Question

我尝试使用函数getLastKnownLocation（）来获取Last Known Location以获取在textField中设置它的纬度和经度，但是名为location的Location实例返回null因此它无法获得经度和经度并且设置textField位置不可用如何修复它获得最后的位置？!!

                public class ShowLocationActivity extends Activity implements LocationListener {
                private TextView latituteField;
                private TextView longitudeField;
                private LocationManager locationManager;
                private String provider;

                /** Called when the activity is first created. */
                @Override
                public void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.activity_show_location);
                    latituteField = (TextView) findViewById(R.id.TextView02);
                    longitudeField = (TextView) findViewById(R.id.TextView04);

                    // Get the location manager
                    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
                    // Define the criteria how to select the locatioin provider -> use
                    // default
                    Criteria criteria = new Criteria();
                    provider = locationManager.getBestProvider(criteria, false);
                    if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION)
                            == PackageManager.PERMISSION_GRANTED)
                    {
                        Location location = locationManager.getLastKnownLocation(provider);

                        // Initialize the location fields
                        if (location != null) {
                            System.out.println("Provider4 " + provider + " has been selected.");
                            onLocationChanged(location);
                        } else {
                            latituteField.setText("Location not available");
                            longitudeField.setText("Location not available");
                        }
                    }
                }

                /* Request updates at startup */
                @Override
                protected void onResume() {
                    super.onResume();
                    if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
                            == PackageManager.PERMISSION_GRANTED)
                    locationManager.requestLocationUpdates(provider, 400, 1, this);
                }

                /* Remove the locationlistener updates when Activity is paused */
                @Override
                protected void onPause() {
                    super.onPause();
                    if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
                            == PackageManager.PERMISSION_GRANTED)
                    locationManager.removeUpdates(this);
                }

                @Override
                public void onLocationChanged(Location location) {
                    int lat = (int) (location.getLatitude());
                    int lng = (int) (location.getLongitude());
                    latituteField.setText(String.valueOf(lat));
                    longitudeField.setText(String.valueOf(lng));
                }

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

                }

                @Override
                public void onProviderEnabled(String provider) {
                    Toast.makeText(this, "Enabled new provider " + provider,
                            Toast.LENGTH_SHORT).show();

                }

                @Override
                public void onProviderDisabled(String provider) {
                    Toast.makeText(this, "Disabled provider " + provider,
                            Toast.LENGTH_SHORT).show();
                }
            }

}

Answer 1

使用此代码snipet获取上次已知位置：

添加依赖：

implementation 'com.google.android.gms:play-services-location:11.4.0'

并添加权限：

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

然后：

 @SuppressWarnings("MissingPermission")
    private void getLastLocation() {
     FusedLocationProviderClient   mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);

        mFusedLocationClient.getLastLocation()
                .addOnCompleteListener(new OnCompleteListener<Location>() {
                    @Override
                    public void onComplete(@NonNull Task<Location> task) {
                        if (task.isSuccessful() && task.getResult() != null) {
                            mLastLocation = task.getResult();
                            double lat = mLastLocation.getLatitude();
                            double log = mLastLocation.getLongitude();
                            Log.d(TAG, "lat:"+lat+"::"+log);

                        } else {
                            Timber.w("getLastLocation:exception::" + task.getException());

                        }
                    }
                });
    }

了解更多详情goto Getting the Last Known Location

如何使用函数getLastKnownLocation（）？

1 个答案: