/set fields on the lifecycle
> object does hk2 offer any facilities for that? Should normal java
> reflection be used? I'm worried this won't work if the post-processing
> object is proxied by hk2. Do InstanceLifeCycleListeners get called for
> the creation of proxies if the underlying object hasn't been created yet?
You would need to do your own reflection. The object returned here is
NOT the proxy, but the real underlying object, which means you can call
any methods you want on the object and not worry about causing the proxy
to create the underlying object (thus invalidating the point of the
proxy!). This fact should be documented in the javadoc though!
>
> What does InstanceLifeCycleEvent#knownInjectees return? Are these the
> same injectees that are passed to a custom InjectionResolver?
For this the javadoc is pretty clear. The descriptor has a set of
injectees. This is a map from that set of injectees to the real objects
that were created for this object. This is useful in the usecase
described above, where the user wants to have a backwards pointer from
the injectee to the injector.
>
> Thanks for any help.