用戶位置未顯示在地圖上

Question

我正在使用本教程開發基於GPS /用戶位置的應用程序。 這個想法是，當用戶打開第二個活動（通過單擊按鈕）時，它應該在地圖上找到該設備並每秒更新一次，這是活動代碼：

public class MapLocation extends AppCompatActivity implements
    OnMapReadyCallback,
    GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener,
    LocationListener {

GoogleMap mGoogleMap;
GoogleApiClient mGoogleApiClient;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.maplocation);
    initMap();
}

private void initMap() {
    MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.mapFragment);
    mapFragment.getMapAsync(this);
}

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

    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addApi(LocationServices.API)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .build();
    mGoogleApiClient.connect();
}

LocationRequest mLocationRequest;

@Override
public void onConnected(Bundle bundle) {
    mLocationRequest = LocationRequest.create();
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setInterval(1000);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (checkSelfPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    public void requestPermissions(@NonNull String[] permissions, int requestCode)
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for Activity#requestPermissions for more details.
            return;
        }
    }
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}

@Override
public void onConnectionSuspended(int i) {

}

@Override
public void onConnectionFailed(ConnectionResult connectionResult) {

}

@Override
public void onLocationChanged(Location location) {
    if(location == null) {
        Toast.makeText(this, "Can't get current location!", Toast.LENGTH_LONG).show();
    } else {
        LatLng ll = new LatLng(location.getLatitude(), location.getLongitude());
        CameraUpdate update = CameraUpdateFactory.newLatLngZoom(ll, 15);
        mGoogleMap.animateCamera(update);
    }
}}

這是xml代碼：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@color/_fff">

    <fragment
        android:id="@+id/mapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name="com.google.android.gms.maps.MapFragment" />
</LinearLayout>

這是必要的權限：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

該地圖可以正常工作，但是問題在於它不會在本教程中的地圖上顯示我的設備（我的位置）。 我在設備和仿真器上運行應用程序，結果相同，地圖運行正常，但我的位置未顯示在地圖上。 有人可以向我解釋我在做什么錯嗎？

Answer 1

您可以立即看到的一個關鍵錯誤是您缺少setLocationEnabbled(true)方法。

試試這個代碼：

@Override
public void onMapReady(GoogleMap googleMap) {
    Toast.makeText(this, "onMapReady", Toast.LENGTH_LONG).show();
    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
            && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    } else {
        mMap = googleMap;
        buildGoogleApiClient();
        mMap.setMyLocationEnabled(true); 
        googleMap.getUiSettings().setZoomControlsEnabled(true);
    }
}

 @Override
public void onConnected(@Nullable Bundle bundle) {
    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        Toast.makeText(this, "Location is disabled, turn it on in your settings,", Toast.LENGTH_LONG).show();
    } else {
        Toast.makeText(this, "onConnected", Toast.LENGTH_LONG).show();
        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
                mGoogleApiClient);
        if (mLastLocation != null) {
            //place marker at current position
            mMap.clear();
            double latitude = mLastLocation.getLatitude();
            double longitude = mLastLocation.getLongitude();
            LatLng latLng = new LatLng(latitude, longitude);
            MarkerOptions markerOptions = new MarkerOptions();
            markerOptions.position(latLng);
            markerOptions.title("Current Position");
            markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_VIOLET));
            mCurrLocation = mMap.addMarker(markerOptions);
            CameraPosition cameraPosition = new CameraPosition.Builder()
                    .target(new LatLng(latitude, longitude))
                    .zoom(11)
                    .build();
            mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
        }else{
             Toast.makeText(this, "LastLocation is null", Toast.LENGTH_LONG).show();}

希望能幫助到你 ：）