HarmonyOS 如何实现时间戳转成yyyy-mm-dd的格式

参考代码：

public static String UTCTimeToString(int utc) {
  if (utc != 0) {
    SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    Calendar cal = Calendar.getInstance();
    long a = 1000;
    cal.setTimeInMillis(utc * a);
    long time = cal.getTimeInMillis();
    Date date2 = new Date(time);
    return fmt.format(date2);
  }
  return "未知";
}