ListenToValueEventsOnSubscribe.java 文件源码

@Override
public void call(Subscriber<? super T> subscriber) {
    final ValueEventListener eventListener = query.addValueEventListener(new RxValueListener<>(subscriber, marshaller));
    subscriber.add(BooleanSubscription.create(new Action0() {
        @Override
        public void call() {
            query.removeEventListener(eventListener);
        }
    }));
}