FirebaseEntityStore.java 文件源码

private <T> Observable<T> getQuery(Query query, Action2<Subscriber<? super T>, DataSnapshot> onNextAction, boolean subscribeForSingleEvent) {
    return Observable.create(subscriber -> {
        ValueEventListener eventListener = new ValueEventListener() {

            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                onNextAction.call(subscriber, dataSnapshot);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                subscriber.onError(new FirebaseException(databaseError.getMessage()));
            }
        };
        if (subscribeForSingleEvent) {
            query.addListenerForSingleValueEvent(eventListener);
        } else {
            query.addValueEventListener(eventListener);
        }
        subscriber.add(Subscriptions.create(() -> query.removeEventListener(eventListener)));
    });
}