问：Android GPS位置

Question

I'm trying to access my GPS location of my device, so I can then use this to load Google maps on the user's coordinates. I have followed various guides, but I dont seem to be acquiring any correct values.

The app does not crash, it simply displays a zero

Here is the code for my maps activity:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

public class Maps extends ActionBarActivity {

Button btnLocation;
GPSTracker gps;


//private GoogleMap map;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //Hide action bar before Activity load
    getSupportActionBar().hide();
    setContentView(R.layout.activity_maps);


    btnLocation = (Button) findViewById(R.id.btnLocation);

    btnLocation.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            gps = new GPSTracker(Maps.this);

            if(gps.canGetLocation()){
                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();

                Toast.makeText(getApplicationContext(),
                        "Your location is -\nLat: " + latitude +
                        "\nLong: " + longitude, Toast.LENGTH_LONG).show();
            } else {
                gps.showSettingsAlert();
            }
        }
    });

Below is my code that is meant to obtain the location

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;

public class GPSTracker extends Service implements LocationListener {

    private final Context context;
//Flags for network/gps status
boolean isGPSEnabled = false;
boolean isNetworkEnabled = false;
boolean canGetLocation = false;

Location location;

double latitude;
double longitude;

private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10;
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1;

public LocationManager locationManager;

public GPSTracker(Context context) {
    this.context = context;
    getLocation();
}

public Location getLocation(){
    try {
        locationManager = (LocationManager) context.getSystemService(LOCATION_SERVICE);
        isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
        isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {

        } else {
            this.canGetLocation = true;
            //For use over networks
            if (isNetworkEnabled) {

                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                if (locationManager != null) {
                    location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

                    if (location != null) {
                      latitude = location.getLatitude();
                      longitude = location.getLongitude();
                    }
                }
            }
            //For use over GPS
            if (isGPSEnabled) {
                if(location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    if(locationManager != null) {
                        location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

                        if(location != null){
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }

        }
    } catch (Exception e ) {
        e.printStackTrace();
    }
    return location;
}



public void stopUsingGPS() {
    if(locationManager != null) {
        locationManager.removeUpdates(GPSTracker.this);
    }
}

public double getLatitude() {
    if (location != null) {
        latitude = location.getLatitude();
    } else {
        getLocation();
    }
    return latitude;
}

public double getLongitude() {
    if (location != null){
        longitude = location.getLongitude();
    } else {
        getLocation();
    }
    return longitude;
}



public void showSettingsAlert() {
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);

    alertDialog.setTitle("GPS is being set");

    alertDialog.setMessage("GPS is not enabled. Go to settings.");

    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            context.startActivity(intent);

        }
    });

    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    alertDialog.show();
}


public boolean canGetLocation() {
    return this.canGetLocation;
}

I have also included the necessary code into the manifest:

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

Help is greatly appreciated

Answer 1

DO NOT USE GPSTracker!!!! Dear god this code will not die. Its horrible, bad, awful code. I have a blog post at http://gabesechansoftware.com/location-tracking/ showing the dozen different ways that code is flawed. I also have a much better implementation available there. That code was written by someone who didn't fully understand location tracking, and it makes a lot of bad assumptions.

If I was allowed to delete one class from this website it would be all mentions of that one. Its just horribly naive code.