C# DateTime与时间戳转换

/// <summary>
/// DateTime转时间戳
/// </summary>
/// <param name="dateTime"></param>
/// <returns></returns>
public static long GetTimeStamp(DateTime dateTime)
{
    // 开始时间
    DateTime startTime = new(1970, 1, 1, 8, 0, 0);
    // 10位的时间戳
    long timeStamp = Convert.ToInt64(dateTime.Subtract(startTime).TotalSeconds);
    // 13位的时间戳
    //long timeStamp = Convert.ToInt64(dateTime.Subtract(_dtStart).TotalMilliseconds);
    return timeStamp;
}
/// <summary>
/// 时间戳转DateTime
/// </summary>
/// <param name="timeStamp"></param>
/// <returns></returns>
public static DateTime GetDateTime(long timeStamp)
{
    // 开始时间
    DateTime startTime = TimeZoneInfo.ConvertTime(new DateTime(1970, 1, 1), TimeZoneInfo.Local);
    long lTime = long.Parse(timeStamp + "0000000");
    return startTime.Add(new TimeSpan(lTime)).AddHours(8);
}