Directory.Exists(String) 方法 (System.IO)

2023-04-19 11:57| 来源: 网络整理| 查看: 265

Directory.Exists(String) 方法参考定义命名空间: System.IO 程序集:mscorlib.dll, System.IO.FileSystem.dll 程序集:System.IO.FileSystem.dll 程序集:System.Runtime.dll 程序集:mscorlib.dll 程序集:netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

确定给定路径是否引用磁盘上的现有目录。

public: static bool Exists(System::String ^ path); public static bool Exists (string path); public static bool Exists (string? path); static member Exists : string -> bool Public Shared Function Exists (path As String) As Boolean 参数 path String

要测试的路径。

返回 Boolean

如果 path 指向现有目录，则为 true；如果该目录不存在或者在尝试确定指定目录是否存在时出错，则为 false。

示例

以下示例在命令行上采用文件或目录名称数组，确定它是哪种名称，并相应地对其进行处理。

// For File::Exists, Directory::Exists using namespace System; using namespace System::IO; using namespace System::Collections; // Insert logic for processing found files here. void ProcessFile( String^ path ) { Console::WriteLine( "Processed file '{0}'.", path ); } // Process all files in the directory passed in, recurse on any directories // that are found, and process the files they contain. void ProcessDirectory( String^ targetDirectory ) { // Process the list of files found in the directory. array^fileEntries = Directory::GetFiles( targetDirectory ); IEnumerator^ files = fileEntries->GetEnumerator(); while ( files->MoveNext() ) { String^ fileName = safe_cast(files->Current); ProcessFile( fileName ); } // Recurse into subdirectories of this directory. array^subdirectoryEntries = Directory::GetDirectories( targetDirectory ); IEnumerator^ dirs = subdirectoryEntries->GetEnumerator(); while ( dirs->MoveNext() ) { String^ subdirectory = safe_cast(dirs->Current); ProcessDirectory( subdirectory ); } } int main( int argc, char *argv[] ) { for ( int i = 1; i < argc; i++ ) { String^ path = gcnew String(argv[ i ]); if ( File::Exists( path ) ) { // This path is a file ProcessFile( path ); } else if ( Directory::Exists( path ) ) { // This path is a directory ProcessDirectory( path ); } else { Console::WriteLine( "{0} is not a valid file or directory.", path ); } } } // For File.Exists, Directory.Exists using System; using System.IO; using System.Collections; public class RecursiveFileProcessor { public static void Main(string[] args) { foreach(string path in args) { if(File.Exists(path)) { // This path is a file ProcessFile(path); } else if(Directory.Exists(path)) { // This path is a directory ProcessDirectory(path); } else { Console.WriteLine("{0} is not a valid file or directory.", path); } } } // Process all files in the directory passed in, recurse on any directories // that are found, and process the files they contain. public static void ProcessDirectory(string targetDirectory) { // Process the list of files found in the directory. string [] fileEntries = Directory.GetFiles(targetDirectory); foreach(string fileName in fileEntries) ProcessFile(fileName); // Recurse into subdirectories of this directory. string [] subdirectoryEntries = Directory.GetDirectories(targetDirectory); foreach(string subdirectory in subdirectoryEntries) ProcessDirectory(subdirectory); } // Insert logic for processing found files here. public static void ProcessFile(string path) { Console.WriteLine("Processed file '{0}'.", path); } } module RecursiveFileProcessor open System.IO // Insert logic for processing found files here. let processFile path = printfn $"Processed file '%s{path}'." // Process all files in the directory passed in, recurse on any directories // that are found, and process the files they contain. let rec processDirectory targetDirectory = // Process the list of files found in the directory. let fileEntries = Directory.GetFiles targetDirectory for fileName in fileEntries do processFile fileName // Recurse into subdirectories of this directory. let subdirectoryEntries = Directory.GetDirectories targetDirectory for subdirectory in subdirectoryEntries do processDirectory subdirectory [] let main args = for path in args do if File.Exists path then // This path is a file processFile path elif Directory.Exists path then // This path is a directory processDirectory path else printfn $"{path} is not a valid file or directory." 0 ' For File.Exists, Directory.Exists Imports System.IO Imports System.Collections Public Class RecursiveFileProcessor Public Overloads Shared Sub Main(ByVal args() As String) Dim path As String For Each path In args If File.Exists(path) Then ' This path is a file. ProcessFile(path) Else If Directory.Exists(path) Then ' This path is a directory. ProcessDirectory(path) Else Console.WriteLine("{0} is not a valid file or directory.", path) End If End If Next path End Sub ' Process all files in the directory passed in, recurse on any directories ' that are found, and process the files they contain. Public Shared Sub ProcessDirectory(ByVal targetDirectory As String) Dim fileEntries As String() = Directory.GetFiles(targetDirectory) ' Process the list of files found in the directory. Dim fileName As String For Each fileName In fileEntries ProcessFile(fileName) Next fileName Dim subdirectoryEntries As String() = Directory.GetDirectories(targetDirectory) ' Recurse into subdirectories of this directory. Dim subdirectory As String For Each subdirectory In subdirectoryEntries ProcessDirectory(subdirectory) Next subdirectory End Sub ' Insert logic for processing found files here. Public Shared Sub ProcessFile(ByVal path As String) Console.WriteLine("Processed file '{0}'.", path) End Sub End Class 注解

允许 path 参数指定相对路径信息或绝对路径信息。相对路径信息被解释为相对于当前工作目录。

在检查目录是否存在之前， path 将从参数末尾删除尾随空格。

参数的 path 区分大小写对应于运行代码的文件系统的区分大小写。例如，它在 NTFS 上不区分大小写， (默认 Windows 文件系统) ，在 Linux 文件系统上区分大小写。

如果对目录没有最低只读权限，该方法 Exists 将返回 false。

如果在尝试确定指定文件是否存在时发生任何错误，该方法 Exists 将返回 false 。在引发异常的情况下，可能会发生这种情况，例如传递包含无效字符或字符过多的文件名、磁盘失败或缺失，或者调用方没有读取文件的权限。

适用于另请参阅 DirectoryInfo 文件和流 I/O 如何：从文件中读取文本如何：将文本写入文件

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