C# UTC转换成时间

 public class DateTimeUtil
    {
        private static DateTime utcStartTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
        /// <summary>
        /// 转换为DateTime
        /// </summary>
        /// <param name="timeStamp">10位时间戳（单位：毫秒）</param>
        /// <returns>DateTime</returns>
        public static DateTime TimeStampToDateTime(long timeStamp)
        {
            return utcStartTime.AddMilliseconds(timeStamp).ToLocalTime();
        }

        /// <summary>
        /// DateTime转换为时间戳
        /// </summary>
        /// <param name="dateTime"> DateTime</param>
        /// <returns>10位时间戳（单位：毫秒）</returns>
        public static long DateTimeToTimeStamp(DateTime dateTime)
        {
            return (long)(dateTime.ToUniversalTime() - utcStartTime).TotalMilliseconds;
        }
    }