How to rescue the GPS location in coordinates, from all users of the application?

Question

Explanation/Scenario:

I am developing an application that must redeem in real time the location of users of the same, and these users aware of this, will also, access the location of other users, in a map, to meet:

This location must be in real time, because all users have access to the map, and use it to find each other.

Question:

How to make my application rescue in real time this location of all users, (in coordinates) so that later I can use these coordinates and show the location on the map of each user?

Observing:

I’m not asking for an entire application, nor for them to do one for me, I just want to know how to redeem the coordinate of each user of the application :) but if you want to respond more fully including the part that shows the user with such coordinate on the map, it would be extremely useful!

Answer 1

If what you want is an app ready, click here, otherwise, adapt the code below.

Kickoff:

There are several examples on the web, but I started from a reply from Soen himself:

First of all, this has to be in the application manifest:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

Example of use of the class below:

LocationResult locationResult = new LocationResult(){
    @Override
    public void gotLocation(Location location){
        //Usar a localizacao aqui!
    }
};
MyLocation myLocation = new MyLocation();
myLocation.getLocation(this, locationResult);

Mylocation class:

import java.util.Timer;
import java.util.TimerTask;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class MyLocation {
    Timer timer1;
    LocationManager lm;
    LocationResult locationResult;
    boolean gps_enabled=false;
    boolean network_enabled=false;

    public boolean getLocation(Context context, LocationResult result)
    {
        //É usado o callback LocationResult para passar as coordenadas para o codigo do usuario.
        locationResult=result;
        if(lm==null)
            lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

        //se o provedor de localizacao nao estiver habilitado, teremos uma excecao.
        try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
        try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}

        //Codigo para nao tentar fazer a leitura sem provedor de localizacao disponivel
        if(!gps_enabled && !network_enabled)
            return false;

        if(gps_enabled)
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
        if(network_enabled)
            lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
        timer1=new Timer();
        timer1.schedule(new GetLastLocation(), 20000);
        return true;
    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerNetwork);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    class GetLastLocation extends TimerTask {
        @Override
        public void run() {
             lm.removeUpdates(locationListenerGps);
             lm.removeUpdates(locationListenerNetwork);

             Location net_loc=null, gps_loc=null;
             if(gps_enabled)
                 gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
             if(network_enabled)
                 net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

             //se tiver os dois valores, usar o mais atualizado
             if(gps_loc!=null && net_loc!=null){
                 if(gps_loc.getTime()>net_loc.getTime())
                     locationResult.gotLocation(gps_loc);
                 else
                     locationResult.gotLocation(net_loc);
                 return;
             }

             if(gps_loc!=null){
                 locationResult.gotLocation(gps_loc);
                 return;
             }
             if(net_loc!=null){
                 locationResult.gotLocation(net_loc);
                 return;
             }
             locationResult.gotLocation(null);
        }
    }

    public static abstract class LocationResult{
        public abstract void gotLocation(Location location);
    }
}

Note: Na original thread there are several points and interesting modifications, recommend reading.