android - 如何在 Android 应用程序中使用 Google API 获取当前 GPS 位置(经纬度)？

Question

我想使用 Google API 获取 GPS 位置。

我的代码:

mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

@Override
public void onConnected(Bundle bundle) {  
    mLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    double lat = mLocation.getLatitude();
    double lon = mLocation.getLongitude();
}

我在 lat 和 lon 变量中没有得到任何东西。

如何解决？

Answer 1

LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient); 不一定总是返回最后一个对象。如果它没有找到最后一个对象，它将返回 null 并且您将无法获得位置。在这种情况下，建议使用以下方式请求位置:

LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
                mLocationRequest, this); 

您还需要实现一些接口(interface)并覆盖方法以通过 Google API 获取位置。

按照以下步骤获取位置:

首先，将其放入gradle文件

compile 'com.google.android.gms:play-services:8.4.0'

然后实现必要的接口(interface)

public class MainActivity  extends BaseActivitiy implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, com.google.android.gms.location.LocationListener

声明实例

private GoogleApiClient mGoogleApiClient;
  private Location mLocation;
  private LocationManager locationManager;
  private LocationRequest mLocationRequest;

把这个放在 onCreate()

 mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

最后，覆盖必要的方法

@Override
    public void onConnected(Bundle bundle) {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // 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 ActivityCompat#requestPermissions for more details.
            return;
        }
        mLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if(mLocation == null){
            startLocationUpdates();
        }
        if (mLocation != null) {
            double latitude = mLocation.getLatitude();
            double longitude = mLocation.getLongitude();
        } else {
            // Toast.makeText(this, "Location not Detected", Toast.LENGTH_SHORT).show();
        }
    }

    protected void startLocationUpdates() {
        // Create the location request
        mLocationRequest = LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(UPDATE_INTERVAL)
                .setFastestInterval(FASTEST_INTERVAL);
        // Request location updates
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // 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 ActivityCompat#requestPermissions for more details.
            return;
        }
        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,
                mLocationRequest, this);
        Log.d("reque", "--->>>>");
    }

    @Override
    public void onConnectionSuspended(int i) {
        Log.i(TAG, "Connection Suspended");
        mGoogleApiClient.connect();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.i(TAG, "Connection failed. Error: " + connectionResult.getErrorCode());
    }

    @Override
    public void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }

    @Override
    public void onStop() {
        super.onStop();
        if (mGoogleApiClient.isConnected()) {
            mGoogleApiClient.disconnect();
        }
    }
    @Override
    public void onLocationChanged(Location location) {

    }