android - onLocationChanged 不工作，接缝未被调用

Question

我是 android 的新手，我正在做一个必须使用谷歌地图的学校项目。我还必须跟踪用户位置，当位置发生变化时，我必须更新数据库中的用户位置。到目前为止，我设法集成了 gmaps，现在我正在处理位置更改。我在我的类上实现了 LocationListener 接口(interface)，我还覆盖了 onLocationChanged 方法，该方法无法正常工作。我缺少什么？谢谢你!

public class MapFragment extends Fragment implements LocationListener, DialogManager.OnDialogListener {

private GoogleMap gMap;
private SupportMapFragment smf;
private View v;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    v = inflater.inflate(R.layout.activity_main, container, false);
    return v;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    FragmentManager fm = getChildFragmentManager();
    smf = (SupportMapFragment) fm.findFragmentById(R.id.mainContent);
    if (smf == null) {
        smf = SupportMapFragment.newInstance();
        fm.beginTransaction().replace(R.id.mainContent, smf).commit();
    }
}

@Override
public void onResume() {
    super.onResume();
    if(!LocationUtils.getInstance().isGPSON(this.getActivity())) {
        DialogManager.buildAlertMessageNoGps(this.getActivity(), this);
    } else {
        if(smf!=null) {
            gMap = smf.getMap();
            if(gMap != null) {
                setUpMap();
            }
        }
    }
}

private void setUpMap() {
    Location location = LocationUtils.getInstance().getLastKnownLocation(this.getActivity());
    LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());

    gMap.setMyLocationEnabled(true);
    gMap.animateCamera(CameraUpdateFactory.zoomTo(20));
    gMap.addMarker(new MarkerOptions().position(latLng).title("I am here!")); //this works, but it put  the market on the last known location, not where is my current gps location ..
    gMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 20));

    List <Address> adr = LocationUtils.getInstance().getAddress(latLng, this.getActivity());
    String str = adr.get(0).getAddressLine(0);
    String city   = adr.get(0).getAddressLine(1);
    String coutry= adr.get(0).getAddressLine(2);

    Toast.makeText(getActivity().getApplicationContext(),"str: "+ str+"\ncity: "+city+"\ncountry: "+country, Toast.LENGTH_LONG).show();
}

@Override
public void onLocationChanged(Location location) {
    Toast.makeText(getActivity().getApplicationContext(),"sssCHANGEDsss", Toast.LENGTH_LONG).show();  //this never appear
    if(gMap != null) {
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        gMap.animateCamera(CameraUpdateFactory.zoomTo(20));
        gMap.addMarker(new MarkerOptions().position(latLng).title("updated!")); //marker title never updates
        gMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 20));
    }
}

@Override
    public void onButtonClicked(int which) {
        switch (which) {
            case DialogManager.BUTTON_POSITIVE:
                startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                break;
        }
    }
}

Answer 1

您必须调用 requestLocationUpdates 来获取位置更新。在您的设置 map 函数中将其与其他函数一起使用。

LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    LocationListener locationListener = new LocationListener() {

    @Override
    public void onLocationChanged(Location arg0) {
        Toast.makeText(getActivity().getApplicationContext(),"sssCHANGEDsss", Toast.LENGTH_LONG).show();  //this never appear
    if(location != null) {
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        gMap.animateCamera(CameraUpdateFactory.zoomTo(20));
        gMap.addMarker(new MarkerOptions().position(latLng).title("updated!")); //marker title never updates
        gMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 20));
    }

    }
};
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 1.0f, locationListener);

更新:我刚刚注意到您也在为您的 Activity 实现 LocationListerner。如果您打算使用上述解决方案，则无需为 Activity 实现 LocationListener。从更广泛的角度来看，尤其是当您需要通过应用程序更新位置时，创建一个自定义位置监听器类。从 Activity 中解脱出来并明智地使用。

并且不要忘记将 ACCESS_COARSE_LOCATION 或 ACCESS_FINE_LOCATION 权限添加到您的 AndoidManifest.xml。