我正在制作帶有firebase firestore數(shù)據(jù)庫的Android聊天應(yīng)用程序，我需要與偵聽器進(jìn)行無限分頁以進(jìn)行數(shù)據(jù)更改（新按摩，刪除按摩...我發(fā)現(xiàn)用kotlin和corse搜索的firebase文檔寫的博客文章，最終得到了這個(gè)代碼： // firstTime variable shows if function is called from pagination or initially private void addMessagesEventListener(boolean firstTime) { // get collection CollectionReference messagesCollection = chatsCollection.document(chat.getId()).collection(Constants.FIREBASE_MESSAGES_PATH); // create query Query query = messagesCollection.orderBy("timestamp", Query.Direction.DESCENDING); // if NOT first time add startAt if (!firstTime) { query.startAt(startTimestamp); } //limit to 20 messages query.limit(20).get().addOnSuccessListener(queryDocumentSnapshots -> { if (!firstTime) { endTimestamp = startTimestamp; } startTimestamp = (long) queryDocumentSnapshots.getDocuments().get(queryDocumentSnapshots.size() - 1).get("timestamp"); Query innerQuery = messagesCollection.orderBy("timestamp").startAt(startTimestamp); if(!firstTime) { innerQuery.endBefore(endTimestamp); } ListenerRegistration listener = innerQuery .addSnapshotListener((queryDocumentSnapshots1, e) -> { if (e != null) { Log.w(TAG, "listen:error", e); return; }
2 回答
慕姐8265434
TA貢獻(xiàn)1813條經(jīng)驗(yàn) 獲得超2個(gè)贊
試試這個(gè)
@Override
public void onStart() {
super.onStart();
loadFirstQuery();
}
public void loadFirstQuery() {
if (firebaseAuth.getCurrentUser() != null) {
contentListDashboard.clear();
String currentUserId = firebaseAuth.getCurrentUser().getUid();
// what we do when recycler reach bottom
recyclerProfileDashboard.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
// horizontal
//Boolean reachBottom = !recyclerView.canScrollHorizontally(-1);
// for vertical recycler
Boolean reachBottom = !recyclerView.canScrollVertically(-1);
if (reachBottom) {
loadMorePost(); // do load more post
}
}
});
// RETRIEVING FIRST Query
Query firstQuery = firebaseFirestore
.collection("ProfileDashboard")
.document(currentUserId)
.collection("ProfileInfo")
.orderBy("timestamp", Query.Direction.DESCENDING)
.limit(20);
firstQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
if (!documentSnapshots.isEmpty()) {
// please add if doc not empty
if (isFirstPageFirstLoad) {
lastVisible = documentSnapshots.getDocuments().get(documentSnapshots.size() - 1); // array 0, 1, 2
}
for (DocumentChange doc : documentSnapshots.getDocumentChanges()) {
if (doc.getType() == DocumentChange.Type.ADDED) {
//String postId = doc.getDocument().getId();
contentProfileDashboard = doc.getDocument().toObject(ContentProfileDashboard.class);
// if first page firest load true
if (isFirstPageFirstLoad) {
contentListDashboard.add(contentProfileDashboard);
} else {
contentListDashboard.add(0, contentProfileDashboard);
}
// fire the event
adapterProfileDashboard.notifyDataSetChanged();
}
}
isFirstPageFirstLoad = false;
}
}
});
}
}
// Method to load more post
public void loadMorePost() {
if (firebaseAuth.getCurrentUser() != null) {
String currentUserId = firebaseAuth.getCurrentUser().getUid();
Query nextQuery = firebaseFirestore
.collection("ProfileDashboard")
.document(currentUserId)
.collection("ProfileInfo")
.orderBy("timestamp", Query.Direction.DESCENDING)
.startAfter(lastVisible)
.limit(20);
nextQuery.addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
if (!documentSnapshots.isEmpty()) {
lastVisible = documentSnapshots.getDocuments().get(documentSnapshots.size() - 1);
for (DocumentChange doc : documentSnapshots.getDocumentChanges()) {
if (doc.getType() == DocumentChange.Type.ADDED) {
//String postId = doc.getDocument().getId();
// contentSeen = doc.getDocument().toObject(ContentProfile.class);
// contentList.add(contentSeen);
contentProfileDashboard = doc.getDocument().toObject(ContentProfileDashboard.class);
contentListDashboard.add(contentProfileDashboard);
//adapterSeen.notifyDataSetChanged();
adapterProfileDashboard.notifyDataSetChanged();
}
}
}
}
});
}
}
任何問題？
白豬掌柜的
TA貢獻(xiàn)1893條經(jīng)驗(yàn) 獲得超10個(gè)贊
我發(fā)現(xiàn)了錯(cuò)誤。工作代碼是：
private void addMessagesEventListener(boolean firstTime) {
CollectionReference messagesCollection = chatsCollection.document(chat.getId()).collection(Constants.FIREBASE_MESSAGES_PATH);
Query query = messagesCollection.orderBy("timestamp", Query.Direction.DESCENDING);
if (!firstTime) {
query = query.startAt(startListen);
}
query.limit(20).get().addOnSuccessListener(queryDocumentSnapshots -> {
if (!firstTime) {
endListen = startListen;
}
startListen = queryDocumentSnapshots.getDocuments().get(queryDocumentSnapshots.size() - 1);
Query innerQuery = messagesCollection.orderBy("timestamp").startAt(startListen);
if(!firstTime) {
innerQuery = innerQuery.endBefore(endListen);
}
ListenerRegistration listener = innerQuery
.addSnapshotListener((queryDocumentSnapshots1, e) -> {
if (e != null) {
Log.w("SASA", "listen:error", e);
return;
}
for (DocumentChange dc : queryDocumentSnapshots1.getDocumentChanges()) {
Message message = dc.getDocument().toObject(Message.class);
switch (dc.getType()) {
case ADDED:
// add new message to list
messageListAdapter.addMessage(message);
if (firstTime) {
messagesList.smoothScrollToPosition(0);
}
break;
case REMOVED:
// remove message from list
messageListAdapter.removeMessage(message);
break;
}
}
});
listeners.add(listener);
});
}
錯(cuò)誤在于query = query.startAt(startListen)innerQuery = innerQuery.endBefore(endListen)
startListen & endListen 是 DocumentSnapshot type
我正在使用 sortedList 在我的適配器中
你應(yīng)該添加
private void detachListeners() {
for(ListenerRegistration registration : listeners) {
registration.remove();
}
}
在 onDestroy 中分離所有偵聽器。
代碼正在偵聽添加新消息和刪除舊消息。
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