如何：枚举目录和文件

项目
05/10/2023

在处理目录和文件的大型集合时，可枚举的集合能够比数组提供更好的性能。要枚举目录和文件，请使用可返回目录和文件名的可枚举集合的方法或其 DirectoryInfo、FileInfo 或 FileSystemInfo 对象。

如果只想搜索并返回目录名称或文件名，请使用 Directory 类的枚举方法。若要搜索并返回目录或文件的其他属性，请使用 DirectoryInfo 和 FileSystemInfo 类。

可以使用这些方法中的可枚举集合作为集合类（如 List<T>）的构造函数的 IEnumerable<T> 参数。

下表总结了返回可枚举的文件和目录集合的方法：

搜索并返回	使用方法
目录名称	Directory.EnumerateDirectories
目录信息 (DirectoryInfo)	DirectoryInfo.EnumerateDirectories
文件名	Directory.EnumerateFiles
文件信息 (FileInfo)	DirectoryInfo.EnumerateFiles
文件系统条目名称	Directory.EnumerateFileSystemEntries
文件系统条目信息 (FileSystemInfo)	DirectoryInfo.EnumerateFileSystemInfos
目录和文件名称	Directory.EnumerateFileSystemEntries

注意

虽然可以使用可选的 SearchOption 枚举的 AllDirectories 选项迅速枚举父目录的子目录中的所有文件，但 UnauthorizedAccessException 错误可能会使枚举不完整。可以通过先枚举目录，然后枚举文件来捕获这些异常。

示例：使用目录类

以下示例使用 Directory.EnumerateDirectories(String) 方法获取指定路径中顶级目录名称的列表。

using System;
using System.Collections.Generic;
using System.IO;

class Program
{
    private static void Main(string[] args)
    {
        try
        {
            // Set a variable to the My Documents path.
            string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

            List<string> dirs = new List<string>(Directory.EnumerateDirectories(docPath));

            foreach (var dir in dirs)
            {
                Console.WriteLine($"{dir.Substring(dir.LastIndexOf(Path.DirectorySeparatorChar) + 1)}");
            }
            Console.WriteLine($"{dirs.Count} directories found.");
        }
        catch (UnauthorizedAccessException ex)
        {
            Console.WriteLine(ex.Message);
        }
        catch (PathTooLongException ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

Imports System.Collections.Generic
Imports System.IO

Module Module1

    Sub Main()
        Try
            Dim dirPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)

            Dim dirs As List(Of String) = New List(Of String)(Directory.EnumerateDirectories(dirPath))

            For Each folder In dirs
                Console.WriteLine($"{dir.Substring(dir.LastIndexOf(Path.DirectorySeparatorChar) + 1)}")
            Next
            Console.WriteLine($"{dirs.Count} directories found.")
        Catch ex As UnauthorizedAccessException
            Console.WriteLine(ex.Message)
        Catch ex As PathTooLongException
            Console.WriteLine(ex.Message)
        End Try

    End Sub
End Module

以下示例使用 Directory.EnumerateFiles(String, String, SearchOption) 方法递归枚举目录中的所有文件名以及与特定模式匹配的子目录。然后它读取每个文件的每一行，并显示包含指定字符串的行及其文件名和路径。

using System;
using System.IO;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        try
        {
            // Set a variable to the My Documents path.
            string docPath =
            Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

            var files = from file in Directory.EnumerateFiles(docPath, "*.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($"{f.File}\t{f.Line}");
            }
            Console.WriteLine($"{files.Count().ToString()} files found.");
        }
        catch (UnauthorizedAccessException uAEx)
        {
            Console.WriteLine(uAEx.Message);
        }
        catch (PathTooLongException pathEx)
        {
            Console.WriteLine(pathEx.Message);
        }
    }
}

Imports System.IO
Imports System.Xml.Linq

Module Module1

    Sub Main()
        Try
            Dim docPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
            Dim files = From chkFile In Directory.EnumerateFiles(docPath, "*.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($"{f.File}\t{f.Line}")
            Next
            Console.WriteLine($"{files.Count} files found.")
        Catch uAEx As UnauthorizedAccessException
            Console.WriteLine(uAEx.Message)
        Catch pathEx As PathTooLongException
            Console.WriteLine(pathEx.Message)
        End Try
    End Sub
End Module

示例：使用 DirectoryInfo 类

下面的示例使用 DirectoryInfo.EnumerateDirectories 方法列出顶级目录的集合，这些顶级目录的 CreationTimeUtc 早于某个 DateTime 值。

using System;
using System.IO;

namespace EnumDir
{
    class Program
    {
        static void Main(string[] args)
        {
            // Set a variable to the Documents path.
            string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

            DirectoryInfo dirPrograms = new DirectoryInfo(docPath);
            DateTime StartOf2009 = new DateTime(2009, 01, 01);

            var dirs = from dir in dirPrograms.EnumerateDirectories()
            where dir.CreationTimeUtc > StartOf2009
            select new
            {
                ProgDir = dir,
            };

            foreach (var di in dirs)
            {
                Console.WriteLine($"{di.ProgDir.Name}");
            }
        }
    }
}
// </Snippet1>

Imports System.IO

Module Module1

    Sub Main()

        Dim dirPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
        Dim dirPrograms As New DirectoryInfo(dirPath)
        Dim StartOf2009 As New DateTime(2009, 1, 1)

        Dim dirs = From dir In dirPrograms.EnumerateDirectories()
                   Where dir.CreationTimeUtc > StartOf2009

        For Each di As DirectoryInfo In dirs
            Console.WriteLine("{0}", di.Name)
        Next

    End Sub

End Module

下例使用 DirectoryInfo.EnumerateFiles 方法列出 Length 超过 10MB 的所有文件。此示例先枚举顶级目录以捕获可能的未授权访问异常，再枚举文件。

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        // Set a variable to the My Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        DirectoryInfo diTop = new DirectoryInfo(docPath);

        try
        {
            foreach (var fi in diTop.EnumerateFiles())
            {
                try
                {
                    // Display each file over 10 MB;
                    if (fi.Length > 10000000)
                    {
                        Console.WriteLine($"{fi.FullName}\t\t{fi.Length.ToString("N0")}");
                    }
                }
                catch (UnauthorizedAccessException unAuthTop)
                {
                    Console.WriteLine($"{unAuthTop.Message}");
                }
            }

            foreach (var di in diTop.EnumerateDirectories("*"))
            {
                try
                {
                    foreach (var fi in di.EnumerateFiles("*", SearchOption.AllDirectories))
                    {
                        try
                        {
                            // Display each file over 10 MB;
                            if (fi.Length > 10000000)
                            {
                                Console.WriteLine($"{fi.FullName}\t\t{fi.Length.ToString("N0")}");
                            }
                        }
                        catch (UnauthorizedAccessException unAuthFile)
                        {
                            Console.WriteLine($"unAuthFile: {unAuthFile.Message}");
                        }
                    }
                }
                catch (UnauthorizedAccessException unAuthSubDir)
                {
                    Console.WriteLine($"unAuthSubDir: {unAuthSubDir.Message}");
                }
            }
        }
        catch (DirectoryNotFoundException dirNotFound)
        {
            Console.WriteLine($"{dirNotFound.Message}");
        }
        catch (UnauthorizedAccessException unAuthDir)
        {
            Console.WriteLine($"unAuthDir: {unAuthDir.Message}");
        }
        catch (PathTooLongException longPath)
        {
            Console.WriteLine($"{longPath.Message}");
        }
    }
}

Imports System.IO

Class Program
    Public Shared Sub Main(ByVal args As String())
        Dim dirPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
        Dim diTop As New DirectoryInfo(dirPath)
        Try
            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 unAuthTop As UnauthorizedAccessException
                    Console.WriteLine($"{unAuthTop.Message}")
                End Try
            Next

            For Each di In diTop.EnumerateDirectories("*")
                Try
                    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 unAuthFile As UnauthorizedAccessException
                            Console.WriteLine($"unAuthFile: {unAuthFile.Message}")
                        End Try
                    Next
                Catch unAuthSubDir As UnauthorizedAccessException
                    Console.WriteLine($"unAuthSubDir: {unAuthSubDir.Message}")
                End Try
            Next
        Catch dirNotFound As DirectoryNotFoundException
            Console.WriteLine($"{dirNotFound.Message}")
        Catch unAuthDir As UnauthorizedAccessException
            Console.WriteLine($"unAuthDir: {unAuthDir.Message}")
        Catch longPath As PathTooLongException
            Console.WriteLine($"{longPath.Message}")
        End Try
    End Sub
End Class

请参阅

文件和流 I/O

通过

如何：枚举目录和文件

示例：使用目录类

示例：使用 DirectoryInfo 类

请参阅

其他资源