java - 删除位置管理器不起作用的更新

Question

我有一张 map ，我想在上面显示用户的当前位置，并且在获取用户的位置后调用 api 来获取附近的商家。

我正在获取用户的当前位置，所有商家也都通过 map 上的标记来获取位置。

但是我在LocationListener的onLocationChanged()方法中调用了setMap方法。该方法会被连续调用。

我想获取一次位置并显示在标记上，当下次用户访问此 fragment 时，我只想获取更新的位置。

但现在它会连续循环调用 onLocation 方法，因此会调用 accessMerchants。

为了阻止这个问题，我尝试从位置管理器中删除更新，我还尝试设置一个 boolean 变量，如果它第一次进入 onLocationChanged() 方法，它将是 false，但它也会再次进入循环。

删除更新也不起作用，如果删除更新起作用，那么 onLocationChanged 方法不应该再次被调用，对吗？

public class SearchMerchantFragment extends Fragment implements GetSearchedMerchantsAsyncTask.GetSearchedMerchantsCallBack, OnMapReadyCallback, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {

    LocationListener[] mLocationListeners = new LocationListener[]{
            new LocationListener(LocationManager.GPS_PROVIDER),
            new LocationListener(LocationManager.NETWORK_PROVIDER)
    };


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_search_merchant, container, false);

        setUpUI(view);

        return view;
    }


    public void setUpUI(View view) {

        initializeLocationManager();

        requestLocation();

        setUpMapIfNeeded();


        mLocationsList = new ArrayList<>();
        markers = new ArrayList<>();

        edtSearch = (EditText) view.findViewById(R.id.edtSearch);

        rv_fetch_merchants = (RecyclerView) view.findViewById(R.id.rv_fetch_merchants);
        merchantsList = new ArrayList<Merchants>();
        merchantsAdapter = new SearchedMerchantsAdapter(this.getContext(), merchantsList);
        rv_fetch_merchants.setLayoutManager(new LinearLayoutManager(getActivity()));
        rv_fetch_merchants.setAdapter(merchantsAdapter);
        rv_fetch_merchants.setHasFixedSize(true);
        rv_fetch_merchants.setItemViewCacheSize(30);
        rv_fetch_merchants.setDrawingCacheEnabled(true);
        rv_fetch_merchants.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);


    }

    //get searched merchants
    public void accessMerchants() {
          if (CommonUtils.isConnectedToInternet(getContext())) {
        new GetSearchedMerchantsAsyncTask(getActivity(), SearchMerchantFragment.this).execute(access_token, sessionUserId, String.valueOf(mLastLocation.getLatitude()), String.valueOf(mLastLocation.getLongitude()));
           } else {
           showAlert(String.valueOf(R.string.check_network));
          }
    }

    @Override
    public void doPostExecute(ArrayList<Merchants> merchantsArrayList) {

        merchantsList.clear();
        merchantsList.addAll(merchantsArrayList);
        merchantsAdapter.notifyDataSetChanged();

        for (Merchants merchants : merchantsList) {
            LatLng latLng = new LatLng(merchants.getLatitude(), merchants.getLongitude());
            MarkerOptions marker = new MarkerOptions().position(latLng).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)).title(merchants.getKirana_name());
            Marker m = mGoogleMap.addMarker(marker);
            markers.add(m);
        }

    }

    private void setUpMapIfNeeded() {
        if (mGoogleMap == null) {
            mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map_fragment);
            mapFragment.getMapAsync(this);
            // getLocation();
        }
    }

    //setup map

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mGoogleMap = googleMap;

        buildGoogleApiClient();

        mGoogleApiClient.connect();

    }

    protected synchronized void buildGoogleApiClient() {
        //   Toast.makeText(getActivity(),"buildGoogleApiClient",Toast.LENGTH_SHORT).show();
        mGoogleApiClient = new GoogleApiClient.Builder(getActivity())
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

    @Override
    public void onConnected(Bundle bundle) {
        // Toast.makeText(getActivity(),"onConnected",Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onConnectionSuspended(int i) {
        //  Toast.makeText(getActivity(),"onConnectionSuspended",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        //    Toast.makeText(getActivity(),"onConnectionFailed",Toast.LENGTH_SHORT).show();
    }

    private void removeMarkers() {
        if (mGoogleMap != null) {
            for (Marker marker : markers) {
                marker.remove();
            }
            mGoogleMap.clear();
            markers.clear();
        }
    }


    @Override
    public void onDetach() {
        super.onDetach();
        mapConnected = false;
    }

        return true;
    }

    public void setMap() {
        try {

            int locationPermission = ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION);
            int coarseLocation = ContextCompat.checkSelfPermission(getActivity(),Manifest.permission.ACCESS_COARSE_LOCATION);

            if(locationPermission == PackageManager.PERMISSION_GRANTED && coarseLocation == PackageManager.PERMISSION_GRANTED && GPSTracker.isGPSEnabled) {

                if(receivedLocation) {

                    receivedLocation = false;

                    mLatLang = new LatLng(mLastLocation.getLatitude(), mLastLocation.getLongitude());
                    accessMerchants();


                    MarkerOptions markerOptions = new MarkerOptions();
                    markerOptions.position(mLatLang);
                    markerOptions.title(getString(R.string.position));
                    markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE));
                    mMarker = mGoogleMap.addMarker(markerOptions);

                    CameraPosition cameraPosition = new CameraPosition.Builder().target(mLatLang).zoom(14).build();

                    mGoogleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

                    //  mLocationRequest = new LocationRequest();
                    // mLocationRequest.setInterval(5000); //5 seconds
                    // mLocationRequest.setFastestInterval(3000); //3 seconds
                    //  mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);

                    mGoogleMap.setMyLocationEnabled(true);
                    mGoogleMap.getUiSettings().setZoomControlsEnabled(true);
                    mGoogleMap.getUiSettings().setAllGesturesEnabled(true);

                    LocationListener locationListener = new LocationListener();
                    mLocationManager.removeUpdates(locationListener);

                }
            }
            else {
                showAlert(getString(R.string.locationAlert));
            }

        } catch (SecurityException e) {

        }
    }

    private void initializeLocationManager() {
       // Log.e(Application.TAG, "initializeLocationManager");
        if (mLocationManager == null) {
            mLocationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
        }

        boolean gps_enabled = false;
        boolean network_enabled = false;

        try {
            gps_enabled = mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
        } catch (Exception ex) {
        }

        try {
            network_enabled = mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        } catch (Exception ex) {
        }

        if (!gps_enabled && !network_enabled) {
            // notify user
            showAlert(getString(R.string.locationAlert));
        }

    }

    public class LocationListener implements android.location.LocationListener {

        public LocationListener() {
        }

        public LocationListener(String provider) {
            Log.e(Application.TAG, "LocationListener " + provider);
            mLastLocation = new Location(provider);
        }

        @Override
        public void onLocationChanged(Location location) {
            Log.e(Application.TAG, "onLocationChanged: " + location);

            receivedLocation = true;

            mLastLocation.set(location);

            if (receivedLocation) {
                setMap();
            }
        }

        @Override
        public void onProviderDisabled(String provider) {
            Log.e(Application.TAG, "onProviderDisabled: " + provider);

        }
        @Override
        public void onProviderEnabled(String provider) {
            Log.e(Application.TAG, "onProviderEnabled: " + provider);

        }
        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            Log.e(Application.TAG, "onStatusChanged: " + provider);
        }
    }

    public void requestLocation() {

        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER, 0, 0,
                    mLocationListeners[1]);
        } catch (java.lang.SecurityException ex) {
            Log.i(Application.TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(Application.TAG, "network provider does not exist, " + ex.getMessage());
        }

        try {
            mLocationManager.requestLocationUpdates(
                    LocationManager.GPS_PROVIDER, 0, 0,
                    mLocationListeners[0]);
        } catch (java.lang.SecurityException ex) {
            Log.i(Application.TAG, "fail to request location update, ignore", ex);
        } catch (IllegalArgumentException ex) {
            Log.d(Application.TAG, "gps provider does not exist " + ex.getMessage());
        }
    }
}

出了什么问题？请帮忙..我应该在哪里调用removeUpdates？谢谢..

Answer 1

您注册了 2 个提供商的更新，您是否从这两个提供商处注销了注册？

此外，要使 boolean 标志起作用，您需要进行更改 - 在函数末尾将其设置为 true，并将 if 更改为 if(!receivedLocation) 这将使其生效只运行一次。事实上，它永远不会运行。