Firebase android how to get data from List of keys at once

问题

I am using firebase geofire library to fetch key's based on location but because of thousands of keys are returned in onKeyEntered() event every time I have to take the key refer firebase and get the object back and set it to listview becoming very slow. I tried commenting all other work in onKeyEntered() to see how fast geofire is then I was surprised withing 900 milli's all callbacks received.

So now what is the best optimized way to get the data from firebase using the key passed in onKeyEntered() callback and set it to listview so that even for thousands of entries listview should load fast

I thought of AsyncTask in every callback give the fetching data work to AsyncTask and proceed with next callback key and do same, but not sure thats correct.

Or load only few and then load as scroll's is also good idea but geofire returns keys from all over the database so there is no option to get only few latest one so not sure how to implement it.

This is what I am trying but list view loads very slow.

  @Override
public void onKeyEntered(String key, GeoLocation location) {
    Log.d("geoevent", key);
    mDatabaseTemp = FirebaseDatabase.getInstance().getReference("/posts/" + key);
    mDatabaseTemp.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Post post = new Post();
            post = dataSnapshot.getValue(Post.class);
            mPosts.add(post);
            mPostAdapter.notifyDataSetChanged();
            mRecycler.smoothScrollToPosition(mPosts.size() - 1);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            Toast.makeText(getActivity(), "error" + databaseError, Toast.LENGTH_LONG).show();

        }
    });
}

回答1:

Question of the type "how to best" are notoriously difficult to answer. But I'll give a few hints about the general behavior of the system that you may not be aware of.

1. the Firebase Database client interacts with the network and disk on a separate thread. When data is available for your client, it calls your handlers on the main/UI thread. This means that putting your calls in an AsyncTask is only useful if you'll be doing significant work in the callback.
2. the Firebase Database client pipelines the calls to the server over a single connection. To read more about why that affects performance, see Speed up fetching posts for my social network app by using query instead of observing a single event repeatedly.
3. loading thousands of items into a mobile device over the network is in general not a good idea. You should only load data that you'll show to the user and thousands of items is well beyond what can be reasonably presented on a mobile screen. When developing a location based app, you could show a map where the user indicates a hotspot and you use Geoqueries to only request items around that spot.

来源：https://stackoverflow.com/questions/38506631/firebase-android-how-to-get-data-from-list-of-keys-at-once