如何：枚举目录和文件
从 .NET Framework 4 版开始，可以通过使用一些方法来枚举目录和文件，这些方法返回一个目录和文件的名称字符串的可枚举集合。 也可以使用将返回 DirectoryInfo、FileInfo 或 FileSystemInfo 对象的可枚举集合的方法。 在 .NET Framework 的早期版本中，只能获取这些集合的数组。与数组相比，可枚举的集合可提供更好的性能。
此外，还可以使用通过上述方法获得的可枚举集合为集合类（如 List<T> 类）的构造函数提供 IEnumerable<T> 参数。
如果只需要获取目录或文件的名称，请使用 Directory 类的枚举方法。 如果需要获取目录或文件的其他属性，请使用 DirectoryInfo 和 FileSystemInfo 类。 也可以枚举文本文件的各个行。
下表提供了返回可枚举集合的方法的指南。
要枚举的项 |
要返回的可枚举集合 |
要使用的方法 |
|---|---|---|
目录 |
目录名称。 |
|
目录信息 (DirectoryInfo)。 |
||
文件 |
文件名称。 |
|
文件信息 (FileInfo)。 |
||
文件系统信息 |
文件系统项。 |
|
文件系统信息 (FileSystemInfo)。 |
||
文本文件中的行 |
文件中的行。 |
虽然可以使用 AllDirectories 选项立即枚举父目录的子目录中的所有文件，但未经授权的访问异常 (UnauthorizedAccessException) 可能会导致枚举无法完成。 如果可能出现这些异常，则可以捕获它们并继续操作，采用的方式是先枚举目录，然后再枚举文件。
如果您运行的是 Windows XP 或早期版本，并且如果有一个打开句柄保持在其中一个枚举的目录或文件中，则对遵循枚举的文件或目录执行删除操作可能会失败。 如果出现这种情况，必须包括垃圾回收以移除打开句柄。
枚举目录名称
使用 Directory.EnumerateDirectories(String) 方法可按指定路径获取顶级目录名称的列表。
Imports System.Collections.Generic Imports System.IO Imports System.Linq Module Module1 Sub Main() Try Dim dirPath As String = "\\archives\2009\reports" ' LINQ query. Dim dirs = From folder In _ Directory.EnumerateDirectories(dirPath) For Each folder In dirs ' Remove path information from string. Console.WriteLine("{0}", _ folder.Substring(folder.LastIndexOf("\") + 1)) Next Console.WriteLine("{0} directories found.", _ dirs.Count.ToString()) ' Optionally create a List collection. Dim workDirs As List(Of String) = New List(Of String)(dirs) Catch UAEx As UnauthorizedAccessException Console.WriteLine(UAEx.Message) Catch PathEx As PathTooLongException Console.WriteLine(PathEx.Message) End Try End Sub End Moduleusing System; using System.Collections.Generic; using System.IO; using System.Linq; class Program { private static void Main(string[] args) { try { string dirPath = @"\\archives\2009\reports"; // LINQ query. var dirs = from dir in Directory.EnumerateDirectories(dirPath) select dir; // Show results. foreach (var dir in dirs) { // Remove path information from string. Console.WriteLine("{0}", dir.Substring(dir.LastIndexOf("\\") + 1)); } Console.WriteLine("{0} directories found.", dirs.Count<string>().ToString()); // Optionally create a List collection. List<string> workDirs = new List<string>(dirs); } catch (UnauthorizedAccessException UAEx) { Console.WriteLine(UAEx.Message); } catch (PathTooLongException PathEx) { Console.WriteLine(PathEx.Message); } } }
枚举所有目录中的文件名称
使用 Directory.EnumerateFiles(String, String, SearchOption) 方法可搜索所有目录以按指定路径获取与指定搜索模式匹配的文件名称的列表。
Imports System.IO Imports System.Xml.Linq Module Module1 Sub Main() Try Dim files = From chkFile In Directory.EnumerateFiles("c:\", "*.txt", _ SearchOption.AllDirectories) From line In File.ReadLines(chkFile) Where line.Contains("Microsoft") Select New With {.curFile = chkFile, .curLine = line} For Each f In files Console.WriteLine("{0}\t{1}", f.curFile, f.curLine) Next Console.WriteLine("{0} files found.", _ files.Count.ToString()) Catch UAEx As UnauthorizedAccessException Console.WriteLine(UAEx.Message) Catch PathEx As PathTooLongException Console.WriteLine(PathEx.Message) End Try End Sub End Moduleusing System; using System.IO; using System.Linq; class Program { static void Main(string[] args) { try { var files = from file in Directory.EnumerateFiles(@"c:\", "*.txt", SearchOption.AllDirectories) from line in File.ReadLines(file) where line.Contains("Microsoft") select new { File = file, Line = line }; foreach (var f in files) { Console.WriteLine("{0}\t{1}", f.File, f.Line); } Console.WriteLine("{0} files found.", files.Count().ToString()); } catch (UnauthorizedAccessException UAEx) { Console.WriteLine(UAEx.Message); } catch (PathTooLongException PathEx) { Console.WriteLine(PathEx.Message); } } }
枚举 DirectoryInfo 对象的集合
使用 DirectoryInfo.EnumerateDirectories 方法可获取顶级目录的集合。
' Create a DirectoryInfo of the Program Files directory. Dim dirPrograms As New DirectoryInfo("c:\program files") Dim StartOf2009 As New DateTime(2009, 1, 1) ' LINQ query for all directories created before 2009. Dim dirs = From dir In dirPrograms.EnumerateDirectories() Where dir.CreationTimeUtc < StartOf2009 ' Show results. For Each di As DirectoryInfo In dirs Console.WriteLine("{0}", di.Name) Next// Create a DirectoryInfo of the Program Files directory. DirectoryInfo dirPrograms = new DirectoryInfo(@"c:\program files"); DateTime StartOf2009 = new DateTime(2009, 01, 01); // LINQ query for all directories created before 2009. var dirs = from dir in dirPrograms.EnumerateDirectories() where dir.CreationTimeUtc < StartOf2009 select new { ProgDir = dir, }; // Show results. foreach (var di in dirs) { Console.WriteLine("{0}", di.ProgDir.Name); }
枚举所有目录中的 FileInfo 对象的集合
使用 DirectoryInfo.EnumerateFiles 方法可获取所有目录中与指定搜索模式匹配的文件的集合。 本示例先枚举顶级目录以捕获可能出现的未经授权的访问异常，然后再枚举文件。
Imports System Imports System.IO Class Program Public Shared Sub Main(ByVal args As String()) ' Create a DirectoryInfo object of the starting directory. Dim diTop As New DirectoryInfo("d:\") Try ' Enumerate the files just in the top directory. For Each fi In diTop.EnumerateFiles() Try ' Display each file over 10 MB; If fi.Length > 10000000 Then Console.WriteLine("{0}" & vbTab & vbTab & "{1}", fi.FullName, fi.Length.ToString("N0")) End If ' Catch unauthorized access to a file. Catch UnAuthTop As UnauthorizedAccessException Console.WriteLine("{0}", UnAuthTop.Message) End Try Next ' Enumerate all subdirectories. For Each di In diTop.EnumerateDirectories("*") Try ' Enumerate each file in each subdirectory. For Each fi In di.EnumerateFiles("*", SearchOption.AllDirectories) Try ' // Display each file over 10 MB; If fi.Length > 10000000 Then Console.WriteLine("{0}" & vbTab & vbTab & "{1}", fi.FullName, fi.Length.ToString("N0")) End If ' Catch unauthorized access to a file. Catch UnAuthFile As UnauthorizedAccessException Console.WriteLine("UnAuthFile: {0}", UnAuthFile.Message) End Try Next ' Catch unauthorized access to a subdirectory. Catch UnAuthSubDir As UnauthorizedAccessException Console.WriteLine("UnAuthSubDir: {0}", UnAuthSubDir.Message) End Try Next ' Catch error in directory path. Catch DirNotFound As DirectoryNotFoundException Console.WriteLine("{0}", DirNotFound.Message) ' Catch unauthorized access to a first tier directory. Catch UnAuthDir As UnauthorizedAccessException Console.WriteLine("UnAuthDir: {0}", UnAuthDir.Message) ' Catch paths that are too long. Catch LongPath As PathTooLongException Console.WriteLine("{0}", LongPath.Message) End Try End Sub End Classusing System; using System.IO; class Program { static void Main(string[] args) { // Create a DirectoryInfo object of the starting directory. DirectoryInfo diTop = new DirectoryInfo(@"d:\"); try { // Enumerate the files just in the top directory. foreach (var fi in diTop.EnumerateFiles()) { try { // Display each file over 10 MB; if (fi.Length > 10000000) { Console.WriteLine("{0}\t\t{1}", fi.FullName, fi.Length.ToString("N0")); } } // Catch unauthorized access to a file. catch (UnauthorizedAccessException UnAuthTop) { Console.WriteLine("{0}", UnAuthTop.Message); } } // Enumerate all subdirectories. foreach (var di in diTop.EnumerateDirectories("*")) { try { // Enumerate each file in each subdirectory. foreach (var fi in di.EnumerateFiles("*", SearchOption.AllDirectories)) { try { // Display each file over 10 MB; if (fi.Length > 10000000) { Console.WriteLine("{0}\t\t{1}", fi.FullName, fi.Length.ToString("N0")); } } // Catch unauthorized access to a file. catch (UnauthorizedAccessException UnAuthFile) { Console.WriteLine("UnAuthFile: {0}", UnAuthFile.Message); } } } // Catch unauthorized access to a subdirectory. catch (UnauthorizedAccessException UnAuthSubDir) { Console.WriteLine("UnAuthSubDir: {0}", UnAuthSubDir.Message); } } } // Catch error in directory path. catch (DirectoryNotFoundException DirNotFound) { Console.WriteLine("{0}", DirNotFound.Message); } // Catch unauthorized access to a first tier directory. catch (UnauthorizedAccessException UnAuthDir) { Console.WriteLine("UnAuthDir: {0}", UnAuthDir.Message); } // Catch paths that are too long. catch (PathTooLongException LongPath) { Console.WriteLine("{0}", LongPath.Message); } } }
在枚举的目录或文件中移除打开句柄
创建自定义方法（在 Visual Basic 中为函数）以包含枚举代码。
将 MethodImplAttribute 特性和 NoInlining 选项应用于新方法。 例如：
[MethodImplAttribute(MethodImplOptions.NoInlining)] Private void Enumerate()包括以下方法调用，以在枚举代码后运行：
GC.Collect() 方法（无参数）。