पर जांच कर सकते हैं इस पर खुला स्रोत नमूना अनुप्रयोग के साथ एक पूरा गाइड लिखा है यह मैं कैसे firebase डेटाबेस से पृष्ठांकन लागू किया है। अगर हमारे पास 100 संदेश हैं तो एक मामले पर विचार करें। तो मैं पहले फायरबेस से पिछले 20 संदेशों को लोड करता हूं यानी 81 से 100 तक। फिर स्क्रॉल अप पर मैं getMoreMessages() फ़ंक्शन को अगले 20 संदेशों को लोड करने के लिए कॉल करता हूं जो 61 से 80 हैं और इसी तरह।
public class ChatActivity extends Activity {
String chat_id = "";
long mTotalChildren = 0;
boolean loading = false;
ChildEventListener childEventListenerMain, childEventListenerPager;
ChatActivity mContext = ChatActivity.this;
MessageAdapter messageAdapter;
@BindView(R.id.pb_messages)
ProgressBar pb_messages;
@BindView(R.id.ll_audio)
LinearLayout llAudio;
@BindView(R.id.tv_record_time)
AppCompatTextView tvRecordTime;
@BindView(R.id.tv_cancel)
AppCompatTextView tvCancel;
@BindView(R.id.iv_send)
AppCompatImageView ivSend;
@BindView(R.id.iv_record)
AppCompatImageView ivRecord;
@BindView(R.id.ab_layout)
AppBarLayout abLayout;
@BindView(R.id.messages)
RecyclerView rvMessages;
@BindView(R.id.iv_chat_icon)
SimpleDraweeView ivChatIcon;
@BindView(R.id.iv_camera)
AppCompatImageView ivCamera;
@BindView(R.id.iv_gallery)
AppCompatImageView ivGallery;
@BindView(R.id.message_input)
AppCompatEditText messageInput;
@BindView(R.id.tv_send)
AppCompatTextView tvSend;
@BindView(R.id.toolbar_title)
AppCompatTextView toolbarTitle;
@BindView(R.id.toolbar_status)
AppCompatTextView toolbarStatus;
@BindView(R.id.ll_send)
LinearLayout llSend;
int categoryId, senderId, receiverId, offerId;
String mLastKey;
LinearLayoutManager layoutManager;
private ArrayList<MessageModel> messageArrayList = new ArrayList<>();
private ArrayList<MessageModel> tempMessageArrayList = new ArrayList<>();
@Override
public int getLayoutId() {
return R.layout.activity_chat;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
messageAdapter = new MessageAdapter(mContext, messageArrayList) {
};
layoutManager = new LinearLayoutManager(mContext);
rvMessages.setLayoutManager(layoutManager);
rvMessages.setItemAnimator(new DefaultItemAnimator());
rvMessages.setAdapter(messageAdapter);
rvMessages.setHasFixedSize(true);
rvMessages.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (messageArrayList.size() >= 20 &&
!loading && layoutManager.findFirstVisibleItemPosition() == 0 && messageArrayList.size() < mTotalChildren) {
loading = true;
getMoreMessages();
}
}
});
messageAdapter.notifyDataSetChanged();
//used to scroll up recyclerview when keyboard pops up
rvMessages.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View view, int left, int top, int right, int bottom,
int oldLeft, int oldTop, int oldRight, int oldBottom) {
if (bottom < oldBottom) {
rvMessages.postDelayed(new Runnable() {
@Override
public void run() {
rvMessages.scrollToPosition(messageArrayList.size() - 1);
}
}, 100);
}
}
});
loading = true;
getMessages();
}
public void getMessages() {
FirebaseDatabase.getInstance().getReference().child(pathtomsgs).addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
Log.e("childrenCount", String.valueOf(+dataSnapshot.getChildrenCount()));
mTotalChildren = dataSnapshot.getChildrenCount();
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
Query messageQuery = FirebaseDatabase.getInstance().getReference().child(pathtomsgs).limitToLast(20);
childEventListenerMain = new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
loading = true;
MessageModel messageModel = dataSnapshot.getValue(MessageModel.class);
if (messageModel != null) {
messageModel.chat_id = chat_id;
messageModel.message_id = dataSnapshot.getKey();
messageArrayList.add(messageModel);
messageAdapter.notifyDataSetChanged();
mLastKey = messageArrayList.get(0).message_id;
rvMessages.scrollToPosition(messageArrayList.size() - 1);
}
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(mContext, "Problem loading more images...", Toast.LENGTH_LONG).show();
}
};
messageQuery.addChildEventListener(childEventListenerMain);
ValueEventListener messageChildSINGLEValueEventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
pb_messages.setVisibility(View.GONE);
System.out.println("We're done loading messages " + dataSnapshot.getChildrenCount() + " items");
loading = false;
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
messageQuery.addListenerForSingleValueEvent(messageChildSINGLEValueEventListener);
}
public void getMoreMessages() {
tempMessageArrayList.clear();
Query messageQuery = FirebaseDatabase.getInstance().getReference().child(pathtomsgs).orderByKey().endAt(mLastKey).limitToLast(20);
childEventListenerPager = new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
loading = true;
MessageModel messageModel = dataSnapshot.getValue(MessageModel.class);
if (messageModel != null) {
messageModel.chat_id = chat_id;
messageModel.message_id = dataSnapshot.getKey();
tempMessageArrayList.add(messageModel);
}
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(mContext, "Problem loading more images...", Toast.LENGTH_LONG).show();
}
};
messageQuery.addChildEventListener(childEventListenerPager);
ValueEventListener messageChildSINGLEValueEventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
System.out.println("We're done loading messages " + dataSnapshot.getChildrenCount() + " items");
tempMessageArrayList.remove(tempMessageArrayList.size() - 1);
messageArrayList.addAll(0, tempMessageArrayList);
mLastKey = messageArrayList.get(0).message_id;
messageAdapter.notifyDataSetChanged();
//rvMessages.scrollToPosition(20);
layoutManager.scrollToPositionWithOffset(19, 0);
loading = false;
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
messageQuery.addListenerForSingleValueEvent(messageChildSINGLEValueEventListener);
}
@Override
protected void onDestroy() {
FirebaseDatabase.getInstance().getReference().child(pathtomsgs).removeEventListener(childEventListenerPager);
FirebaseDatabase.getInstance().getReference().child(pathtomsgs).removeEventListener(childEventListenerMain);
super.onDestroy();
}
}
क्या आपको पेजिंग करने के लिए दूर मिला है? – Raghunandan
क्या आपको अंकन के लिए कुछ मिला? मुझे फायरबेस का उपयोग करके अपने आवेदन में पेजिनेशन को भी लागू करने की आवश्यकता है। –