android - 无法使用通用代码获取 GPS 位置

Question

我有获取位置的代码，我相信它一定可以工作，但根本不起作用:

list :

<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 并且监听器根本不会被调用。任何人都可以建议出了什么问题？如果我打开 Google map ，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

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了 this is reference to your activity

 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 已开启并设置为高精度。并且在 list 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" />