Java Query类代码示例

import com.firebase.client.Query; //导入依赖的package包/类
private void renderData() {
    Query queryRef = mRootRef.child("users").orderByChild(getOrderBy()).limitToLast(100);//we need to iterate them backwards
    queryRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {

            for (DataSnapshot userSnapshot : snapshot.getChildren()) {
                mUsersDataset.add(userSnapshot.getValue(User.class));
            }
            Collections.reverse(mUsersDataset);
            mAdapter = new UserListAdapter(mUsersDataset, getActivity(), getmTabType());
            mRecyclerView.setAdapter(mAdapter);
            mLoadingWrapper.setVisibility(View.GONE);
            mRecyclerView.setVisibility(View.VISIBLE);
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });
}
 

import com.firebase.client.Query; //导入依赖的package包/类
public static Observable<DataSnapshot> observeOnce(final Query ref){
    return Observable.create(new Observable.OnSubscribe<DataSnapshot>() {
        @Override
        public void call(final Subscriber<? super DataSnapshot> subscriber) {
            ref.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    subscriber.onNext(dataSnapshot);
                    subscriber.onCompleted();
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {
                    subscriber.onError(new FirebaseException(firebaseError));
                }
            });
        }
    });
}
 

import com.firebase.client.Query; //导入依赖的package包/类
private void setupStoriesAdapter(Query query) {
    InfiniteFireArray<Story> storyFireArray = new InfiniteFireArray<>(Story.class
            , query, 10, 10, false, false);

    storiesAdapter = new StoriesAdapter(storyFireArray, publicType);
    storiesAdapter.setHasStableIds(true);
    storiesAdapter.registerAdapterDataObserver(storiesAdapterObserver);

    if(needsUserPublish()) storiesAdapter.setUser(user);

    storiesAdapter.setOnStoryViewListener(this);
    storiesAdapter.setOnNewsViewListener(this);
    storiesAdapter.setOnShareNewsListener(this);
    storiesAdapter.setOnPublishStoryListener(onPublishStoryListener);
    storiesAdapter.setOnUserStartChattingListener(onUserStartChattingListener);
    storiesAdapter.setOnNeedUpdateStoryListener(this);
    storiesList.setAdapter(storiesAdapter);
    storiesList.setInfiniteFireArray(storyFireArray);

    if (newsList != null) {
        storiesAdapter.addNews(newsList);
    }
}
 

import com.firebase.client.Query; //导入依赖的package包/类
public ValueEventListener loadLastChatMessage(final ChatRoomHolder holder
        , final ChatRoomInterface.OnChatLastMessageLoadedListener onChatLastMessageLoadedListener) {
    Query query = getDefaultRoot().child(messagesPath).child(holder.chatRoom.getKey()).orderByKey().limitToLast(1);
    return query.addValueEventListener(new ValueEventListenerAdapter() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            super.onDataChange(dataSnapshot);

            Log.d(TAG, "onDataChange() called with: " + "dataSnapshot = [" + dataSnapshot + "]");
            if (dataSnapshot.exists() && dataSnapshot.getChildrenCount() > 0) {
                ChatMessage lastChatMessage = dataSnapshot.getChildren().iterator().next().getValue(ChatMessage.class);
                if (lastChatMessage != null) {
                    lastChatMessage.setKey(dataSnapshot.getKey());
                    int indexOfUser = holder.members.getUsers().indexOf(lastChatMessage.getUser());
                    if (indexOfUser >= 0) {
                        lastChatMessage.setUser(holder.members.getUsers().get(indexOfUser));
                    }
                    holder.lastMessage = lastChatMessage;
                }
                onChatLastMessageLoadedListener.onChatLastMessageLoaded(lastChatMessage);
            } else {
                onChatLastMessageLoadedListener.onChatLastMessageLoadFailed();
            }
        }
    });
}
 

import com.firebase.client.Query; //导入依赖的package包/类
public static Observable<DataSnapshot> observe(final Query ref) {

        return Observable.create(new Observable.OnSubscribe<DataSnapshot>() {

            @Override
            public void call(final Subscriber<? super DataSnapshot> subscriber) {
                final ValueEventListener listener = ref.addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        subscriber.onNext(dataSnapshot);
                    }

                    @Override
                    public void onCancelled(FirebaseError error) {
                        // Turn the FirebaseError into a throwable to conform to the API
                        subscriber.onError(new FirebaseException(error.getMessage()));
                    }
                });

                // When the subscription is cancelled, remove the listener
                subscriber.add(Subscriptions.create(() -> ref.removeEventListener(listener)));
            }
        });
    }
 

import com.firebase.client.Query; //导入依赖的package包/类
public static Observable<DataSnapshot> observeOnce(final Query ref) {

        return Observable.create(new Observable.OnSubscribe<DataSnapshot>() {

            @Override
            public void call(final Subscriber<? super DataSnapshot> subscriber) {
                ref.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        subscriber.onNext(dataSnapshot);
                        subscriber.onCompleted();
                    }

                    @Override
                    public void onCancelled(FirebaseError error) {
                        // Turn the FirebaseError into a throwable to conform to the API
                        subscriber.onError(new FirebaseException(error.getMessage()));
                        subscriber.onCompleted();
                    }
                });
            }
        });
    }
 

import com.firebase.client.Query; //导入依赖的package包/类
@Override
public Post[] getPosts(int numPosts) {
    Query query = firebasePostsRef.orderByChild("timestamp").limitToLast
            (numPosts);

    countDownLatch = new CountDownLatch(1);

    ValueEventListener callbackListener =
            newValueEventListenerForSynchronizingCallback();
    query.addListenerForSingleValueEvent(callbackListener);

    waitForCallback();

    if (dataFromCallback != null) {
        return parsePostsFromDataSnapshot(dataFromCallback.get());
    } else {
        return new Post[0];
    }
}
 

import com.firebase.client.Query; //导入依赖的package包/类
@Override
public Post[] getPostsByUser(String userId) {
    Query query = firebasePostsRef.orderByChild("authorId").equalTo(userId);

    countDownLatch = new CountDownLatch(1);

    ValueEventListener callbackListener =
            newValueEventListenerForSynchronizingCallback();
    query.addListenerForSingleValueEvent(callbackListener);

    waitForCallback();

    if (dataFromCallback != null) {
        return parsePostsFromDataSnapshot(dataFromCallback.get());
    } else {
        return new Post[0];
    }
}
 

import com.firebase.client.Query; //导入依赖的package包/类
/**
 * @param clazz Class Reference for the type to deserialize {@link DataSnapshot}s into.
 * @param auther Authenticator
 * @param query Any {@link Query} reference.
 * @param listenForChildEvents Adds a {@link ChildEventListener} during runtime
 * @param listenForValueEvents Adds a {@link ValueEventListener} during runtime
 */
protected FirebaseSource(
    Class<T> clazz,
    FirebaseAuthenticator auther,
    Query query,
    boolean listenForChildEvents,
    boolean listenForValueEvents){
  if (query.toString().equals(query.getRef().getRoot().toString())){
    throw new IllegalArgumentException("Cannot use a reference to the root of a Firebase "
        + "repository. Since FirebaseSource uses a ref at the root of the repository to store"
        + "timestamps, this will result in an endless event loop, which will livelock your"
        + "pipeline.");
  }
  this.clazz = clazz;
  this.auther = auther;
  this.queryString = query.getRef().toString();
  this.listenForChildEvents = listenForChildEvents;
  this.listenForValueEvents = listenForValueEvents;
}
 

import com.firebase.client.Query; //导入依赖的package包/类
/**
 * @param query     The Firebase location to watch for data changes.
 *                  Can also be a slice of a location, using some combination of
 *                  <code>limit()</code>, <code>startAt()</code>, and <code>endAt()</code>.
 * @param itemClass The class of the items.
 * @param items     List of items that will load the adapter before starting the listener.
 *                  Generally null or empty, but this can be useful when dealing with a
 *                  configuration change (e.g.: reloading the adapter after a device rotation).
 *                  Be careful: keys must be coherent with this list.
 * @param keys      List of keys of items that will load the adapter before starting the listener.
 *                  Generally null or empty, but this can be useful when dealing with a
 *                  configuration change (e.g.: reloading the adapter after a device rotation).
 *                  Be careful: items must be coherent with this list.
 */
public FirebaseRecyclerAdapter(Query query, Class<T> itemClass,
                               @Nullable ArrayList<T> items,
                               @Nullable ArrayList<String> keys) {
    this.mQuery = query;
    if (items != null && keys != null) {
        this.mItems = items;
        this.mKeys = keys;
    } else {
        mItems = new ArrayList<T>();
        mKeys = new ArrayList<String>();
    }
    this.mItemClass = itemClass;
    query.addChildEventListener(mListener);
}
 

import com.firebase.client.Query; //导入依赖的package包/类
private Query getQuery() {
    if (query == null) {
        query = createQuery(firebaseRef);
    }

    return query;
}
 

import com.firebase.client.Query; //导入依赖的package包/类
public static Observable<DataSnapshot> observe(final Query ref) {

        return Observable.create(new Observable.OnSubscribe<DataSnapshot>() {

            @Override
            public void call(final Subscriber<? super DataSnapshot> subscriber) {
                final ValueEventListener listener = ref.addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        subscriber.onNext(dataSnapshot);
                    }

                    @Override
                    public void onCancelled(FirebaseError error) {
                        subscriber.onError(new FirebaseException(error));
                    }
                });

                subscriber.add(Subscriptions.create(new Action0() {
                    @Override
                    public void call() {
                        ref.removeEventListener(listener);
                    }
                }));
            }
        });
    }
 

import com.firebase.client.Query; //导入依赖的package包/类
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    setupObjects();
    setupView(view);
    Query query = loadData();
    setupStoriesAdapter(query);
}
 

import com.firebase.client.Query; //导入依赖的package包/类
private void setupMessagesAdapter() {
    Query query = chatRoomServices.getChatMessagesQuery(chatRoom.getKey());
    chatMessageArray = new InfiniteFireArray<>(ChatMessage.class, query, 20, 20, false, false);
    adapter = new ChatMessagesAdapter(user, chatMessageArray);
    adapter.setOnChatMessageSelectedListener(this);
    adapter.registerAdapterDataObserver(adapterDataObserver);

    messagesList.setAdapter(adapter);
    messagesList.setInfiniteFireArray(chatMessageArray);
}
 

import com.firebase.client.Query; //导入依赖的package包/类
private ValueEventListener loadUsers(final OnLoadAllUsersListener onLoadAllUsersListener, Query query) {
    ValueEventListener listener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            handleDataResponse(dataSnapshot, onLoadAllUsersListener);
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {}
    };
    query.addValueEventListener(listener);
    return listener;
}