Question

我对Android编程很陌生，所以到目前为止，我的代码是一种非常强大的做事方式。

我有一个片段，将放在几个活动中。该片段只包含一个MapView，并具有以下.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.google.android.gms.maps.MapView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

我现在正在尝试创建一个扩展Fragment的类，并包含这个MapView。片段应放大设备的当前位置。

我正在实施LocationListener，但在locationManager.requestLocationUpdates(bestProvider, 2000, 0, this);行上收到错误，说明该方法无法使用我的MapsFragment类作为参数。
由于我没有Android开发经验，我相信这种方法非常混乱，并且是几个在线教程的合并（似乎没有像样的教程在片段中的MapView上显示当前位置），对我的代码的任何评论，或更合适的方式，将非常感激。

这是我的班级：

import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.Fragment;
import android.support.v4.content.ContextCompat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.MapsInitializer;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MapStyleOptions;

public class MapsFragment extends Fragment implements LocationListener {

    private GoogleApiClient googleApiClient;
    private GoogleMap googleMap;
    private MapView mapView;
    private Location currentLocation;

   public static MapsFragment newInstance() {
       return new MapsFragment();
   }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_map, container, false);

        mapView = (MapView) view.findViewById(R.id.map);
        mapView.onCreate(savedInstanceState);
        mapView.onResume(); // needed to get the map to display immediately

        MapsInitializer.initialize(getActivity().getApplicationContext());

        mapView.getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap gMap) {
                googleMap = gMap;

                if (!checkPermission())
                    askPermission();
                if (checkPermission())
                    googleMap.setMyLocationEnabled(true);
                    zoomToCurrentLocation();
                //else handle no location permissions

            }
        });

        return view;
    }


    private void zoomToCurrentLocation() {
        LocationManager locationManager = (LocationManager) getActivity().getSystemService(getActivity().LOCATION_SERVICE);
        Criteria criteria = new Criteria();
        String bestProvider = locationManager.getBestProvider(criteria, true);
        currentLocation = locationManager.getLastKnownLocation(bestProvider);
        onLocationChanged(currentLocation);
        locationManager.requestLocationUpdates(bestProvider, 2000, 0, this);
    }

    @Override
    public void onLocationChanged(Location location) {
        LatLng currentLatLng = new LatLng(location.getLatitude(), location.getLongitude());
        CameraPosition cameraPosition = new CameraPosition.Builder().target(currentLatLng).zoom(15).build();
        googleMap.animateCamera(CameraUpdateFactory.newCameraPosition((cameraPosition)));

    }

    private boolean checkPermission() {
        return (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED );
    }

    private void askPermission() {
        ActivityCompat.requestPermissions(
                getActivity(),
                new String[] { Manifest.permission.ACCESS_FINE_LOCATION },
                1
        );
    }
}

如果由于上述错误而删除zoomToCurrentLocation()，则一切正常。

修改

这是我尝试过的修订版，但我仍然遇到同样的错误：

private void zoomToCurrentLocation() {
    LocationManager locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    String bestProvider = locationManager.getBestProvider(criteria, true);
    currentLocation = locationManager.getLastKnownLocation(bestProvider);

    LocationListener locationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            if(location != null) {
                LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
                googleMap.animateCamera(CameraUpdateFactory.zoomTo(20));
                googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 20));
            }
        }
    };

    locationManager.requestLocationUpdates(bestProvider, 2000, 0, locationListener);
}

遵循片段中当前位置的MapView

0 个答案: