根据当前和某个位置之间的距离更改 LocationRequest 的间隔

Question

我想通过使用 Fused Location API 更改更新间隔来节省电量。距离某个位置越远，间隔就应该越大。

public class service extends Service implements GooglePlayServicesClient.ConnectionCallbacks,GooglePlayServicesClient.OnConnectionFailedListener,LocationListener {
    private LocationRequest locationrequest;
    private LocationClient locationclient;



    @Override
    public void onCreate() {

        int resp = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (resp == ConnectionResult.SUCCESS) {
            locationclient = new LocationClient(this, this, this);
            locationclient.connect();
        } else {
            Toast.makeText(this, "Google Play Service Error " + resp, Toast.LENGTH_LONG).show();

        }

    }



    @Override
    public void onDestroy() {
        super.onDestroy();
        if(locationclient!=null)
            locationclient.disconnect();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onConnected(Bundle connectionHint) {
        Log.i(TAG, "onConnected");
        if (locationclient != null && locationclient.isConnected()) {
            locationrequest = LocationRequest.create();
            locationrequest.setInterval(5000);
            locationrequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
            locationclient.requestLocationUpdates(locationrequest, this);

        }
    }

    @Override
    public void onDisconnected() {
        Log.i(TAG, "onDisconnected");


    }

    @Override
    public void onConnectionFailed(ConnectionResult result) {
        Log.i(TAG, "onConnectionFailed");


    }

    @Override
    public void onLocationChanged(Location location) {
        if(location!=null){
            double Lat=-34.922611;
            double Lng = 138.596161;
            Location Loc = new Location("");
            Loc.setLatitude(Lat);
            Loc.setLongitude(Lng);
            Float dist=location.distanceTo(Loc);
            String distance = Float.toString(dist);
            if (dist>100){
                Log.i("distance",distance);
                locationclient.removeLocationUpdates(this);
                locationrequest.setInterval(30000);
                locationrequest.setPriority(LocationRequest.PRIORITY_LOW_POWER);
                locationclient.requestLocationUpdates(locationrequest, this);

            }

            Log.i(TAG, "Location Request :" + location.getLatitude() + "," + location.getLongitude());


        }

    }
}

不幸的是，这不起作用......有人知道为什么吗？或者有更好的方法吗？谢谢

编辑1：我得到的输出是一个位置请求，其行为与更改之前相同。如果我调用 locationrequest.getInterval ，将显示新的间隔，但 locationrequest 将为我提供第一个间隔的更新。

Answer 1

使用 Fused Location API，您可以执行以下操作：

mLocationRequest = LocationRequest.create()
                    .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                    .setInterval(INTERVAL)        
                    .setFastestInterval(FASTEST_INTERVAL); 

然后，当您的应用程序中触发事件并且您想要更改间隔时，您将调用同一段代码，但只需更改INTERVAL和FASTEST_INTERVAL值。更改它们后，请不要忘记更新位置更新，如下所示：

LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);