可能更快的替代方法是使用 WINAPI FindNextFile。有一个很好的Faster Directory Enumeration Tool。可以这样使用：
HashSet<FileData> GetPast60(string dir)
{
DateTime retval = DateTime.Now.AddDays(-60);
HashSet<FileData> oldFiles = new HashSet<FileData>();
FileData [] files = FastDirectoryEnumerator.GetFiles(dir);
for (int i=0; i<files.Length; i++)
{
if (files[i].LastWriteTime < retval)
{
oldFiles.Add(files[i]);
}
}
return oldFiles;
}
编辑
因此，基于下面的 cmets，我决定对这里的建议解决方案以及我能想到的其他解决方案进行基准测试。有趣的是，EnumerateFiles 似乎优于 FindNextFile in C#，而 EnumerateFiles 和 AsParallel 是迄今为止最快的，令人惊讶的是命令提示符计数。但是请注意，AsParallel 没有获得完整的文件计数，或者丢失了其他文件计数的一些文件，因此您可以说命令提示符方法是最好的。
适用配置：
- Windows 7 Service Pack 1 x64
- Intel(R) Core(TM) i5-3210M CPU @2.50GHz 2.50GHz
- 内存：6GB
- 平台目标：x64
- 无优化（注意：使用优化编译会导致性能极差）
- 允许不安全的代码
- 不调试就开始
以下是三张截图：
我在下面包含了我的测试代码：
static void Main(string[] args)
{
Console.Title = "File Enumeration Performance Comparison";
Stopwatch watch = new Stopwatch();
watch.Start();
var allfiles = GetPast60("C:\\Users\\UserName\\Documents");
watch.Stop();
Console.WriteLine("Total time to enumerate using WINAPI =" + watch.ElapsedMilliseconds + "ms.");
Console.WriteLine("File Count: " + allfiles);
Stopwatch watch1 = new Stopwatch();
watch1.Start();
var allfiles1 = GetPast60Enum("C:\\Users\\UserName\\Documents\\");
watch1.Stop();
Console.WriteLine("Total time to enumerate using EnumerateFiles =" + watch1.ElapsedMilliseconds + "ms.");
Console.WriteLine("File Count: " + allfiles1);
Stopwatch watch2 = new Stopwatch();
watch2.Start();
var allfiles2 = Get1("C:\\Users\\UserName\\Documents\\");
watch2.Stop();
Console.WriteLine("Total time to enumerate using Get1 =" + watch2.ElapsedMilliseconds + "ms.");
Console.WriteLine("File Count: " + allfiles2);
Stopwatch watch3 = new Stopwatch();
watch3.Start();
var allfiles3 = Get2("C:\\Users\\UserName\\Documents\\");
watch3.Stop();
Console.WriteLine("Total time to enumerate using Get2 =" + watch3.ElapsedMilliseconds + "ms.");
Console.WriteLine("File Count: " + allfiles3);
Stopwatch watch4 = new Stopwatch();
watch4.Start();
var allfiles4 = RunCommand(@"dir /a: /b /s C:\Users\UserName\Documents");
watch4.Stop();
Console.WriteLine("Total time to enumerate using Command Prompt =" + watch4.ElapsedMilliseconds + "ms.");
Console.WriteLine("File Count: " + allfiles4);
Console.WriteLine("Press Any Key to Continue...");
Console.ReadLine();
}
private static int RunCommand(string command)
{
var process = new Process()
{
StartInfo = new ProcessStartInfo("cmd")
{
UseShellExecute = false,
RedirectStandardInput = true,
RedirectStandardOutput = true,
CreateNoWindow = true,
Arguments = String.Format("/c \"{0}\"", command),
}
};
int count = 0;
process.OutputDataReceived += delegate { count++; };
process.Start();
process.BeginOutputReadLine();
process.WaitForExit();
return count;
}
static int GetPast60Enum(string dir)
{
return new DirectoryInfo(dir).EnumerateFiles("*.*", SearchOption.AllDirectories).Count();
}
private static int Get2(string myBaseDirectory)
{
DirectoryInfo dirInfo = new DirectoryInfo(myBaseDirectory);
return dirInfo.EnumerateFiles("*.*", SearchOption.AllDirectories)
.AsParallel().Count();
}
private static int Get1(string myBaseDirectory)
{
DirectoryInfo dirInfo = new DirectoryInfo(myBaseDirectory);
return dirInfo.EnumerateDirectories()
.AsParallel()
.SelectMany(di => di.EnumerateFiles("*.*", SearchOption.AllDirectories))
.Count() + dirInfo.EnumerateFiles("*.*", SearchOption.TopDirectoryOnly).Count();
}
private static int GetPast60(string dir)
{
return FastDirectoryEnumerator.GetFiles(dir, "*.*", SearchOption.AllDirectories).Length;
}
注意：我专注于基准未修改日期的计数。