无法使用通用代码获取 GPS 位置

Question

我有获取位置的代码，我认为它必须有效，但它根本不起作用：

清单：

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

Java：

    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    locationManager.requestLocationUpdates(
            LocationManager.GPS_PROVIDER, 
            0, 
            0,
            new MyLocationListener()
    );

    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    criteria.setAltitudeRequired(false);
    criteria.setBearingRequired(false);
    criteria.setCostAllowed(true);
    criteria.setPowerRequirement(Criteria.POWER_LOW);

    String provider = locationManager.getBestProvider(criteria, true);

    Location location = locationManager.getLastKnownLocation(provider);
    System.out.println("location: " + location);

location 打印 null 并且侦听器根本不会被调用。任何人都可以建议有什么问题吗？如果我打开 Google 地图，它仍然可以返回我的位置。

注意：我正在使用我的设备进行测试

Answer 1

添加此 Gps 跟踪器类

public class GPSTracker extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude

// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 30 * 1; // 30 seconds

// Declaring a Location Manager
protected LocationManager locationManager;

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

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

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {

            // no network provider is enabled

        } else {
            this.canGetLocation = true;
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
            // if GPS Enabled get lat/long using GPS Services
            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);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
        }

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

    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */
public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(GPSTracker.this);
    }       
}

/**
 * Function to get latitude
 * */
public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */
public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
        dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location location) {
   if(location!=null) {

       try {
        latitude=location.getLatitude();
        longitude=location.getLongitude();
    }
    catch (Exception e){
        e.printStackTrace();
    }
    }
}

@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 arg0) {
    return null;
}

}

并从以下代码中获取 Lat & Long 值，

 double lat=gpstracker.getLatitude();
 double long=gpstracker.getLongitude();

简单教程，

http://www.androidhive.info/2012/07/android-gps-location-manager-tutorial/

Answer 2

在您的实用程序包中或您可以使用以下代码的任何地方创建类SingleShotLocationProvider。

import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.widget.Toast;

public class SingleShotLocationProvider {

    public  interface LocationCallback {
         void onNewLocationAvailable(Location location);
    }

    // calls back to calling thread, note this is for low grain: if you want higher precision, swap the
    // contents of the else and if. Also be sure to check gps permission/settings are allowed.
    // call usually takes <10ms
    public static void requestSingleUpdate(final Context context, final LocationCallback callback) {
        final LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);


        if (Utility.checkAndRequestPermissionsForGPS(context)) {
            if (ActivityCompat.checkSelfPermission(context, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(context, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(context, "First enable LOCATION ACCESS in settings.", Toast.LENGTH_LONG).show();
                return;
            }
            boolean isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

            if (isGPSEnabled) {
                Criteria criteria = new Criteria();
                criteria.setAccuracy(Criteria.ACCURACY_FINE);
                locationManager.requestSingleUpdate(criteria, new LocationListener() {
                    @Override
                    public void onLocationChanged(Location location) {
                        callback.onNewLocationAvailable(location);
                    }

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

                    @Override
                    public void onProviderEnabled(String provider) {
                    }

                    @Override
                    public void onProviderDisabled(String provider) {
                    }
                }, null);
            } else {
                boolean isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
                if (isNetworkEnabled) {
                    Criteria criteria = new Criteria();
                    criteria.setAccuracy(Criteria.ACCURACY_COARSE);
                    locationManager.requestSingleUpdate(criteria, new LocationListener() {
                        @Override
                        public void onLocationChanged(Location location) {
                            callback.onNewLocationAvailable(location);
                        }

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

                        @Override
                        public void onProviderEnabled(String provider) {
                        }

                        @Override
                        public void onProviderDisabled(String provider) {
                        }
                    }, null);
                }
            }
        }

    }

}

现在在你的 Activity 中像这样导入它

import com.yourdomain.utils.SingleShotLocationProvider;

现在你可以像下面这样使用它 this 是对你的活动的引用

 SingleShotLocationProvider.requestSingleUpdate(this,
                    new SingleShotLocationProvider.LocationCallback() {
                        @Override
                        public void onNewLocationAvailable(Location location) {
                            if (location != null) {
                                double latitude = location.getLatitude();
                                double longitude = location.getLongitude();
                                }
                             } 
                    }
                });

您将在第一次尝试时收到位置，只需确保 GPS 已打开并设置为高精度。在清单中您已授予必要的权限，如下所示 -

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

Answer 3

试试这个代码。我在这里使用 GPS 来获取纬度和经度。

   Criteria criteria = new Criteria();

    // Getting the name of the best provider
    provider = locationManager.getBestProvider(criteria, true);

    // Getting Current Location
    location = locationManager.getLastKnownLocation(provider);

    if (location != null) {
        System.out.println("Get Last LOcation" + location.getLatitude()
                + location.getLongitude());
        loc.setLatitude(location.getLatitude());
        loc.setLongitude(location.getLongitude());

    }
    locationListener = new LocationListener() {

        @Override
        public void onStatusChanged(String provider, int status,
                Bundle extras) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderEnabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onProviderDisabled(String provider) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onLocationChanged(Location location) {
            // TODO Auto-generated method stub
            if (location.getAccuracy() < 50) {
                locationManager.removeUpdates(locationListener);
            }
        }
    };

    locationManager.requestLocationUpdates(provider,
            INTERVAL_TIME_SECONDS, MIN_DISTANCE_METERS,
            locationListener);