即使手机屏幕关闭，如何保持GPS和插座连接打开？

Question

Problem: I have to periodically send the GPS data to a server.

Approach: I have used alarm manager which runs a background service. It acquires GPS data and sends it over the socket. It works fine until the screen is on.

Issue: However, when screen turns off, no data is received on the server. But as soon as I turn the screen on, the server receives all the data at once.

Already tried: I have already tried wakelock but still facing the same problem.

Please help me in resolving this issue.

Thanks in advance.

public class service_task extends Service {

    public static int PORT = 6789;
    public static String IP = "192.168.20.16";
    public PowerManager.WakeLock wl;

    @SuppressLint({"MissingPermission", "InvalidWakeLockTag"})
    @Override
    public void onCreate() {
        PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
        wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyApp::service_task");
        wl.setReferenceCounted(true);
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }


    private class ServerThread extends Thread implements LocationListener {

        public LocationManager locationManager = null;
        public String msg = "default";
        public String id = "default";
        private Location mLocation = null;
        public Socket socket = null;
        public int serviceid;
        public LocationListener LL;


        public ServerThread(LocationManager locationManager, String id, int serviceid) {
            super("UploaderService-Uploader");
            this.locationManager = locationManager;
            this.id=id;
            this.serviceid=serviceid;
            LL=this;
        }

        @SuppressLint("MissingPermission")
        public void run() {

            wl.acquire();
            Looper.prepare();
            Log.d("func", "Looper");
            this.locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
            Handler handler=new Handler(Looper.myLooper());
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    Log.d("func", "no GPS data found");
                    locationManager.removeUpdates(LL);
                    Looper.myLooper().quit();
                }
            };
            handler.postDelayed(runnable, 30000);
            Looper.loop();

            Calendar calendar = Calendar.getInstance();
            SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
            String cal = sdf.format(calendar.getTime());

            if (mLocation!=null) {
                msg = id + "    time:" + cal + "    GPS data:" + mLocation;
            }else{
                msg = id + "    time:" + cal + "    No GPS data";
            }
            Log.d("D", msg);
            socket = null;
            SocketAddress address = new InetSocketAddress(IP, PORT);
            socket = new Socket();
            try {
                Log.d("D", "server connected");
                socket.connect(address, 3000);
            } catch (IOException e) {
                Log.d("D","server not connected");
                e.printStackTrace();
            }
            try {
                socket.setSoTimeout(3000);
            } catch (SocketException e) {
                Log.d("socket timeout","server took too long to respond");
                //e.printStackTrace();
            }

            OutputStream out = null;
            try {
                out = socket.getOutputStream();
            } catch (IOException e) {
                e.printStackTrace();
            }
            PrintWriter output = new PrintWriter(out);
            output.print(msg);
            output.flush();
            output.close();
            try {
                socket.close();
                Log.d("D", "server disconnected for "+id);
            } catch (IOException e) {
                e.printStackTrace();
            }
            Log.d("D", "Stopped for "+id);

            wl.release();
            stopSelf(serviceid);
        }

        @Override
        public void onLocationChanged(Location location) {
            Log.d("func", "location changed");
            mLocation = location;
            this.locationManager.removeUpdates(this);
            Looper.myLooper().quit();
        }

        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {

        }

        @Override
        public void onProviderEnabled(String s) {

        }

        @Override
        public void onProviderDisabled(String s) {

        }

    }

    @SuppressLint("MissingPermission")
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Date currentTime = Calendar.getInstance().getTime();
        IP= intent.getStringExtra("IP");
        PORT= Integer.parseInt(intent.getStringExtra("port"));
        String id= intent.getStringExtra("ID");
        Log.d("func", currentTime+" Started for "+id);
        LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

        ServerThread thread = new ServerThread(locationManager, id, startId);
        thread.start();
        return START_STICKY;
    }
}

Answer 1

When mobile screen is off and if there are no wakelocks pending in device, device CPU will be off, and If device goes to doze mode, there will be further restrictions in device. And with the Android latest versions there are restrictions on App background behavior and location updates. And in the code, you are using deprecated version of Location updates approach. So the behavior you reported is expected.

There is a google code labs tutorial on location updates, suggesting the correct approach to be followed to receive location updates consistently, please follow that https://codelabs.developers.google.com/codelabs/background-location-updates-android-o