在活动打开时接收到广播时更新活动/触发事件

Question

我已经制作了一个广播接收器，它会在从服务器收到消息时发出通知。 当我点击通知时，它会打开预期的活动并更新消息列表。

我的问题是如何在活动打开时收到广播时更新消息列表（触发事件）？ （就像他们在“WhatsApp”中所做的那样，他们不会在聊天时发送通知，而是更新消息列表）。

我的广播接收器如下：

public class NotifReceiver extends BroadcastReceiver {
    private Context context;
    private String notifTitle,notifStatus;
    public static int NOTIF_ID = 54321;

    @Override
    public void onReceive(Context context, Intent intent) {
        this.context = context;

         if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {
            context.startService(new Intent(context, NotifService.class));
            Log.i("Aditya", "Background Service of SamajApp Started");
         }
        if(intent.getAction().equals("Aditya.Notification")){
            showNotif();
        }
    }

    public void showNotif(){
        NotificationManager notifManager = NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);

        Intent i = new Intent(context, MainActivity.class);
        i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        PendingIntent pIntent = PendingIntent.getActivity(context, 0, i, 0);

        Uri soundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

        NotificationCompat.Builder notif = new NotificationCompat.Builder(context);
        notif.setContentTitle("SamajApp");
        notif.setContentText(notifTitle);
        notif.setSmallIcon(R.drawable.logo);
        notif.setSound(soundUri);
        notif.setContentIntent(pIntent);
        notifManager.notify(NOTIF_ID, notif.build());
    }
}

我已经在清单中注册了它，它运行良好。

我的MainActivity如下：

 public class MainActivity extends Activity {
       private ListView mListView;

       @Override
        protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main); 
             mListView = (ListView) findViewById(R.id.listViewHome);

             updateList();

        }

        //MsgListAdapter is my custom Adapter to populate Listview,
        private void updateList(){
        registerForContextMenu(mListView);
        Vector<HashMap<String, String>> list = getMsgListfromDB();  //gets message list from database
        Vector<HashMap<String, byte[]>> blobList = getBlobListfromDB();  //gets blob list from db.
        ad = new MsgListAdapter(getApplicationContext(), list,blobList,R.layout.listrow,
                new String[] { "MsgCat", "MsgDt_Simp","by","FlagUnread"},
                new int[] {R.id.textViewCat, R.id.textViewDateTime,R.id.textViewBy},
                new int[] {R.id.imageViewMsgImg,R.id.imageViewCatImg},R.id.imageViewUnreaddr);
        mListView.setAdapter(ad);
            }
       }

对此的任何帮助将不胜感激。 谢谢。

Answer 1

两种方式，

1. 要么在您的 Activity 中有一个静态 Handler 声明，并使用相同的 post 一条消息返回到 Activity，如果还活着则更新您需要的任何内容。

喜欢：

public Handler MyHandler= new Handler() {
    public void handleMessage(android.os.Message msg) {
        // Update your UI
    }

};

1. 将广播接收器声明为 Activity 类中的静态子类，这样一旦收到后续广播，您就可以轻松更新 UI。

喜欢：

public class MainActivity extends Activity {


    private MyReceiver mReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }



    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        IntentFilter mFilter = new IntentFilter();
        // add action to this filters

        // Initialize ur receiver
        mReceiver = new MyReceiver();
        // register when activity is resumed
        registerReceiver(mReceiver, mFilter);
    }

    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        // unregister when activity is paused
        if(mReceiver != null){
            unregisterReceiver(mReceiver);
        }
    }



    class MyReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            // This is ur receiver do whatever you want here wIth UI

        }

    }

在我看来，第二个会更容易使用。