android列表只从一个空白刷新，而不是从另一个空白

Question

这对我来说很奇怪：在我的项目中（顺便说一句，它是从Yaxim派生的，所以它是一个android聊天应用程序），我试图通过messageeventlistener实现写通知。我确实收到了通知事件。为了让它出现在listview（在另一个类中）中，我在数据库中添加了一行，就好像它是一条消息一样（只有文本是"…"）。我添加了一个计数器，该行被正确地插入到数据库中（随后，当实际消息到来时，该行会从数据库中删除）。notifychanges也被正确调用。奇怪的是，尽管如此，该行并没有出现在列表视图中。如果我把这个过程移到下面几行，在常规消息的packetlistener上，它就会被插入。然而，我不能这样做，因为packetlistener并没有正确地接收到所有组成通知，所以它并不能一直用于此目的。此外，当写入通知正确插入数据库时，如果我将过程保留在messageEventNotificationListener（）中，则当实际消息到达时，写入通知消息不会被删除（并且iCount不断增加）；如果我把过程放在packetListener中，它会这样做（因此，在消息被推送到数据库后，iCount等于0）

这是messageeventlistener:

private void messageEventNotificationListener(){
    // Create a MessageEventManager
    if (mMessageEventManager == null)
        mMessageEventManager = new MessageEventManager(mXMPPConnection);
      // Add the listener that will react to the event notifications
    mMessageEventManager.addMessageEventNotificationListener(new MessageEventNotificationListener() {
          public void deliveredNotification(String from, String packetID) {
              Log.d(TAG, "The message has been delivered (" + from + ", " + packetID + ")");
          }
          public void displayedNotification(String from, String packetID) {
              Log.d(TAG, "The message has been displayed (" + from + ", " + packetID + ")");
          }
          public void composingNotification(String from, String packetID) {
              Log.d(TAG, "The message's receiver is composing a reply (" + from + ", " + packetID + ")");
              //controlla se l'utente non sta già scrivendo 
              String selection = ChatConstants.JID + " = '" + from + "' AND " +
                        ChatConstants.DELIVERY_STATUS + " = " + ChatConstants.DS_WRITING;
                Cursor cursor = mContentResolver.query(ChatProvider.CONTENT_URI,
                            new String[] { "count(" + ChatConstants._ID + ")" },
                            selection, null, null);
                cursor.moveToFirst();
                int iCount = cursor.getInt(0);
                //if (iCount == 0)
                //{
                    addChatMessageToDB(ChatConstants.INCOMING, from, "...", ChatConstants.DS_WRITING, System.currentTimeMillis(), packetID);
                //}
          }
          public void offlineNotification(String from, String packetID) {
              Log.d(TAG, "The message's receiver is offline (" + from + ", " + packetID + ")");
          }
          public void cancelledNotification(String from, String packetID) {
              Log.d(TAG, "The message's receiver cancelled composing a reply (" + from + ", " + packetID + ")");

          }
      });   
}

这是数据包记录器：

private void registerMessageListener() {
    // do not register multiple packet listeners
    if (mPacketListener != null)
        mXMPPConnection.removePacketListener(mPacketListener);
    PacketTypeFilter filter = new PacketTypeFilter(Message.class);
    mPacketListener = new PacketListener() {
        public void processPacket(Packet packet) {
            try {
            if (packet instanceof Message) {
                Message msg = (Message) packet;
                String chatMessage = msg.getBody();
                DeliveryReceipt dr = (DeliveryReceipt)msg.getExtension("received", DeliveryReceipt.NAMESPACE);
                if (dr != null) {
                    Log.d(TAG, "got delivery receipt for " + dr.getId());
                    changeMessageDeliveryStatus(dr.getId(), ChatConstants.DS_DELIVERED);
                }

                if (chatMessage == null)
                    return;
                if (msg.getType() == Message.Type.error) {
                    chatMessage = "<Error> " + chatMessage;
                }
                long ts;
                DelayInfo timestamp = (DelayInfo)msg.getExtension("delay", "urn:xmpp:delay");
                if (timestamp == null)
                    timestamp = (DelayInfo)msg.getExtension("x", "jabber:x:delay");
                if (timestamp != null)
                    ts = timestamp.getStamp().getTime();
                else
                    ts = System.currentTimeMillis();
                String fromJID = getJabberID(msg.getFrom());
                //elimina il messaggio "writing" se esiste
                     deleteWritingChatMessageFromDB(fromJID);
                    if (msg.getExtension("request", DeliveryReceipt.NAMESPACE) != null) {
                        // got XEP-0184 request, send receipt
                        sendReceipt(msg.getFrom(), msg.getPacketID());
                    }
                    addChatMessageToDB(ChatConstants.INCOMING, fromJID, chatMessage, ChatConstants.DS_NEW, ts, msg.getPacketID());
                    mServiceCallBack.newMessage(fromJID, chatMessage);
                }
            }
            } catch (Exception e) {
                // SMACK silently discards exceptions dropped from processPacket :(
                Log.e(TAG, "failed to process packet:");
                e.printStackTrace();
            }
    };
    mXMPPConnection.addPacketListener(mPacketListener, filter);
}

最后是插入和删除方法

private void addChatMessageToDB(int direction, String JID,
        String message, int delivery_status, long ts, String packetID) {
    ContentValues values = new ContentValues();
    values.put(ChatConstants.DIRECTION, direction);
    values.put(ChatConstants.JID, JID);
    values.put(ChatConstants.MESSAGE, message);
    values.put(ChatConstants.DELIVERY_STATUS, delivery_status);
    values.put(ChatConstants.DATE, ts);
    values.put(ChatConstants.PACKET_ID, packetID);
    Uri noteUri = mContentResolver.insert(ChatProvider.CONTENT_URI, values);
    //mContentResolver.notifyChange(noteUri, null);
}
private void deleteWritingChatMessageFromDB(String JID) {
    int count = mContentResolver.delete(ChatProvider.CONTENT_URI,
            ChatConstants.JID + " = ? AND " + ChatConstants.MESSAGE + " = ? AND " + ChatConstants.DELIVERY_STATUS + " = ?", new String[] { JID, "...", "3" });
    debugLog("deleteWritingChatMessageEntryFromDB: Deleted " + count + " entries");
}

这两个方法都被调用到ChatProvider类中，并以getContext（）.getContentResolver（）.notifyChange（url，null）；

Answer 1

发现问题不同：我发布这篇文章只是为了防止其他人遇到同样的问题。消息实际上是插入到数据库中的，但虽然packetlistener只返回jid，但messageeventlistener也返回jid和末尾的资源，这些资源需要在插入之前删除。完成后，消息出现在列表中。此外：我发布的代码不完全正确，无法处理messageEvent。需要直接从packetListener内部调用侦听器。