Google glass-GDK 应用程序 getSpeed() 返回 0.0

Question

我正在尝试在 google glass live card 上显示用户的速度。 我能够得到纬度和经度，但 getSpeed() 总是返回 0.0。我已经检查了关于 SO 的类似问题，但没有任何帮助。

这是我的代码

        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        LocationManager mLocationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        String provider = mLocationManager.getBestProvider(criteria, true);
        boolean isEnabled = mLocationManager.isProviderEnabled(provider);
        if (isEnabled) {
        // Define a listener that responds to location updates
        LocationListener locationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
        // Called when a new location is found by the network location provider.
        if (location != null) {
        Geocoder geocoder = new Geocoder(Start_service.this.getBaseContext(), Locale.getDefault());
        // lat,lng, your current location
        List<Address> addresses = null;
        try {
            lati= location.getLatitude();
            longi=location.getLongitude();
            speed=location.getSpeed();
        addresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);
        }
        catch (IOException e) {
        System.out.println(e);
        e.printStackTrace();
        }

Answer 1

Location providers don't guarantee to provide the speed value. 你只能从调用 setSpeed 的提供者那里得到速度。您可以设置 Criteria 变量来指示您需要速度值。

Criteria criteria = new Criteria();
criteria.setSpeedRequired(true);

或者您可以考虑自己计算。见why getSpeed() always return 0 on android。

另外，使用 hasSpeed() 检查速度是否可用。