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http://issues.ops4j.org/browse/QI-266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572#action_13572
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Niclas Hedhman commented on QI-266:
-----------------------------------
Rickard wrote on mailing list;
The @Service injection has so far only been able to specify the type of the
service to be injected. If any other type of qualification had to be done it
was to be done through a ServiceSelector. This works, but for common cases it
would be more convenient to use annotations to do this filtering. I have now
updated the ServiceSelector API quite a bit, and at the same time implemented
annotation support to perform this qualification.
Example:
@Service @Tagged("sometag") MyService service;
This will only inject instances of MyService that have been tagged with
"sometag". If none exist an exception will occur at injection time since it is
not optional.
It also works with iterables:
@Service @Tagged("sometag") Iterable<MyService> services;
The qualification will be evaluated upon each call to iterator(), and since the
qualifier has access to a ServiceReference, which contains the isActive()
method, it can even provide some dynamicity. Example:
@Service @Active Iterable<SomeImportedService> importedServices;
Let's say these SomeImportedService are only sometimes available. Then whenever
iterator() is called the @Active tag can kick in and filter out those whose
ServiceReference.isActive() returns false.
See tests and API for more examples, and how to implement your own qualifiers.
Standard ones I've defined in the API are:
@Tagged
@IdentifiedBy
@Active
> Introduction of Service Qualifier API
> -------------------------------------
>
> Key: QI-266
> URL: http://issues.ops4j.org/browse/QI-266
> Project: Qi4j
> Issue Type: New Feature
> Components: API
> Reporter: Niclas Hedhman
> Assignee: Rickard Öberg
> Fix For: 1.2
>
>
> The @Service injection has so far only been able to specify the type of the
> service to be injected. If any other type of qualification had to be done it
> was to be done through a ServiceSelector. This works, but for common cases it
> would be more convenient to use annotations to do this filtering.
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