我在.NET中编写目录扫描器。
对于每个文件/目录,我需要以下信息。
class Info { public bool IsDirectory; public string Path; public DateTime ModifiedDate; public DateTime CreatedDate; }
我有这个功能:
static List<Info> RecursiveMovieFolderScan(string path){ var info = new List<Info>(); var dirInfo = new DirectoryInfo(path); foreach (var dir in dirInfo.GetDirectories()) { info.Add(new Info() { IsDirectory = true, CreatedDate = dir.CreationTimeUtc, ModifiedDate = dir.LastWriteTimeUtc, Path = dir.FullName }); info.AddRange(RecursiveMovieFolderScan(dir.FullName)); } foreach (var file in dirInfo.GetFiles()) { info.Add(new Info() { IsDirectory = false, CreatedDate = file.CreationTimeUtc, ModifiedDate = file.LastWriteTimeUtc, Path = file.FullName }); } return info; }
事实证明这种实现是相当缓慢的。有什么办法可以加快速度吗?我正在考虑使用FindFirstFileW进行手动编码,但是如果有一种内置的方法可以更快地避免这种情况,我想避免这种情况。
需要一点调整的此实现要快5到10倍。
static List<Info> RecursiveScan2(string directory) { IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1); WIN32_FIND_DATAW findData; IntPtr findHandle = INVALID_HANDLE_VALUE; var info = new List<Info>(); try { findHandle = FindFirstFileW(directory + @"\*", out findData); if (findHandle != INVALID_HANDLE_VALUE) { do { if (findData.cFileName == "." || findData.cFileName == "..") continue; string fullpath = directory + (directory.EndsWith("\\") ? "" : "\\") + findData.cFileName; bool isDir = false; if ((findData.dwFileAttributes & FileAttributes.Directory) != 0) { isDir = true; info.AddRange(RecursiveScan2(fullpath)); } info.Add(new Info() { CreatedDate = findData.ftCreationTime.ToDateTime(), ModifiedDate = findData.ftLastWriteTime.ToDateTime(), IsDirectory = isDir, Path = fullpath }); } while (FindNextFile(findHandle, out findData)); } } finally { if (findHandle != INVALID_HANDLE_VALUE) FindClose(findHandle); } return info; }
扩展方法:
public static class FILETIMEExtensions { public static DateTime ToDateTime(this System.Runtime.InteropServices.ComTypes.FILETIME filetime ) { long highBits = filetime.dwHighDateTime; highBits = highBits << 32; return DateTime.FromFileTimeUtc(highBits + (long)filetime.dwLowDateTime); } }
互操作性定义为:
[DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)] public static extern IntPtr FindFirstFileW(string lpFileName, out WIN32_FIND_DATAW lpFindFileData); [DllImport("kernel32.dll", CharSet = CharSet.Unicode)] public static extern bool FindNextFile(IntPtr hFindFile, out WIN32_FIND_DATAW lpFindFileData); [DllImport("kernel32.dll")] public static extern bool FindClose(IntPtr hFindFile); [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct WIN32_FIND_DATAW { public FileAttributes dwFileAttributes; internal System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime; internal System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime; internal System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime; public int nFileSizeHigh; public int nFileSizeLow; public int dwReserved0; public int dwReserved1; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)] public string cFileName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)] public string cAlternateFileName; }