纬度和经度未被检索

Question

当gps被禁用时，您可以使用Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);启用它，但是当我返回活动时，我没有得到任何结果。我必须重新启动活动，换句话说，我必须回到之前的活动，然后重新打开它。请你帮助我好吗？

这是我的doInBackground方法：

@Override
protected String doInBackground(String... uri){

    final GPSTracker gpsTracker = new GPSTracker(myactivity);
    final String[] latitudine = {null};
    final String[] longitudine = {null};

    if(gpsTracker.canGetLocation())
    {
        latitudine[0] = String.valueOf(gpsTracker.latitude);
        longitudine[0] = String.valueOf(gpsTracker.longitude);
    }
    else
    {
        myactivity.runOnUiThread(new Runnable() {
            public void run() {

                final Dialog dialog = new Dialog(myactivity);
                dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
                dialog.setContentView(R.layout.position_alert_dialog);

                Button dialogButton_deny = (Button) dialog.findViewById(R.id.deny);
                Button dialogButton_allow = (Button) dialog.findViewById(R.id.allow);

                dialogButton_allow.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                        myactivity.startActivity(intent);
                        dialog.dismiss();

                        if(gpsTracker.canGetLocation())
                        {
                            latitudine[0] = String.valueOf(gpsTracker.latitude);
                            longitudine[0] = String.valueOf(gpsTracker.longitude);

                        }else{

                            latitudine[0] = "34.0522300";
                            longitudine[0] = "-118.2436800";

                        }

                    }
                });

                dialogButton_deny.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        dialog.dismiss();
                    }
                });

                dialog.show();

            }
        });
    }

GPSTracker：

public class GPSTracker extends Service implements LocationListener {
    private final Context mContext;

    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; //10 meters

    private static final long MIN_TIME_BW_UPDATES = 1000 * 60; // 1 minute

    protected LocationManager locationManager;

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

    public Location getLocation() {
        try {
            locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

            isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

            isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            if (!isGPSEnabled && !isNetworkEnabled) {
            } else {
                this.canGetLocation = true;
                if (isNetworkEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this, Looper.getMainLooper());

                    Log.d("Network", "Network");

                    if (locationManager != null) {
                        location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        updateGPSCoordinates();
                    }
                }
                if (isGPSEnabled) {
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                        Log.d("GPS Enabled", "GPS Enabled");

                        if (locationManager != null) {
                            location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            updateGPSCoordinates();
                        }
                    }
                }
            }
        } catch (Exception e) {
            //e.printStackTrace();
            Log.e("Error : Location", "Impossible to connect to LocationManager", e);
        }

        return location;
    }

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

    public void stopUsingGPS() {
        if (locationManager != null) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    // TODO: Consider calling
                    //    public void requestPermissions(@NonNull String[] permissions, int requestCode)
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for Activity#requestPermissions for more details.
                    return;
                }
            }
            locationManager.removeUpdates(GPSTracker.this);
        }
    }

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

        return latitude;
    }

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

        return longitude;
    }

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

    public List<Address> getGeocoderAddress(Context context)
    {
        if (location != null)
        {
            Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
            try
            {
                return geocoder.getFromLocation(latitude, longitude, 1);
            }
            catch (IOException e)
            {
                //e.printStackTrace();
                Log.e("Error : Geocoder", "Impossible to connect to Geocoder", e);
            }
        }

        return null;
    }

    public String getAddressLine(Context context)
    {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        {
            Address address = addresses.get(0);

            return address.getAddressLine(0);
        }
        else
        {
            return null;
        }
    }

    public String getLocality(Context context)
    {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        {
            Address address = addresses.get(0);

            return address.getLocality();
        }
        else
        {
            return null;
        }
    }

    public String getSubLocality(Context context)
    {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        {
            Address address = addresses.get(0);

            return address.getSubLocality();
        }
        else
        {
            return null;
        }
    }

    public String getPostalCode(Context context)
    {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        {
            Address address = addresses.get(0);

            return address.getPostalCode();
        }
        else
        {
            return null;
        }
    }

    public String getCountryName(Context context)
    {
        List<Address> addresses = getGeocoderAddress(context);
        if (addresses != null && addresses.size() > 0)
        {
            Address address = addresses.get(0);

            return address.getCountryName();
        }
        else
        {
            return null;
        }
    }

    @Override
    public void onLocationChanged(Location location)
    {
    }

    @Override
    public void onProviderDisabled(String provider)
    {
    }

    @Override
    public void onProviderEnabled(String provider)
    {
    }    

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras)
    {
    }

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

修改

public class GPSTracker extends Service implements LocationListener, GoogleApiClient.ConnectionCallbacks {
private final Context mContext;

boolean isPlayServicesEnabled = false;

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; //10 meters

private static final long MIN_TIME_BW_UPDATES = 1000 * 60; // 1 minute

protected LocationManager locationManager;

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

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

        isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

        isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
        } else {
            this.canGetLocation = true;
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this, Looper.getMainLooper());

                Log.d("Network", "Network");

                if (locationManager != null) {
                    location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    updateGPSCoordinates();
                }
            }
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    Log.d("GPS Enabled", "GPS Enabled");

                    if (locationManager != null) {
                        location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        updateGPSCoordinates();
                    }
                }
            }
        }
    } catch (Exception e) {
        //e.printStackTrace();
        Log.e("Error : Location", "Impossible to connect to LocationManager", e);
    }

    return location;
}

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

public void stopUsingGPS() {
    if (locationManager != null) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    public void requestPermissions(@NonNull String[] permissions, int requestCode)
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for Activity#requestPermissions for more details.
                return;
            }
        }
        locationManager.removeUpdates(GPSTracker.this);
    }
}

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

    return latitude;
}

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

    return longitude;
}

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

public List<Address> getGeocoderAddress(Context context) {
    if (location != null) {
        Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
        try {
            return geocoder.getFromLocation(latitude, longitude, 1);
        } catch (IOException e) {
            //e.printStackTrace();
            Log.e("Error : Geocoder", "Impossible to connect to Geocoder", e);
        }
    }

    return null;
}

public String getAddressLine(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);

        return address.getAddressLine(0);
    } else {
        return null;
    }
}

public String getLocality(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);

        return address.getLocality();
    } else {
        return null;
    }
}

public String getSubLocality(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);

        return address.getSubLocality();
    } else {
        return null;
    }
}

public String getPostalCode(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);

        return address.getPostalCode();
    } else {
        return null;
    }
}

public String getCountryName(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);

        return address.getCountryName();
    } else {
        return null;
    }
}

@Override
public void onLocationChanged(Location location) {

    this.location = location;

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {

}

@Override
public void onProviderDisabled(String provider) {
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onConnected(Bundle connectionHint) {
    isPlayServicesEnabled = true;
    getLocation();
}

@Override
public void onConnectionSuspended(int cause) {
    isPlayServicesEnabled = false;
}

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

}

这就是我称之为AsyncTask的地方：

public class Weather extends AppCompatActivity{

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.meteo_nuovo);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_layout);
    setSupportActionBar(toolbar);

    toolbar.setPadding(0, getStatusBarHeight(), 0, 0);

    assert getSupportActionBar() != null;

    this.getSupportActionBar().setDisplayHomeAsUpEnabled(true);    
    this.getSupportActionBar().setDisplayShowTitleEnabled(false);  

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
        getWindow().getDecorView().setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
    }

    new WeatherApi(this).execute();  // the doInBackground method above is from this class

}

public int getStatusBarHeight() {
    int result = 0;

    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
        int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
        if (resourceId > 0) {
            result = getResources().getDimensionPixelSize(resourceId);
        }
    }
    return result;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

}

Answer 1

就我这个问题而言，我已经按照自己的方式解决了这个问题。

在GPSTracker课程中制作一种方法。

public void onActivityResult(int requestCode, int resultcode, Intent data) {

}

现在使用startActivityForResult代替startActivity，

开始活动

Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivityForResult(intent, 0);

当您回到onActivityResult方法

时，现在正处于您的活动中

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    gpsTracker.onActivityResult(requestCode, resultCode, data);// This line is more important 

    if (requestCode == 0) {

        handler.sendEmptyMessage(0);

    }
}

现在handler是

android.os.Handler handler = new android.os.Handler(new android.os.Handler.Callback() {
    @Override
    public boolean handleMessage(Message message) {
        try {
              Location location = gpsTracker.getLocation();
              latitude = location.getLatitude();
              longitude = location.getLongitude();
        } catch (Exception e) {
            Log.v("Error:", "Location is null");
        }
        return false;
    }
});

使用此功能，您可以随时移动位置。可能会有所帮助。在我的情况下它工作正常。

Answer 2

使用getLastKnownLocation有时会导致问题，因为实际找到lastKnownLocation可能需要一些时间。

尝试使用onLocationChanged函数设置您的位置，这应该可以有效地消除此问题。

您可以按照以下方式执行此操作：

@Override
public void onLocationChanged(Location location)
{
    this.location = location;
}

现在，每次更改位置（或第一次找到）时，都会调用onLocationChanged事件，并将GPSTracker位置变量设置为调用参数中传递的位置！

修改

尝试将GPSTracker类更改为以下内容：

public class GPSTracker extends Service implements LocationListener, ConnectionCallbacks {
private final Context mContext;

boolean isPlayServicesEnabled = false;

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; //10 meters

private static final long MIN_TIME_BW_UPDATES = 1000 * 60; // 1 minute

protected LocationManager locationManager;

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

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

        isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

        isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
        } else {
            this.canGetLocation = true;
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this, Looper.getMainLooper());

                Log.d("Network", "Network");

                if (locationManager != null) {
                    location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    updateGPSCoordinates();
                }
            }
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    Log.d("GPS Enabled", "GPS Enabled");

                    if (locationManager != null) {
                        location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        updateGPSCoordinates();
                    }
                }
            }
        }
    } catch (Exception e) {
        //e.printStackTrace();
        Log.e("Error : Location", "Impossible to connect to LocationManager", e);
    }

    return location;
}

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

public void stopUsingGPS() {
    if (locationManager != null) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    public void requestPermissions(@NonNull String[] permissions, int requestCode)
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for Activity#requestPermissions for more details.
                return;
            }
        }
        locationManager.removeUpdates(GPSTracker.this);
    }
}

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

    return latitude;
}

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

    return longitude;
}

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

public List<Address> getGeocoderAddress(Context context)
{
    if (location != null)
    {
        Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
        try
        {
            return geocoder.getFromLocation(latitude, longitude, 1);
        }
        catch (IOException e)
        {
            //e.printStackTrace();
            Log.e("Error : Geocoder", "Impossible to connect to Geocoder", e);
        }
    }

    return null;
}

public String getAddressLine(Context context)
{
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0)
    {
        Address address = addresses.get(0);

        return address.getAddressLine(0);
    }
    else
    {
        return null;
    }
}

public String getLocality(Context context)
{
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0)
    {
        Address address = addresses.get(0);

        return address.getLocality();
    }
    else
    {
        return null;
    }
}

public String getSubLocality(Context context)
{
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0)
    {
        Address address = addresses.get(0);

        return address.getSubLocality();
    }
    else
    {
        return null;
    }
}

public String getPostalCode(Context context)
{
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0)
    {
        Address address = addresses.get(0);

        return address.getPostalCode();
    }
    else
    {
        return null;
    }
}

public String getCountryName(Context context)
{
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0)
    {
        Address address = addresses.get(0);

        return address.getCountryName();
    }
    else
    {
        return null;
    }
}

@Override
public void onLocationChanged(Location location)
{
}

@Override
public void onProviderDisabled(String provider)
{
}

@Override
public void onProviderEnabled(String provider)
{
}

@Override
public void onConnected(Bundle connectionHint) {
    isPlayServicesEnabled = true;
    getLocation();
}

@Override
public void onConnectionSuspended(int cause) {
    isPlayServicesEnabled = false;
}

我认为可能导致您的问题的原因是您不检查Google Play服务是否已连接。在上面的代码中，我实现了ConnectionCallbacks并包含onConnected和onConnectionSuspended覆盖。现在，只有在连接了Play服务后才会调用getLocation（）。如果有问题，请告诉我。

Answer 3

我假设您在活动的doInBackground()方法中调用onCreate()方法因此，如果未启用GPS，则您的应用程序会重定向到GPS设置屏幕。

因此，当您启用GPS简历后，从Activity设置屏幕返回，这样就不会再次致电doInBackground()，这就是为什么您没有获得任何结果。

最简单的解决方案是为onResume()定义Activity方法并在doInBackground()而不是onResume()中致电onCreate()，以便当您的活动恢复时，它会调用doInBackground()再次获得更新结果。

你应该像这样更新你的活动：

public class Weather extends AppCompatActivity{

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.meteo_nuovo);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_layout);
    setSupportActionBar(toolbar);

    toolbar.setPadding(0, getStatusBarHeight(), 0, 0);

    assert getSupportActionBar() != null;

    this.getSupportActionBar().setDisplayHomeAsUpEnabled(true);    
    this.getSupportActionBar().setDisplayShowTitleEnabled(false);  

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
        getWindow().getDecorView().setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
    }  
}

@Override
public void onResume(){
    super.onResume();
   new WeatherApi(this).execute();  // the doInBackground method above is from this class

}

public int getStatusBarHeight() {
    int result = 0;

    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {
        int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
        if (resourceId > 0) {
            result = getResources().getDimensionPixelSize(resourceId);
        }
    }
    return result;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}
}

我希望它可以帮到你。