当我使用 Retrofit 时，Google 位置服务返回一个空位置
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【中文标题】当我使用 Retrofit 时，Google 位置服务返回一个空位置【英文标题】：Google location services returning a null location when I use Retrofit 【发布时间】：2020-12-18 22:05:38 【问题描述】：我有一个片段，我想在其中获取当前坐标，然后使用 Retrofit 向 Zomato Api 发出请求，但我当前的位置返回 null。我试图删除与我的 api 调用相关的代码，应用程序返回我正确的纬度和经度。我在做什么错？下面是我的 Java 类。
我的片段
public class RestaurantsList extends Fragment
private RestaurantAdapter mAdapter;
private RecyclerView mRecyclerView;
protected static List<Restaurant_> restaurantsList;
private Context context;
protected static OnRestaurantClickedListener listener;
private FirebaseAuth mAuth;
private static final int REQUEST_FINE_LOCATION=100;
private LocationRequest mLocationRequest;
private LocationCallback mLocationCallback;
private FusedLocationProviderClient mFusedLocationClient;
private Location myLocation;
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
context = getContext();
mAuth = FirebaseAuth.getInstance();
restaurantsList= new ArrayList<>(50);
getLastLocation();
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(getActivity());
mFusedLocationClient.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>()
@Override
public void onSuccess(Location location)
if (location != null)
myLocation=location;
Toast.makeText( getActivity(),"Latitude: "+location.getLatitude()+" Longitude: "+location.getLongitude(), Toast.LENGTH_SHORT).show();
).addOnFailureListener(getActivity(), new OnFailureListener()
@Override
public void onFailure(@NonNull Exception e)
Toast.makeText( getActivity(),"It wasn´t possible to determine your location", Toast.LENGTH_SHORT).show();
);
getApi().getNearbyRestaurants(myLocation.getLatitude(),myLocation.getLongitude(),20,10000,"rating","desc","75be9f9e2239fe637bf9cb1b46979d91")
.enqueue(new Callback<ApiResponse>()
@Override
public void onResponse(Call<ApiResponse> call, Response<ApiResponse> response)
List<Restaurant> restaurants=response.body().getRestaurants();
mAdapter = new RestaurantAdapter(context, restaurantsList);
mRecyclerView.setAdapter(mAdapter);
RecyclerView.ItemDecoration itemDecoration = new DividerItemDecoration(context, DividerItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(itemDecoration);
for (int i = 0; i < restaurants.size(); i++)
restaurantsList.add(restaurants.get(i).getRestaurant());
mAdapter.notifyItemInserted(i);
@Override
public void onFailure(Call<ApiResponse> call, Throwable t)
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Couldn´t find any nearby restaurants");
AlertDialog mDialog = builder.create();
mDialog.show();
);
@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
View mContentView = inflater.inflate(R.layout.restaurants_list, container,false);
mRecyclerView = mContentView.findViewById(R.id.recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(mContentView.getContext()));
return mContentView;
@Override
public void onResume()
super.onResume();
@Override public void onAttach(Activity activity)
super.onAttach(activity);
try
listener= (OnRestaurantClickedListener) activity;
catch (ClassCastException e)
throw new ClassCastException(activity.toString() + " must implement OnButtonClicked");
private Retrofit getRetrofit()
return new Retrofit.Builder()
.baseUrl("https://developers.zomato.com/api/v2.1/")
.addConverterFactory(GsonConverterFactory.create())
.build();
private ZomatoApi getApi()
return getRetrofit().create(ZomatoApi.class);
private void getLastLocation()
if (ActivityCompat.checkSelfPermission(getContext(),
Manifest.permission.ACCESS_FINE_LOCATION )!= PackageManager.PERMISSION_GRANTED)
requestPermissions();
return;
private void requestPermissions()
ActivityCompat.requestPermissions(getActivity(),
new String[]Manifest.permission.ACCESS_FINE_LOCATION,
REQUEST_FINE_LOCATION);
新代码
public class RestaurantsList extends Fragment
private RestaurantAdapter mAdapter;
private RecyclerView mRecyclerView;
protected static List<Restaurant_> restaurantsList;
private Context context;
protected static OnRestaurantClickedListener listener;
private FirebaseAuth mAuth;
private static final int REQUEST_FINE_LOCATION=100;
private LocationRequest mLocationRequest;
private LocationCallback mLocationCallback;
private FusedLocationProviderClient mFusedLocationClient;
private static final String TAG = "LOCATION";
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
context = getContext();
mAuth = FirebaseAuth.getInstance();
restaurantsList= new ArrayList<>(50);
getLastLocation();
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(getActivity());
@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
View mContentView = inflater.inflate(R.layout.restaurants_list, container,false);
mRecyclerView = mContentView.findViewById(R.id.recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(mContentView.getContext()));
return mContentView;
@Override
public void onResume()
super.onResume();
@Override public void onAttach(Activity activity)
super.onAttach(activity);
try
listener= (OnRestaurantClickedListener) activity;
catch (ClassCastException e)
throw new ClassCastException(activity.toString() + " must implement OnButtonClicked");
private Retrofit getRetrofit()
return new Retrofit.Builder()
.baseUrl("https://developers.zomato.com/api/v2.1/")
.addConverterFactory(GsonConverterFactory.create())
.build();
private ZomatoApi getApi()
return getRetrofit().create(ZomatoApi.class);
private void getLastLocation()
if (ActivityCompat.checkSelfPermission(getContext(),
Manifest.permission.ACCESS_FINE_LOCATION )!= PackageManager.PERMISSION_GRANTED)
requestPermissions();
return;
private void requestPermissions()
ActivityCompat.requestPermissions(getActivity(),
new String[]Manifest.permission.ACCESS_FINE_LOCATION,
REQUEST_FINE_LOCATION);
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
if (requestCode == REQUEST_FINE_LOCATION)
if (grantResults.length <= 0)
// If user interaction was interrupted, the permission request is cancelled and you
// receive empty arrays.
Log.i(TAG, "User interaction was cancelled.");
else if (grantResults[0] == PackageManager.PERMISSION_GRANTED)
// Permission granted.
getRestaurants();
private void getRestaurants()
mFusedLocationClient.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>()
@Override
public void onSuccess(Location location)
if (location != null)
getApi().getNearbyRestaurants(location.getLatitude(),location.getLongitude(),20,10000,"rating","desc","75be9f9e2239fe637bf9cb1b46979d91")
.enqueue(new Callback<ApiResponse>()
@Override
public void onResponse(Call<ApiResponse> call, Response<ApiResponse> response)
List<Restaurant> restaurants=response.body().getRestaurants();
mAdapter = new RestaurantAdapter(context, restaurantsList);
mRecyclerView.setAdapter(mAdapter);
RecyclerView.ItemDecoration itemDecoration = new DividerItemDecoration(context, DividerItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(itemDecoration);
for (int i = 0; i < restaurants.size(); i++)
restaurantsList.add(restaurants.get(i).getRestaurant());
mAdapter.notifyItemInserted(i);
@Override
public void onFailure(Call<ApiResponse> call, Throwable t)
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Couldn´t find any nearby restaurants");
AlertDialog mDialog = builder.create();
mDialog.show();
);
).addOnFailureListener(getActivity(), new OnFailureListener()
@Override
public void onFailure(@NonNull Exception e)
Toast.makeText( getActivity(),"It wasn´t possible to determine your location", Toast.LENGTH_LONG).show();
);
【问题讨论】：
【参考方案1】：您正在执行两个异步任务，这两个任务都将在未来某个时间点完成（获取位置和进行 Zomato API 调用）。但是你在这里同时做它们。即使位置代码在 API 调用代码之上，它实际上并没有在执行 API 调用之前等待位置。
您需要做的是将 Zomato API 调用移至其自己的方法。然后从 FusedLocationProvider 的onSuccess(Location) 回调方法中调用该方法。这样，您在尝试使用该位置之前等待该位置进入。
【讨论】：
我已经解决了?但是我有一个小错误。如果是第一次使用该应用程序，它会显示 onFailure toast，然后向我显示授权对话框，导致响应为空。关于如何解决这个问题的任何提示？ 您的意思是位置权限对话框？ 请求Location运行时权限有很多步骤，特别是如果你想正确地做到这一点：github.com/android/location-samples/blob/master/BasicLocation/… 是的。如果是第一次，它首先显示 toast，然后才显示权限对话框。如果不是，应用程序运行正常 查看上面链接中的代码。您必须将其视为另一个回调。所以你请求Location权限，然后你可以从onRequestPermissionsResult()方法实际获取Location，然后从FusedLocationProvider的onSuccess(Location)回调方法你最终可以调用Zomato API。以上是关于当我使用 Retrofit 时，Google 位置服务返回一个空位置的主要内容，如果未能解决你的问题，请参考以下文章
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