Hi,
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
/Rickard
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