using System;
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namespace Sodao.FastSocket.SocketBase.Utils
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{
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/// <summary>
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/// 关于时间的一些操作
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/// </summary>
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static public class Date
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{
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#region Private Members
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static private int lastTicks = -1;
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static private DateTime lastDateTime;
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/// <summary>
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/// unix下的纪元时间
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/// </summary>
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static private readonly DateTime unixEpoch =
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new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
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/// <summary>
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/// the max milliseconds since epoch.
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/// </summary>
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static private readonly long dateTimeMaxValueMillisecondsSinceEpoch =
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(DateTime.MaxValue - unixEpoch).Ticks / 10000;
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#endregion
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#region Public Methods
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/// <summary>
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/// Gets the current utc time in an optimized fashion.
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/// </summary>
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static public DateTime UtcNow
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{
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get
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{
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int tickCount = Environment.TickCount;
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if (tickCount == lastTicks) return lastDateTime;
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DateTime dt = DateTime.UtcNow;
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lastTicks = tickCount;
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lastDateTime = dt;
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return dt;
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}
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}
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/// <summary>
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/// Converts a DateTime to UTC (with special handling for MinValue and MaxValue).
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/// </summary>
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/// <param name="dateTime">A DateTime.</param>
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/// <returns>The DateTime in UTC.</returns>
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public static DateTime ToUniversalTime(DateTime dateTime)
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{
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if (dateTime.Kind == DateTimeKind.Utc) return dateTime;
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else
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{
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if (dateTime == DateTime.MinValue) return DateTime.SpecifyKind(DateTime.MinValue, DateTimeKind.Utc);
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else if (dateTime == DateTime.MaxValue) return DateTime.SpecifyKind(DateTime.MaxValue, DateTimeKind.Utc);
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else return dateTime.ToUniversalTime();
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}
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}
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/// <summary>
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/// Converts a DateTime to number of milliseconds since Unix epoch.
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/// </summary>
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/// <param name="dateTime">A DateTime.</param>
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/// <returns>Number of seconds since Unix epoch.</returns>
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public static long ToMillisecondsSinceEpoch(DateTime dateTime)
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{
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return (ToUniversalTime(dateTime) - unixEpoch).Ticks / 10000;
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}
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/// <summary>
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/// Converts a DateTime to number of seconds since Unix epoch.
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/// </summary>
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/// <param name="dateTime">A DateTime.</param>
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/// <returns>Number of seconds since Unix epoch.</returns>
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public static long ToSecondsSinceEpoch(DateTime dateTime)
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{
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return ToMillisecondsSinceEpoch(dateTime) / 1000;
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}
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/// <summary>
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/// Converts from number of milliseconds since Unix epoch to DateTime.
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/// </summary>
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/// <param name="millisecondsSinceEpoch">The number of milliseconds since Unix epoch.</param>
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/// <returns>A DateTime.</returns>
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public static DateTime ToDateTimeFromMillisecondsSinceEpoch(long millisecondsSinceEpoch)
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{
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// MaxValue has to be handled specially to avoid rounding errors
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if (millisecondsSinceEpoch == dateTimeMaxValueMillisecondsSinceEpoch)
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return DateTime.SpecifyKind(DateTime.MaxValue, DateTimeKind.Utc);
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else return unixEpoch.AddTicks(millisecondsSinceEpoch * 10000);
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}
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/// <summary>
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/// Converts from number of seconds since Unix epoch to DateTime.
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/// </summary>
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/// <param name="secondsSinceEpoch">The number of seconds since Unix epoch.</param>
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/// <returns>A DateTime.</returns>
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public static DateTime ToDateTimeFromSecondsSinceEpoch(long secondsSinceEpoch)
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{
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return ToDateTimeFromMillisecondsSinceEpoch(secondsSinceEpoch * 1000);
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}
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/// <summary>
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/// Converts a DateTime to local time (with special handling for MinValue and MaxValue).
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/// </summary>
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/// <param name="dateTime">A DateTime.</param>
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/// <param name="kind">A DateTimeKind.</param>
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/// <returns>The DateTime in local time.</returns>
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public static DateTime ToLocalTime(DateTime dateTime, DateTimeKind kind)
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{
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if (dateTime.Kind == kind) return dateTime;
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else
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{
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if (dateTime == DateTime.MinValue) return DateTime.SpecifyKind(DateTime.MinValue, kind);
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else if (dateTime == DateTime.MaxValue) return DateTime.SpecifyKind(DateTime.MaxValue, kind);
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else return DateTime.SpecifyKind(dateTime.ToLocalTime(), kind);
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}
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}
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/// <summary>
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/// SpecifyKind
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/// </summary>
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/// <param name="dt"></param>
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/// <param name="kind"></param>
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/// <returns></returns>
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public static DateTime SpecifyKind(DateTime dt, DateTimeKind kind)
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{
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if (dt.Kind == kind) return dt;
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return DateTime.SpecifyKind(dt, kind);
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}
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#endregion
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}
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}
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