Question

用C#做一个毫秒级别的定时器，能准群的实现每40MS调用一个函数？

c#自带的只有55ms的精确度，要想实现准确的，听说需要调用windows API的函数，但我没用过windowsAPI，希望各位能给介绍下。现在发现.net越来越不好，需要其他的帮忙，想运行还得有它的环境

Answer 1

哈哈 尺有所短啊

我用的一个

public class Counter
{
long elapsedCount = 0;
long startCount = 0;

/// <summary>
/// Start timing
/// </summary>
public void Start()
{
startCount = 0;
QueryPerformanceCounter(ref startCount);
}

/// <summary>
/// Stop timing
/// </summary>
public void Stop()
{
long stopCount = 0;
QueryPerformanceCounter(ref stopCount);

elapsedCount += (stopCount - startCount);
}

/// <summary>
/// Clear the timer
/// </summary>
public void Clear()
{
elapsedCount = 0;
}

/// <summary>
/// The elapsed time measured in seconds.
/// </summary>
public float Seconds
{
get
{
long freq = 0;
QueryPerformanceFrequency(ref freq);
return ((float)elapsedCount / (float)freq);
}
}

/// <summary>
/// The elapsed time measured in milliseconds.
/// </summary>
public float Milliseconds
{
get
{
return Seconds * 1000;
}
}

/// <summary>
/// Convert to a string
/// </summary>
/// <returns>The current elapsed time in seconds</returns>
public override string ToString()
{
return String.Format("{0} seconds", Seconds);
}

static long Frequency
{
get
{
long freq = 0;
QueryPerformanceFrequency(ref freq);
return freq;
}
}

static long Value
{
get
{
long count = 0;
QueryPerformanceCounter(ref count);
return count;
}
}

[System.Runtime.InteropServices.DllImport("KERNEL32")]
private static extern bool QueryPerformanceCounter(ref long
lpPerformanceCount);

[System.Runtime.InteropServices.DllImport("KERNEL32")]
private static extern bool QueryPerformanceFrequency(ref long
lpFrequency);
}

Answer 2

如果我没记错的话，在System.Thread命名空间下的有一个定时器类，类名叫Timer（注意不要和另一个命名空间下的Timer混淆），里面可以设置毫秒级定时操作。你可以找相关的帮助看看。

在很多.net开始的企业级应用windows服务中，常用到这个类做定时任务。

Answer 3

使用StopWatch类
不用native API