public static String getDeviceSerial() {
  String serial = "unknown";
  try {
   Class clazz = Class.forName("android.os.Build");
   Class paraTypes = Class.forName("java.lang.String");
   Method method = clazz.getDeclaredMethod("getString", paraTypes);
   if (!method.isAccessible()) {
    method.setAccessible(true);
   }
   serial = (String)method.invoke(new Build(), "ro.serialno");
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  } catch (NoSuchMethodException e) {
   e.printStackTrace();
  } catch (InvocationTargetException e) {
   e.printStackTrace();
  } catch (IllegalAccessException e) {
   e.printStackTrace();
  }
  return serial;
}