public class RouteFragment extends Fragment implements LocationListener {

MapView mMapView;
private GoogleMap googleMap;
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
private String startLocation, endLocation = "";
private LatLng start, end;
private CarouselView carouselView;
private String estimatedDistance = "0km";
private TextView costPerMile;
public int counter = 0;
public static final String[] vehicleList = {"ambulance", "wheelchair", "star"};
private int chosenVehicle = 0;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    final View view = inflater.inflate(R.layout.fragment_route, container, false);
    final Context context = getActivity().getApplicationContext();
    Bundle bundle = this.getArguments();
    if (bundle != null) {
        startLocation = bundle.getString("start_location");
        endLocation = bundle.getString("end_location");
    }

    RequestQueue queue2 = Volley.newRequestQueue(context);
    StringRequest getRequest2 = new StringRequest(Request.Method.GET, (MainActivity.url + "/api/getLocation" + "?place=" + startLocation),
            new Response.Listener<String>()
            {
                @Override
                public void onResponse(String response) {
                    try {
                        JSONObject jresponse = new JSONObject(response);
                        Log.d("END", response);
                        Double lat = Double.valueOf(jresponse.getJSONObject("data").getString("lat"));
                        Double lng = Double.valueOf(jresponse.getJSONObject("data").getString("lng"));
                        start = new LatLng(lat,lng);

                    } catch (JSONException e) {
                        Log.d("ASD", "ERROR");
                        Log.d("ERROR", String.valueOf(e));
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener()
            {
                @Override
                public void onErrorResponse(VolleyError error) {
                    // error
                    Log.d("Error.Response", String.valueOf(error));
                }
            }
    ) {
        @Override
        public Map<String, String> getHeaders() throws AuthFailureError
        {
            Map<String, String> headers = new HashMap<String, String>();
            //Log.d("ASD", MainActivity.token);
            headers.put("x-access-token", MainActivity.token);
            headers.put("Content-Type","application/x-www-form-urlencoded");
            return headers;
        }
    };

    queue2.add(getRequest2);

    checkLocationPermission();
    FloatingActionButton fab = getActivity().findViewById(R.id.fab);
    fab.setVisibility(View.INVISIBLE);
    mMapView = view.findViewById(R.id.mapRoute);
    mMapView.onCreate(savedInstanceState);

    mMapView.onResume(); // needed to get the map to display immediately
    Log.d("ASD", "ASDASDASDASDASD");

当我运行此代码时，会打印检查 1 和检查 2(日志)，但 Volley 请求既没有给出错误也没有给出响应(因此没有其他日志消息被打印)。我尝试将 url 更改为无效的内容，然后它引发了 404 错误，但我确定 url 是正确的。我已经看了好几个小时了，当我在另一个 fragment 中运行它时，它运行得很完美。但它不会在这里运行，或者当我将它放在另一个按钮的 onClickListener 中时。

最佳答案

所以发现自己的错误:

创建谷歌地图是一个异步函数，就像我后端(node js)中的代码一样。为了解决这个问题，我将所有代码都放在了 onMapCreate 函数中。

//This goes in the onCreate
SupportMapFragment mapFragment = (SupportMapFragment) this.getChildFragmentManager()
            .findFragmentById(R.id.map);
            mapFragment.getMapAsync(this);

//This overrides the onMapReady function
@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    RequestQueue queue = Volley.newRequestQueue(getActivity().getApplicationContext());
    StringRequest getRequest = new StringRequest(Request.Method.GET, (MainActivity.url + "/api/getLocation" + "?place=" + startLocation),
            new Response.Listener<String>()
            {
                @Override
                public void onResponse(String response) {
                    try {
                        JSONObject jresponse = new JSONObject(response);
                    }
                    catch (JSONException e) {
                                    Log.d("ASD", "ERROR");
                                    Log.d("ERROR", String.valueOf(e));
                                    e.printStackTrace();
                    }
            new Response.ErrorListener()
            {
                @Override
                public void onErrorResponse(VolleyError error) {
                    // error
                    Log.d("Error.Response", String.valueOf(error));
                    }
            }
    )
queue.add(getRequest);

关于android - Volley Get 请求根本没有执行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51902828/