Java Reference
In-Depth Information
messageB.setMessage("This is message B");
System.out.println("Start service call " + messageA.getMessage());
System.out.println("Start service call " + messageB.getMessage());
}
}
In the
EventService
class shown in Listing 6-15, the containers inject the two beans produced by
the factory into the
messageA
and
A messageB
member variables of the
EventService
class. You can
use these objects as you would normally.
An alternative implementation is to use the
@Qualifier
and
@interface
annotations to mark the
type you want to inject. The example that follows uses custom annotations to create two qualii ers:
@LongMessage
in Listing 6-16 and
@ShortMessage
in Listing 6-17.
LISTING 6‐16:
ShortMessage qualii er
@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.FIELD})
public @interface
ShortMessage
{}
LISTING 6‐17:
LongMessage qualii er
@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.FIELD})
public @interface
LongMessage
{}
You use these qualii ers to annotate the producer methods as shown in Listing 6-18 and their
matching injection points as shown in Listing 6-19.
LISTING 6‐18:
Using the qualii ers to disambiguate the beans
public class EventProducer {
@Produces
@ShortMessage
private MessageA messageAFactory(){
return new MessageA();
}
@Produces
@LongMessage
private MessageB messageBFactory(){
return new MessageB();
}
}
