Question

我无法理解我的代码中强制需要权限检查。

此外，即使这样做，该位置也为空。

这是我的onCreate方法的代码：请帮忙!!

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

    textView = (TextView) findViewById(R.id.textView);

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    provider = locationManager.getBestProvider(new Criteria(), false);

    if(provider.equals(null)){
        Log.i("provdier","prob");
    }

    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;
    }


    Location location = locationManager.getLastKnownLocation(provider);

    if (location != null) {
        Log.i("location info", "achieved");
        textView.setText("Achieved");
    } else {
        Log.i("location info", "failed");
        textView.setText("Failed");
    }
}

Answer 1

试试这个。

 private Location getLastKnownLocation() {

       LocationManager mLocationManager = (LocationManager) getApplicationContext().getSystemService(LOCATION_SERVICE);
        List<String> providers = mLocationManager.getProviders(true);
        Location bestLocation = null;

        for (String provider : providers) {

            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 TODO;
            }
            Location l = mLocationManager.getLastKnownLocation(provider);
            if (l == null) {
                continue;
            }
            if (bestLocation == null || l.getAccuracy() < bestLocation.getAccuracy()) {
                // Found best last known location: %s", l);
                bestLocation = l;
            }
        }
        return bestLocation;


    }

Answer 2

我遇到了同样的问题但是developer.android.com拯救了。

只需访问这两个链接，问题就会解决：

Last Known location
Requesting Permissions

仍供参考。我的代码：

public class MainActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks, OnConnectionFailedListener {

GoogleApiClient mGoogleApiClient;
Location mLastLocation;
TextView mLatitudeText, mLongitudeText;
final int MY_PERMISSIONS_REQUEST_MAPS = 1;

protected void onStart() {
    mGoogleApiClient.connect();
    super.onStart();
}

protected void onStop() {
    mGoogleApiClient.disconnect();
    super.onStop();
}

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

    mLatitudeText = (TextView) findViewById(R.id.textView);
    mLongitudeText = (TextView) findViewById(R.id.textView2);

    if (mGoogleApiClient == null) {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }
    Log.i("permit Fine", ""+ ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION));
    Log.i("permit coarse", ""+ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION));
}

@Override
public void onConnected(@Nullable Bundle bundle) {
    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.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.
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.READ_CONTACTS)) {

            // Show an explanation to the user *asynchronously* -- don't block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.
            Log.i("in","Explaination");

        } else {

            // No explanation needed, we can request the permission.

            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION,Manifest.permission.ACCESS_COARSE_LOCATION},
                    MY_PERMISSIONS_REQUEST_MAPS);
            Log.i("in","Else");

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
        return;
    }
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
            mGoogleApiClient);
    if (mLastLocation != null) {
        mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude()));
        mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude()));
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_MAPS: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the
                // contacts-related task you need to do.
                Log.i("permit Fine", ""+ ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION));
                Log.i("permit coarse", ""+ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION));

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

}

}

强制许可检查仍然是location = null

2 个答案: