Database Reference
In-Depth Information
about the channels assigned to this source as well as any other properties
that might have been set in the configuration:
public void
configure(Context context) {
Interacting with the context object is quite simple. There are a number
of “getters” defined on the context class that can be used to extract
configuration parameters. These properties have already been specialized
to the appropriate selector. For example, if the class needed to access the
“optional”
property, like the replicating selector, then the following code
would get the string associated with the property:
String optionalList = context.getString("optional");
However,
RandomSelector
only needs the list of channels associated with
this source. This method,
getAllChannels
, is actually part of the
AbstractChannelSelector
class, so it is called directly. Because the
RandomSelector
sends each event to one channel, list elements are
constructed for later use:
for
(Channel c : getAllChannels()) {
List<Channel> x =
new
ArrayList<Channel>();
x.add(c);
outputs.add(x);
}
The other two methods that must be implemented by a custom channel
selector are
getRequiredChannels
and
getOptionalChannels
. Each
method gets a single argument in the form of an
Event
, whose metadata
can be checked. The
RandomSelector
does not check metadata; it simply
returns a random array containing a single channel as constructed in the
configuration method:
public
List<Channel> getRequiredChannels(Event event) {
return
outputs.get(rng.nextInt(outputs.size()));
}
public
List<Channel> getOptionalChannels(Event event) {
return
empty;
}
