Update android Textview continuously

问题

I am working on an Android Application which have an one activity class and service class. In service, Continuous bulk data (1090 bytes) will be received every 10 milliseconds. I need to update the text view continuously with these bulk data. What is recommended way to update Text view from a continuous background service?

Service Class

public class RecepService extends Service {

public static Handler mHandler;
StringBuilder hexstring;

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate() {
    super.onCreate();

    init();
}

private void init() {

    mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 0x123) {

                byte[] readBuf = (byte[]) msg.obj;
                int readBuflen = msg.arg1;

                // here will receive 1090 bytes of data 
                // every 10 milliseconds
                Receivepatientattributes(readBuf,readBuflen);
            }
        }
    };
}

public void Receivepatientattributes(byte[] readBuf, int len) {

    String total_data = "";
    total_data = bytetohex(readBuf, len);
    MainActivity.recep.setText(MainActivity.recep.getText().toString() + "\t" +
            "" + total_data );
}

String bytetohex(byte[] txt, int len) {

    String p="";
    byte[] text = new byte[len];
    text = txt;

    hexstring = new StringBuilder();
    for (int j = 0; j < len; j++) {

        String hex= Integer.toHexString(0xFF & txt[j]);

        if (hex.length()==1) {
            hexstring.append("0");
        }

        hexstring.append(hex+" ");

    }

    p=p+hexstring.toString();
    return p;
}

@Override
public void onDestroy() {
    super.onDestroy();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    return START_STICKY;
}
}

回答1:

If you want to use Schedule and timer task then you can See My Answer

To solve current issue follow this bellow instructions. Suppose your activity has a Broadcast Receiver

private BroadcastReceiver mReceiver;

Then you override methods onResume() where your broadcast receiver will be registered and also onPause() where will your receiver be unregistered:

@Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();

        IntentFilter intentFilter = new IntentFilter(
                "android.intent.action.MAIN");

        mReceiver = new BroadcastReceiver() {

            @Override
            public void onReceive(Context context, Intent intent) {
                //extract your message from intent
                String msg_for_me = intent.getStringExtra("YOUR_MESSAGE");
                //log your message value
                Log.i("MyTag", msg_for_me);

            }
        };
        //registering your receiver
        this.registerReceiver(mReceiver, intentFilter);
    }

    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        //unregister your receiver
        this.unregisterReceiver(this.mReceiver);
    }

Here the broadcast receiver is filtered via android.intent.action.MAIN and from Service the message will BroadCast using this filter

Now your Method Receivepatientattributes will like this :

public void Receivepatientattributes(byte[] readBuf, int len) {

    String total_data = "";
    total_data = bytetohex(readBuf, len);

    Intent i = new Intent("android.intent.action.MAIN").putExtra("YOUR_MESSAGE",  total_data);
    this.sendBroadcast(i);

}

Thats it. :)

回答2:

User LocalBroadcastManager

public void Receivepatientattributes(byte[] readBuf, int len) {
    String total_data = "";
    total_data = bytetohex(readBuf, len);

    Intent intent = new Intent("update-text");
    // add data
    intent.putExtra("message", total_data);
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

In MainActivity

@Override
public void onResume() {
  super.onResume();

  // Register mMessageReceiver to receive messages.
  LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
      new IntentFilter("update-text"));
}

private boolean mCanBeUpdated = true;
private static final int ONE_SEC = 1000; //ms
private static final int RECEPTION_SPEED = 10; //ms
private static final int CYCLES = (int) (ONE_SEC / RECEPTION_SPEED);
private int mCurrentCycle = -1;
private String mMsgCache = "";

// handler for received Intents for the "update-text" event 
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // Extract data included in the Intent
        String message = intent.getStringExtra("message");
        Log.d("receiver", "Got message: " + message);

        mMsgCache = mMsgCache + "\t" + message;

        if (mCanBeUpdated) {
            // No problem updating UI here, refer --> http://stackoverflow.com/a/5676888/1008278
            final Handler handler = new Handler(context.getMainLooper());
            handler.post(new Runnable() {
                @Override
                public void run() {
                    MainActivity.recep.append(mMsgCache);
                    mMsgCache = "";
                }
            });

            mCanBeUpdated = false;
        } else if (mCurrentCycle >= CYCLES) {
            mCurrentCycle = -1;
            mCanBeUpdated = true;
        } else {
            mCurrentCycle++;
        }
    }
};

@Override
protected void onPause() {
  // Unregister since the activity is not visible
  LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
  super.onPause();
} 

Reference

回答3:

You can use Timer for Continously updating your textview.

Set value in preferences every time when your service is running with the latest value.

Now in Timer get that value from preferences and update your TextView with that value.

Here is some code :

class UpdateTimeTask extends TimerTask {
   public void run() {

   textview.setText("updated value");
   }
}

Set in onCreate ();

    Timer timer = new Timer();
    UpdateTimeTask  UpdateTimeTask = new UpdateTimeTask ();
    timer.schedule(UpdateTimeTask, 1000);

来源：https://stackoverflow.com/questions/33448287/update-android-textview-continuously