DateTime 转 Unix 时间戳

DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
int unixTimeSpan = (int)(time - startTime).TotalSeconds;

Unix 时间戳转 DateTime

DateTime dateTimeStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1));
long longTime = long.Parse(timeStamp + "0000000");
TimeSpan toNow = new TimeSpan(longTime);
DateTime dateTime = dateTimeStart.Add(toNow);