java - 尝试通过 onConnected() 方法获取当前位置

Question

我正在尝试通过 onConnected() 方法获取我的当前位置。但不幸的是 onMapReady() 被提前调用。因此，我的变量 currentLatitude 和 currentLongitude 包含值 0.0，如您在下面的日志中看到的:

I/System.out: currentLatitude : 0.0
I/System.out: currentLongitude : 0.0
D/: HostConnection::get() New Host Connection established 0xeec39820, tid 23599
I/System.out: onConnected

我已经尝试使用 AsyncTask 但这不起作用，因为 onPreExecute() 在 onConnected() 之前执行。您可以在这里看到它的屏幕截图:

链接:/image/kU9sK.png

您可以在下面看到我的代码:

public class BreakDownOnMaps extends FragmentActivity implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener,
        OnMapReadyCallback {
    protected GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest =  new LocationRequest();
    double currentLatitude;
    double currentLongitude;
    LatLng latLng;

    @TargetApi(Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_break_down_on_maps);
        buildApi();
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    protected void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }

    @Override
    protected void onResume() {
        super.onResume();
        mGoogleApiClient.connect();
    }

    private void buildApi() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

    public void handleNewLocation(Location loc) {
        currentLatitude = loc.getLatitude();
        currentLongitude = loc.getLongitude();
        latLng = new LatLng(currentLatitude, currentLongitude);
        System.out.println("handleNewLocation ");
    }

    @Override
    public void onConnected(Bundle bundle) {
        System.out.println("onConnected");
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        }
        Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (location == null) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, (com.google.android.gms.location.LocationListener) this);
        }
        else {
            handleNewLocation(location);
        }
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        System.out.println("currentLatitude : " + currentLatitude);
        System.out.println("currentLongitude : " + currentLongitude);
        latLng = new LatLng(currentLatitude, currentLongitude);
        MarkerOptions options = new MarkerOptions()
                .position(latLng)
                .title("I am here!");
        googleMap.addMarker(options);
        googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    }

Answer 1

我通过使用名为 gMap 的全局 GoogleMap 变量的 setter 方法修复了该问题。在 handleNewLocation() 内部，我使用变量 gMap 通过标记来确定我所在的位置。

完整代码如下:

public class BreakDownOnMaps extends FragmentActivity implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener,
        OnMapReadyCallback {
    protected GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest =  new LocationRequest();
    double currentLatitude;
    double currentLongitude;
    LatLng latLng;
    GoogleMap gMap;


    @TargetApi(Build.VERSION_CODES.M)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_break_down_on_maps);
        buildApi();
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    protected void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }
    @Override
    protected void onResume() {
        super.onResume();
        mGoogleApiClient.connect();
    }

    private void buildApi() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

    public void handleNewLocation(Location loc) {
        currentLatitude = loc.getLatitude();
        currentLongitude = loc.getLongitude();
        latLng = new LatLng(currentLatitude, currentLongitude);
        System.out.println("handleNewLocation ");
        MarkerOptions options = new MarkerOptions()
                .position(latLng)
                .title("I am here!");
        gMap.addMarker(options);
        gMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    }

    @Override
    public void onConnected(Bundle bundle) {
        System.out.println("onConnected");
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        }
        Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (location == null) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, (com.google.android.gms.location.LocationListener) this);
        }
        else {
            handleNewLocation(location);
        };
    }

    @Override
    public void onConnectionSuspended(int i) {}

    @Override
    public void onLocationChanged(Location location) {
        handleNewLocation(location);
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {}

    @Override
    public void onMapReady(GoogleMap googleMap) {
        System.out.println("currentLatitude : " + currentLatitude);
        System.out.println("currentLongitude : " + currentLongitude);
        latLng = new LatLng(currentLatitude, currentLongitude);
        setgMap(googleMap);
        if(currentLatitude != 0 || currentLongitude != 0) {
            MarkerOptions options = new MarkerOptions()
                    .position(latLng)
                    .title("I am here!");
            googleMap.addMarker(options);
            googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        }
    }

    public GoogleMap getgMap() {
        return gMap;
    }

    public void setgMap(GoogleMap gMap) {
        this.gMap = gMap;
    }
}