提供一个获取高精度时间类

如果你觉得用 DotNet 自带的 DateTime 获取的时间精度不够，解决的方法是通过调用 QueryPerformanceFrequency 和 QueryPerformanceCounter这两个API来实现。

        /// <summary>
        /// 获取时间的精度
        /// </summary>
        /// <param name="PerformanceFrequency"></param>
        /// <returns></returns>
        [SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        static private extern bool QueryPerformanceFrequency(ref long PerformanceFrequency);
        /// <summary>
        /// 获取时间计数
        /// </summary>
        /// <param name="PerformanceCount"></param>
        /// <returns></returns>
        [SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        static private extern bool QueryPerformanceCounter(ref long PerformanceCount);

下面是完整的封装代码：

    /// <summary>
    /// 定义一个高精度的时间类
    /// </summary>
    public class Timer
    {
        #region private members
        private long ticksPerSecond = 0;
        private long elapsedTime = 0;
        private long baseTime = 0;
        #endregion

        #region windows API
        /// <summary>
        /// 获取时间的精度
        /// </summary>
        /// <param name="PerformanceFrequency"></param>
        /// <returns></returns>
        [SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        static private extern bool QueryPerformanceFrequency(ref long PerformanceFrequency);
        /// <summary>
        /// 获取时间计数
        /// </summary>
        /// <param name="PerformanceCount"></param>
        /// <returns></returns>
        [SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        static private extern bool QueryPerformanceCounter(ref long PerformanceCount);
        #endregion

        #region constructors
        /// <summary>
        /// new
        /// </summary>
        public Timer()
        {
            // Use QueryPerformanceFrequency to get frequency of the timer
            if (!QueryPerformanceFrequency(ref ticksPerSecond))
                throw new ApplicationException("Timer: Performance Frequency Unavailable");
            Reset();
        }
        #endregion

        #region public methods
        /// <summary>
        /// 重置时间相关计数器
        /// </summary>
        public void Reset()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);
            baseTime = time;
            elapsedTime = 0;
        }
        /// <summary>
        /// 获取当前与最近一次 reset 时间差
        /// </summary>
        /// <returns>The time since last reset.</returns>
        public double GetTime()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);
            return (double)(time - baseTime) / (double)ticksPerSecond;
        }
        /// <summary>
        /// 获取当前系统的时间 ticks 数
        /// </summary>
        /// <returns>The current time in seconds.</returns>
        public double GetAbsoluteTime()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);
            return (double)time / (double)ticksPerSecond;
        }
        /// <summary>
        /// 获取此次与上次调用此方法的两次时间差
        /// </summary>
        /// <returns>The number of seconds since last call of this function.</returns>
        public double GetElapsedTime()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);
            double absoluteTime = (double)(time - elapsedTime) / (double)ticksPerSecond;
            elapsedTime = time;
            return absoluteTime;
        }
        #endregion
    }

调用代码：

            Timer t = new Timer();
            t.GetAbsoluteTime();
            t.GetElapsedTime();
            t.Reset();
            t.GetTime();

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