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    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();