我正在尝试创建聊天。然而，我面临着一个大问题。当我从聊天 recyclerView 中删除条目时，该条目保留在那里，但会按预期从 firebase 数据库中删除(我的意思是只有从数据库中删除才有效)。仅当我关闭 Activity 并再次打开它时，它才会消失。我的 recyclerView 具有每次用户滚动时加载 10 个以上条目的功能。
我不明白如何从 recyclerView 中删除该条目？
我需要调用函数loadMoreMessages()吗？刷新 Activity ？
MessageAdapter.java
public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageViewHolder>{
public class MessageViewHolder extends RecyclerView.ViewHolder {
public TextView messageText, displayName;
public CircleImageView profileImage;
public ImageView messageImage;
public MessageViewHolder(View itemView) {
super(itemView);
messageText = (TextView) itemView.findViewById(R.id.message_text_layout);
profileImage = (CircleImageView) itemView.findViewById(R.id.message_profile_layout);
displayName = (TextView) itemView.findViewById(R.id.name_text_layout);
messageImage = (ImageView) itemView.findViewById(R.id.message_image_layout);
}
}
private List<Messages> mMessageList;
private FirebaseAuth mAuth;
private DatabaseReference mUserDatabase;
private DatabaseReference mUserDatabaseSettings;
private String rul, fromUser_t;
private UserAccountSettings mUserAccountSettings;
public MessageAdapter(List<Messages> mMessageList) {
this.mMessageList = mMessageList;
}
@Override
public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.message_single_layout,parent,false);
mAuth = FirebaseAuth.getInstance();
return new MessageViewHolder(v);
}
@Override
public void onBindViewHolder(final MessageViewHolder holder, final int position) {
final String current_user_id = mAuth.getCurrentUser().getUid();
final Messages c = mMessageList.get(position);
final String from_user = c.getFrom();
final String message_type = c.getType();
final String messageContent = c.getMessage();
/**
* popup for text message
*/
// check if the message is from the current user
if(from_user.equals(current_user_id))
{
holder.messageText.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//popup menu to select option
CharSequence options[] = new CharSequence[]
{
"Delete from my phone",
"Delete for Everyone" ,
"Cancel"
};
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());
builder.setTitle("Message Options");
builder.setItems(options, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//Click Event for each item.
if(i == 0)
{
deleteSentMessage(position, holder);
// Intent intent = new Intent(holder.itemView.getContext(), ChatActivity.class);
// holder.itemView.getContext().startActivity(intent);
//MessageViewHolder.class.notify();
holder.messageText.setPaintFlags(holder.messageText.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
}
else if(i == 1)
{
deleteMessageForEveryOne(position, holder);
// Intent intent = new Intent(holder.itemView.getContext(), ChatActivity.class);
// holder.itemView.getContext().startActivity(intent);
//notifyDataSetChanged();
//holder.messageText.setVisibility(View.GONE);
}
}
});
builder.show();
}
});
}else
{
// similar code to check if the message is from the other user
}
holder.messageText.setVisibility(View.GONE);
holder.messageImage.setVisibility(View.GONE);
if("text".equals(message_type))
{
holder.messageText.setVisibility(View.VISIBLE);
if(from_user.equals(current_user_id))
{
holder.messageText.setBackgroundResource(R.drawable.message_text_background);
holder.messageText.setTextColor(Color.WHITE);
//todo left right not working
holder.messageText.setGravity(Gravity.LEFT);
}else
{
holder.messageText.setBackgroundColor(Color.WHITE);
holder.messageText.setTextColor(Color.BLACK);
holder.messageText.setGravity(Gravity.RIGHT);
}
holder.messageText.setText(c.getMessage());
}else
{
holder.messageImage.setVisibility(View.VISIBLE);
UniversalImageLoader.setImage(messageContent,holder.messageImage,null,"");
}
}
@Override
public int getItemCount() {
return mMessageList.size();
}
/**
function to Delete from my phone
**/
private void deleteSentMessage(final int position, final MessageViewHolder holder)
{
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
function to Delete from receiver phone
**/
private void deleteReceiveMessage(final int position, final MessageViewHolder holder)
{
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
function to Delete from both sides
**/
private void deleteMessageForEveryOne(final int position, final MessageViewHolder holder)
{
final DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
rootRef.child("messages")
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}
}
});
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
}
ChatActivity.java
public class ChatActivity extends AppCompatActivity {
private static final String TAG = "ChatActivity";
//todo check is user is logedin
//user with whom Iam talking to
private String mChatUser;
private Toolbar mChatToolbar;
private DatabaseReference mRootRef;
private TextView mTitleView, mLastSeenView;
private CircleImageView mProfileImage;
private FirebaseAuth mAuth;
private String mCurrentUserId;
private ImageButton mChatAddBtn;
private ImageButton mChatSendBtn;
private EditText mChatMessageView;
private RecyclerView mMessagesList;
private SwipeRefreshLayout mRefreshLayout;
private final List<Messages> messagesList = new ArrayList<>();
private LinearLayoutManager mLinearLayout;
private MessageAdapter mAdapter;
private static final int TOTAL_ITEMS_TO_LOAD = 10;
private int mCurrentPage = 1;
private int itemPos =0;
private String mLastKey = "";
private String mPrevKey = "";
private static final int GALLERY_PICK = 1;
//Storage Firebase
private StorageReference mImageStorage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
// create a toolbar and set the title as the user with we are chatting to
mChatToolbar = (Toolbar) findViewById(R.id.chat_app_bar);
setSupportActionBar(mChatToolbar);
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
// to add a custom view to the toolbar
actionBar.setDisplayShowCustomEnabled(true);
mRootRef = FirebaseDatabase.getInstance().getReference();
mAuth = FirebaseAuth.getInstance();
mCurrentUserId = mAuth.getCurrentUser().getUid();
mChatUser = getIntent().getStringExtra("user_id");
String userName = getIntent().getStringExtra("user_name");
getSupportActionBar().setTitle(userName);
// String userName = getIntent().getStringExtra("user_name");
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View action_bar_view = inflater.inflate(R.layout.chat_custom_bar, null);
actionBar.setCustomView(action_bar_view);
// ---------- Custom Action bar items ---
mTitleView = (TextView) findViewById(R.id.custom_bar_title);
mLastSeenView = (TextView) findViewById(R.id.custom_bar_seen);
mProfileImage = (CircleImageView) findViewById(R.id.custom_bar_image);
mChatAddBtn = (ImageButton) findViewById(R.id.chat_add_btn);
mChatSendBtn = (ImageButton) findViewById(R.id.chat_send_btn);
mChatMessageView = (EditText) findViewById(R.id.chat_message_view);
mAdapter = new MessageAdapter(messagesList);
mImageStorage= FirebaseStorage.getInstance().getReference();
mMessagesList = (RecyclerView) findViewById(R.id.messages_list);
mRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.message_swipe_layout);
mLinearLayout = new LinearLayoutManager(this);
mMessagesList.setHasFixedSize(true);
mMessagesList.setLayoutManager(mLinearLayout);
//mMessagesList.setItemViewCacheSize(25);
mMessagesList.setDrawingCacheEnabled(true);
mMessagesList.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
mMessagesList.setAdapter(mAdapter);
loadMessages();
mTitleView.setText(userName);
mRootRef.child("users").child(mChatUser).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String online = dataSnapshot.child("lastSeen").getValue().toString();
//String image = dataSnapshot.child()
if(online.equals("true")){
mLastSeenView.setText("Online");
}else {
GetTimeAgo getTimeAgo = new GetTimeAgo();
long lastTime = Long.parseLong(online);
String lastSeenTime = getTimeAgo.getTimeAgo(lastTime, getApplicationContext());
mLastSeenView.setText(lastSeenTime);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
mRootRef.child("Chat").child(mCurrentUserId).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if(!dataSnapshot.hasChild(mChatUser)){
Map chatAddMap = new HashMap();
chatAddMap.put("seen", false);
chatAddMap.put("timestamp", ServerValue.TIMESTAMP);
Map chatUserMap = new HashMap();
chatUserMap.put("Chat/" + mCurrentUserId + "/" + mChatUser, chatAddMap); //add map to current user
chatUserMap.put("Chat/" + mChatUser + "/" + mCurrentUserId, chatAddMap);
mRootRef.updateChildren(chatUserMap, new DatabaseReference.CompletionListener() {
@Override
public void onComplete(@Nullable DatabaseError databaseError, @NonNull DatabaseReference databaseReference) {
if(databaseError != null){
//Log.d(TAG, "onComplete: CHAT LOG", databaseError.getMessage());
Log.e(TAG, "onComplete: CHAT_LOG" + databaseError.getMessage().toString());
}
}
});
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
mChatSendBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sendMessage();
}
});
// open gallery to get an image
mChatAddBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent galleryIntent = new Intent();
galleryIntent.setType("image/*");
galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(galleryIntent,"SELECT IMAGE"), GALLERY_PICK);
}
});
//pagination
mRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
mCurrentPage++;
// each time it loads a new page should go to position zero
itemPos = 0;
loadMoreMessages();
}
});
}
/**
* load more messages everytime uesr refreshes
*/
private void loadMoreMessages() {
DatabaseReference messageRef = mRootRef.child("messages").child(mCurrentUserId).child(mChatUser);
Query messageQuery = messageRef.orderByKey().endAt(mLastKey).limitToLast(10);
messageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages message = dataSnapshot.getValue(Messages.class);
String messageKey = dataSnapshot.getKey();
if(!mPrevKey.equals(messageKey)){
messagesList.add(itemPos++, message);
Log.d(TAG, "onChildAdded: xx" + mPrevKey + "---" + mLastKey);
} else {
mPrevKey = mLastKey;
}
if(itemPos == 1){
mLastKey = messageKey;
}
Log.d(TAG, "onChildAdded: TOTALKEUS" + "lastkey: " + mLastKey + " | Prev key : " + mPrevKey + " | Message Key : " + messageKey);
mAdapter.notifyDataSetChanged();
mRefreshLayout.setRefreshing(false);
mLinearLayout.scrollToPositionWithOffset(itemPos , 0);
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
/**
* method used to load messages once
*/
private void loadMessages() {
//query to get pagination and last 10 messages
DatabaseReference messageRef = mRootRef.child("messages").child(mCurrentUserId).child(mChatUser);
Query messageQuery = messageRef.limitToLast(mCurrentPage * TOTAL_ITEMS_TO_LOAD);
messageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages message = dataSnapshot.getValue(Messages.class);
itemPos++;
if(itemPos == 1){
// get the key to be user as a start point when loading more items
String messageKey = dataSnapshot.getKey();
mLastKey = messageKey;
mPrevKey = messageKey;
Log.d(TAG, "onChildAdded: last " +mLastKey + " prev " + mPrevKey + " messa " + messageKey + "-----------");
}
messagesList.add(message);
mAdapter.notifyDataSetChanged();
//pagination - define the bottom of the recycler view
//automatic scroll to bottom
mMessagesList.scrollToPosition(messagesList.size() - 1);
mRefreshLayout.setRefreshing(false);
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
/**
* send photo message
* @param requestCode
* @param resultCode
* @param data
*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == GALLERY_PICK && resultCode == RESULT_OK){
Uri imageUri = data.getData();
final String current_user_ref = "messages/" + mCurrentUserId + "/" + mChatUser;
final String chat_user_ref = "messages/" + mChatUser + "/" + mCurrentUserId;
DatabaseReference user_message_push = mRootRef.child("messages")
.child(mCurrentUserId).child(mChatUser).push();
final String push_id = user_message_push.getKey();
StorageReference filepath = mImageStorage.child("message_images").child( push_id + ".jpg");
filepath.putFile(imageUri).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
@Override
public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task) {
if(task.isSuccessful()){
Task<Uri> result = task.getResult().getMetadata().getReference().getDownloadUrl();
result.addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
String download_url = uri.toString();
Map messageMap = new HashMap();
messageMap.put("message", download_url);
messageMap.put("seen", false);
messageMap.put("type", "image");
messageMap.put("time", ServerValue.TIMESTAMP);
messageMap.put("from", mCurrentUserId);
messageMap.put("to", mChatUser);
messageMap.put("messageID", push_id );
Map messageUserMap = new HashMap();
messageUserMap.put(current_user_ref + "/" + push_id, messageMap);
messageUserMap.put(chat_user_ref + "/" + push_id, messageMap);
mChatMessageView.setText("");
mRootRef.updateChildren(messageUserMap, new DatabaseReference.CompletionListener() {
@Override
public void onComplete(DatabaseError databaseError, DatabaseReference databaseReference) {
if(databaseError != null){
Log.d("CHAT_LOG", databaseError.getMessage().toString());
}
}
});
}
});
}
}
});
}
}
}
``
最佳答案
您正在使用ChildEventListener在你的messageQuery ，它有以下主要方法:
-
onChildAdded，最初为每个与messageQuery匹配的子节点调用它查询，随后当任何子节点添加到落入messageQuery的数据库中时. -
onChildRemoved，当从数据库中删除任何(掉落的)子节点(或至少删除messageQuery正在监听的部分)时，会调用该函数。 -
onChildChanged，当任何子节点messageQuery时调用它is Listening 已在数据库中修改。
如果我看看你的实现，你只实现了 onChildAdded 。因此，当您从数据库中删除子节点时，Firebase 会告诉您 ChildEventListener关于它，但那什么也没做。
要在消息从数据库中删除时从 UI 中删除该消息，您需要实现:
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
// TODO: remove the message matching dataSnapshot from messagesList
// TODO: call adapter.notifyDataSetChanged() so that the UI gets updates
}
关于java - 如何从 RecyclerView 中实时删除条目，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56436092/