FileSystemWatcher 类

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命名空间:

System.IO

程序集:

System.IO.FileSystem.Watcher.dll, System.dll, netstandard.dll

侦听文件系统更改通知，并在目录或目录中的文件发生更改时引发事件。Listens to the file system change notifications and raises events when a directory, or file in a directory, changes.

本文内容

1. 定义
2. 示例
3. 注解
4. 构造函数
5. 属性
6. 方法
7. 事件
8. 适用于
9. 另请参阅

public ref class FileSystemWatcher : IDisposable

public ref class FileSystemWatcher : System::ComponentModel::Component, System::ComponentModel::ISupportInitialize

public ref class FileSystemWatcher : System::ComponentModel::Component, IDisposable, System::ComponentModel::ISupportInitialize

C#复制

public class FileSystemWatcher : IDisposable

C#复制

public class FileSystemWatcher : System.ComponentModel.Component, System.ComponentModel.ISupportInitialize

C#复制

[System.IO.IODescription("FileSystemWatcherDesc")]
public class FileSystemWatcher : System.ComponentModel.Component, System.ComponentModel.ISupportInitialize

C#复制

public class FileSystemWatcher : System.ComponentModel.Component, IDisposable, System.ComponentModel.ISupportInitialize

C#复制

[System.IO.IODescription("")]
public class FileSystemWatcher : System.ComponentModel.Component, System.ComponentModel.ISupportInitialize

type FileSystemWatcher = class
    interface IDisposable

type FileSystemWatcher = class
    inherit Component
    interface ISupportInitialize

type FileSystemWatcher = class
    inherit Component
    interface IDisposable
    interface ISupportInitialize

Public Class FileSystemWatcher
Implements IDisposable

Public Class FileSystemWatcher
Inherits Component
Implements ISupportInitialize

Public Class FileSystemWatcher
Inherits Component
Implements IDisposable, ISupportInitialize

继承

Object

FileSystemWatcher

继承

Object

MarshalByRefObject

Component

FileSystemWatcher

属性

IODescriptionAttributeIODescriptionAttribute

实现

ISupportInitialize

示例

下面的示例创建一个 FileSystemWatcher 以监视运行时指定的目录。The following example creates a FileSystemWatcher to watch the directory specified at run time. 组件设置为监视 LastWrite 和 LastAccess 时间的更改、创建、删除或重命名目录中的文本文件。The component is set to watch for changes in LastWrite and LastAccess time, the creation, deletion, or renaming of text files in the directory. 如果更改、创建或删除了某个文件，则该文件的路径将打印到控制台。If a file is changed, created, or deleted, the path to the file prints to the console. 重命名文件后，旧路径和新路径将打印到控制台。When a file is renamed, the old and new paths print to the console.

#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Security::Permissions;

public ref class Watcher
{
private:
   // Define the event handlers.
   static void OnChanged( Object^ /*source*/, FileSystemEventArgs^ e )
   {
      // Specify what is done when a file is changed, created, or deleted.
      Console::WriteLine( "File: {0} {1}", e->FullPath, e->ChangeType );
   }

   static void OnRenamed( Object^ /*source*/, RenamedEventArgs^ e )
   {
      // Specify what is done when a file is renamed.
      Console::WriteLine( "File: {0} renamed to {1}", e->OldFullPath, e->FullPath );
   }

public:
   [PermissionSet(SecurityAction::Demand, Name="FullTrust")]
   int static run()
   {
      array<String^>^args = System::Environment::GetCommandLineArgs();

      // If a directory is not specified, exit program.
      if ( args->Length != 2 )
      {
         // Display the proper way to call the program.
         Console::WriteLine( "Usage: Watcher.exe (directory)" );
         return 0;
      }

      // Create a new FileSystemWatcher and set its properties.
      FileSystemWatcher^ watcher = gcnew FileSystemWatcher;
      watcher->Path = args[ 1 ];

      /* Watch for changes in LastAccess and LastWrite times, and 
          the renaming of files or directories. */
      watcher->NotifyFilter = static_cast<NotifyFilters>(NotifyFilters::LastAccess |
            NotifyFilters::LastWrite | NotifyFilters::FileName | NotifyFilters::DirectoryName);

      // Only watch text files.
      watcher->Filter = "*.txt";

      // Add event handlers.
      watcher->Changed += gcnew FileSystemEventHandler( Watcher::OnChanged );
      watcher->Created += gcnew FileSystemEventHandler( Watcher::OnChanged );
      watcher->Deleted += gcnew FileSystemEventHandler( Watcher::OnChanged );
      watcher->Renamed += gcnew RenamedEventHandler( Watcher::OnRenamed );

      // Begin watching.
      watcher->EnableRaisingEvents = true;

      // Wait for the user to quit the program.
      Console::WriteLine( "Press \'q\' to quit the sample." );
      while ( Console::Read() != 'q' );

      return 0;
   }
};

int main() {
   Watcher::run();
}

C#复制

using System;
using System.IO;
using System.Security.Permissions;

public class Watcher
{
    public static void Main()
    {
        Run();
    }

    [PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
    private static void Run()
    {
        string[] args = Environment.GetCommandLineArgs();

        // If a directory is not specified, exit program.
        if (args.Length != 2)
        {
            // Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)");
            return;
        }

        // Create a new FileSystemWatcher and set its properties.
        using (FileSystemWatcher watcher = new FileSystemWatcher())
        {
            watcher.Path = args[1];

            // Watch for changes in LastAccess and LastWrite times, and
            // the renaming of files or directories.
            watcher.NotifyFilter = NotifyFilters.LastAccess
                                 | NotifyFilters.LastWrite
                                 | NotifyFilters.FileName
                                 | NotifyFilters.DirectoryName;

            // Only watch text files.
            watcher.Filter = "*.txt";

            // Add event handlers.
            watcher.Changed += OnChanged;
            watcher.Created += OnChanged;
            watcher.Deleted += OnChanged;
            watcher.Renamed += OnRenamed;

            // Begin watching.
            watcher.EnableRaisingEvents = true;

            // Wait for the user to quit the program.
            Console.WriteLine("Press 'q' to quit the sample.");
            while (Console.Read() != 'q') ;
        }
    }

    // Define the event handlers.
    private static void OnChanged(object source, FileSystemEventArgs e) =>
        // Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine($"File: {e.FullPath} {e.ChangeType}");

    private static void OnRenamed(object source, RenamedEventArgs e) =>
        // Specify what is done when a file is renamed.
        Console.WriteLine($"File: {e.OldFullPath} renamed to {e.FullPath}");
}

Imports System.IO
Imports System.Security.Permissions

Public Class Watcher

    Public Shared Sub Main()

        Run()

    End Sub

    <PermissionSet(SecurityAction.Demand, Name:="FullTrust")>
    Private Shared Sub Run()

        Dim args() As String = Environment.GetCommandLineArgs()

        ' If a directory is not specified, exit the program.
        If args.Length <> 2 Then
            ' Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)")
            Return
        End If

        ' Create a new FileSystemWatcher and set its properties.
        Using watcher As New FileSystemWatcher()
            watcher.Path = args(1)

            ' Watch for changes in LastAccess and LastWrite times, and
            ' the renaming of files or directories. 
            watcher.NotifyFilter = (NotifyFilters.LastAccess _
                                 Or NotifyFilters.LastWrite _
                                 Or NotifyFilters.FileName _
                                 Or NotifyFilters.DirectoryName)

            ' Only watch text files.
            watcher.Filter = "*.txt"

            ' Add event handlers.
            AddHandler watcher.Changed, AddressOf OnChanged
            AddHandler watcher.Created, AddressOf OnChanged
            AddHandler watcher.Deleted, AddressOf OnChanged
            AddHandler watcher.Renamed, AddressOf OnRenamed

            ' Begin watching.
            watcher.EnableRaisingEvents = True

            ' Wait for the user to quit the program.
            Console.WriteLine("Press 'q' to quit the sample.")
            While Chr(Console.Read()) <> "q"c
            End While
        End Using
    End Sub

    ' Define the event handlers.
    Private Shared Sub OnChanged(source As Object, e As FileSystemEventArgs)
        ' Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine($"File: {e.FullPath} {e.ChangeType}")
    End Sub

    Private Shared Sub OnRenamed(source As Object, e As RenamedEventArgs)
        ' Specify what is done when a file is renamed.
        Console.WriteLine($"File: {e.OldFullPath} renamed to {e.FullPath}")
    End Sub

End Class

注解

使用 FileSystemWatcher 来监视指定目录中的更改。Use FileSystemWatcher to watch for changes in a specified directory. 可以监视指定目录的文件和子目录中的更改。You can watch for changes in files and subdirectories of the specified directory. 你可以创建一个组件来监视本地计算机、网络驱动器或远程计算机上的文件。You can create a component to watch files on a local computer, a network drive, or a remote computer.

若要监视所有文件中的更改，请将 Filter 属性设置为空字符串（””）或使用通配符（”*。*”）。To watch for changes in all files, set the Filter property to an empty string (“”) or use wildcards (“*.*”). 若要查看特定文件，请将 Filter 属性设置为文件名。To watch a specific file, set the Filter property to the file name. 例如，若要监视文件 MyDoc 中的更改，请将 Filter 属性设置为 “MyDoc”。For example, to watch for changes in the file MyDoc.txt, set the Filter property to “MyDoc.txt”. 还可以监视特定类型的文件中的更改。You can also watch for changes in a certain type of file. 例如，若要监视文本文件中的更改，请将 Filter 属性设置为 “*.txt”。For example, to watch for changes in text files, set the Filter property to “*.txt”.

可以在目录或文件中监视几种类型的更改。There are several types of changes you can watch for in a directory or file. 例如，你可以监视 Attributes、LastWrite 日期和时间，或者文件或目录的 Size 的更改。For example, you can watch for changes in Attributes, the LastWrite date and time, or the Size of files or directories. 这是通过将 NotifyFilter 属性设置为 NotifyFilters 值之一来完成的。This is done by setting the NotifyFilter property to one of the NotifyFilters values. 有关可以观看的更改类型的详细信息，请参阅 NotifyFilters。For more information on the type of changes you can watch, see NotifyFilters.

可以监视文件或目录的重命名、删除或创建。You can watch for renaming, deletion, or creation of files or directories. 例如，若要监视是否重命名了文本文件，请将 Filter 属性设置为 “* .txt”，并使用为其参数指定的 Renamed 调用 WaitForChanged 方法。For example, to watch for renaming of text files, set the Filter property to “*.txt” and call the WaitForChanged method with a Renamed specified for its parameter.

Windows 操作系统会将文件更改的组件通知到 FileSystemWatcher所创建的缓冲区中。The Windows operating system notifies your component of file changes in a buffer created by the FileSystemWatcher. 如果短时间内有很多更改，则缓冲区可能溢出。If there are many changes in a short time, the buffer can overflow. 这会使组件失去对目录中的更改的跟踪，并且它将只提供覆盖通知。This causes the component to lose track of changes in the directory, and it will only provide blanket notification. 用 InternalBufferSize 属性增加缓冲区的大小会消耗大量资源，因为它来自无法换出到磁盘的非分页内存，因此，请将缓冲区保持得足够小但足以避免丢失任何文件更改事件。Increasing the size of the buffer with the InternalBufferSize property is expensive, as it comes from non-paged memory that cannot be swapped out to disk, so keep the buffer as small yet large enough to not miss any file change events. 若要避免缓冲区溢出，请使用 NotifyFilter 和 IncludeSubdirectories 属性，以便可以筛选出不需要的更改通知。To avoid a buffer overflow, use the NotifyFilter and IncludeSubdirectories properties so you can filter out unwanted change notifications.

有关 FileSystemWatcher实例的初始属性值的列表，请参阅 FileSystemWatcher 构造函数。For a list of initial property values for an instance of FileSystemWatcher, see the FileSystemWatcher constructor.

使用 FileSystemWatcher 类时，请注意以下各项。Please note the following when using the FileSystemWatcher class.

• 不会忽略隐藏的文件。Hidden files are not ignored.

• 在某些系统中，FileSystemWatcher 使用短8.3 文件名格式对文件进行更改。In some systems, FileSystemWatcher reports changes to files using the short 8.3 file name format. 例如，将 “LongFileName” 更改为 “LongFil ~。Lon “。For example, a change to “LongFileName.LongExtension” could be reported as “LongFil~.Lon”.

• 此类包含应用于所有成员的类级别的链接要求和继承要求。This class contains a link demand and an inheritance demand at the class level that applies to all members. 当直接调用方或派生类不具有完全信任权限时，将引发 SecurityException。A SecurityException is thrown when either the immediate caller or the derived class does not have full-trust permission. 有关安全要求的详细信息，请参阅链接需求。For details about security demands, see Link Demands.

• 可以为用于通过网络监视目录的 InternalBufferSize 属性设置的最大大小为 64 KB。The maximum size you can set for the InternalBufferSize property for monitoring a directory over the network is 64 KB.

备注

不支持在 Windows 98 上运行 FileSystemWatcher。Running FileSystemWatcher on Windows 98 is not supported.

复制和移动文件夹Copying and moving folders

操作系统和 FileSystemWatcher 对象会将剪切和粘贴操作或移动操作解释为文件夹及其内容的重命名操作。The operating system and FileSystemWatcher object interpret a cut-and-paste action or a move action as a rename action for a folder and its contents. 如果将包含文件的文件夹剪切并粘贴到被监视的文件夹中，则 FileSystemWatcher 对象只会将该文件夹报告为新文件夹，但不报告其内容，因为它们实质上只是已重命名。If you cut and paste a folder with files into a folder being watched, the FileSystemWatcher object reports only the folder as new, but not its contents because they are essentially only renamed.

若要通知文件夹内容已移动或复制到监视的文件夹，请提供下表中所建议 OnChanged 和 OnRenamed 事件处理程序方法。To be notified that the contents of folders have been moved or copied into a watched folder, provide OnChanged and OnRenamed event handler methods as suggested in the following table.

事件和缓冲区大小Events and Buffer Sizes

请注意，有几个因素可能会影响引发的文件系统更改事件，如下所述：Note that several factors can affect which file system change events are raised, as described by the following:

• 常见的文件系统操作可能会引发多个事件。Common file system operations might raise more than one event. 例如，当文件从一个目录移到另一个目录时，可能会引发多个 OnChanged，某些 OnCreated 和 OnDeleted 事件。For example, when a file is moved from one directory to another, several OnChanged and some OnCreated and OnDeleted events might be raised. 移动文件是一项复杂的操作，它包含多个简单操作，因此引发了多个事件。Moving a file is a complex operation that consists of multiple simple operations, therefore raising multiple events. 同样，某些应用程序（例如，防病毒软件）可能会导致 FileSystemWatcher检测到的其他文件系统事件。Likewise, some applications (for example, antivirus software) might cause additional file system events that are detected by FileSystemWatcher.

• FileSystemWatcher 可以监视磁盘，只要它们未被切换或删除。The FileSystemWatcher can watch disks as long as they are not switched or removed. FileSystemWatcher 不会引发 Cd 和 Dvd 事件，因为时间戳和属性无法更改。The FileSystemWatcher does not raise events for CDs and DVDs, because time stamps and properties cannot change. 远程计算机必须安装其中一个所需的平台，组件才能正常运行。Remote computers must have one of the required platforms installed for the component to function properly.

请注意，当超过缓冲区大小时，FileSystemWatcher 可能会遗漏事件。Note that a FileSystemWatcher may miss an event when the buffer size is exceeded. 若要避免丢失事件，请遵循以下准则：To avoid missing events, follow these guidelines:

• 通过设置 InternalBufferSize 属性增加缓冲区大小。Increase the buffer size by setting the InternalBufferSize property.

• 避免监视包含长文件名的文件，因为较长的文件名有助于填充缓冲区。Avoid watching files with long file names, because a long file name contributes to filling up the buffer. 请考虑使用较短的名称重命名这些文件。Consider renaming these files using shorter names.

• 使事件处理代码尽可能简短。Keep your event handling code as short as possible.

构造函数

属性

方法

事件

适用于

.NET Core

3.13.02.22.12.01.11.0

.NET Framework

4.84.7.24.7.14.74.6.24.6.14.64.5.24.5.14.54.03.53.02.01.1

.NET Standard

2.12.0

Xamarin.Android

7.1

Xamarin.iOS

10.8

Xamarin.Mac

3.0

另请参阅

• NotifyFilter
• NotifyFilters
• FileSystemEventArgs
• FileSystemEventHandler
• Filter
• IncludeSubdirectories
• InternalBufferOverflowException
• RenamedEventArgs
• RenamedEventHandler
• WaitForChangedResult
• WatcherChangeTypes
• 在 Windows 窗体中使用 FileSystemWatcher 组件