Question

我正在开发一个Android项目，我正在尝试集成Cometd框架提供的PUSH服务。现在，每当有Conversation的新邮件到达时，我想通知ChatMessagesActivity，其中包含两个用户之间的邮件列表。

现在，当其他用户向Android应用发送消息时，我想更新用户的视图。我尝试通过调用notifyDataSetHasChanged()上的adapter来做到这一点，但因为我在View线程之外调用它，我收到错误。

该方法是静态的，因为在Conversation类中接收新消息，而消息在ChatMessagesActivity类中进行。对于两个类之间的通信，我创建了2个静态方法，它们就像发送和发送的双向桥。接收消息。

我希望我很清楚，如果有任何疑问，请告诉我。

ChatMessagesActivity.java：

public class ChatMessagesActivity extends ApplicationDrawerLoader {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chat_messages);

        chatList = (ListView)findViewById(R.id.chatList);

 new getPrivateChatsForUser(this).execute();

}

// IN the method below, I receive information from another activity.

    public static void recieveUpdatedMessage(String channelName, Map<String, Object> input){
 Boolean found = Arrays.asList(channelName.split(" ")).contains("chat");
        if(found){
            int processedChannelName = Integer.valueOf(channelName.replace("/chat/",""));
            if(processedChannelName == groupAccountId){

// Here i tried calling adapter.NotifyDataSetchanged();.. Didn't fly.

            }
        }
}

// Async method retrieving messages.
    public class getPrivateChatsForUser extends AsyncTask<Void, Void, ResponseEntity<RestReplies[]>> {

        ChatMessagesActivity chatMessagesActivity = null;

        getPrivateChatsForUser(ChatMessagesActivity chatMessagesActivity) {
            this.chatMessagesActivity = chatMessagesActivity;
        }
 @Override
        protected ResponseEntity<RestReplies[]> doInBackground(Void... params) { 
// network connection related stuff, not relevant to problem
}
 @Override
        protected void onPostExecute(ResponseEntity<RestReplies[]> responseEntity) {
            super.onPostExecute(responseEntity);
            RestReplies[] restRepliesArray = responseEntity.getBody();
            Collections.addAll(restRepliesList, restRepliesArray);

            ArrayList<HashMap<String, String>> chatMessagesHashMapList = new ArrayList<HashMap<String, String>>();

            for (RestReplies restReplies : restRepliesList) {
                HashMap<String, String> chatMap = new HashMap<>();
                chatMap.put(chatText, restReplies.getReplyText());
                chatMap.put(firstName, restReplies.getReplyingPersonName());
                chatMap.put(chatImage, restReplies.getSenderImage());
                chatMap.put(privateChannel,"/service/person/"+String.valueOf(conversationId));
                chatMessagesHashMapList.add(chatMap);
            }

            chatList = (ListView) findViewById(R.id.chatList);

            chatMessagesAdapter = new ChatMessagesAdapter(chatMessagesActivity, chatMessagesHashMapList);

            chatList.setAdapter(chatMessagesAdapter);

            chatList.scrollTo(0, chatList.getHeight());

        }
    }

那么，我应该如何指示数据集已被更改。以及适配器如何知道在何处以及如何获取已更改的数据集。任何人都可以帮我解决这个问题。非常感谢......： - ）

Answer 1

在适配器上使用广播接收器，并在推送服务中使用Android LocalBroadcast发送本地广播

private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent)
    {

        if(intent.getAction().equals("MYREFRESH"))
        {
            notifiyDataSetChanged();
        }
    }
};

在适配器中的构造函数中注册此接收器

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("MYREFRESH");
LocalBroadcastManager.getInstance(context).registerReceiver(broadReceiver, intentFilter);

如果您获得了推送通知，那么在您的推送中

Intent intent = new Intent();
intent.putExtra(...) //send any data to your adapter
Intent.setAction("myaction");
LocalBroadcastManager.getInstance(context).sendBroadcast(intent);

Answer 2

处理此问题的方法是使用广播或总线模式。您可以使用一些好的总线库，例如http://square.github.io/otto/或LocalBroadcast

我过去的回答显示了如何使用LocalBroadcast系统：Refreshing fragments in FragmentActivity after sync service runs

Android：通知适配器数据集已从静态方法更改

2 个答案: