如何从Android GPS位置获取准确的时间戳

LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

// 获取当前位置
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);

String provider = locationManager.getBestProvider(criteria,
        true); // 获取最佳可用位置提供程序
Location location = locationManager.getLastKnownLocation(provider);

long timestamp = System.currentTimeMillis();

JSONObject json = new JSONObject();

try {
    json.put("latitude", location.getLatitude());
    json.put("longitude", location.getLongitude());
    json.put("timestamp", timestamp);
} catch (JSONException e) {
    e.printStackTrace();
}