FileSystemWatcher.Changed Zdarzenie

Definicja

Występuje, gdy zostanie zmieniony plik lub katalog w określonym Path.Occurs when a file or directory in the specified Path is changed.

public:
 event System::IO::FileSystemEventHandler ^ Changed;
[System.IO.IODescription("Occurs when a file/directory change matches the filter")]
[System.IO.IODescription("FSW_Changed")]
public event System.IO.FileSystemEventHandler Changed;
member this.Changed : System.IO.FileSystemEventHandler 
Public Custom Event Changed As FileSystemEventHandler 
Atrybuty

Przykłady

Poniższy przykład używa zdarzenia Changed, aby wyświetlić ścieżkę pliku do konsoli za każdym razem, gdy plik obserwowany zostanie zmieniony.The following example uses the Changed event to display the file path to the console whenever the watched file is changed.

#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();
}
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

Uwagi

Zdarzenie Changed jest zgłaszane w przypadku zmiany rozmiaru, atrybutów systemowych, czasu ostatniego zapisu, czasu ostatniego dostępu lub uprawnień zabezpieczeń pliku lub katalogu w monitorowanym katalogu.The Changed event is raised when changes are made to the size, system attributes, last write time, last access time, or security permissions of a file or directory in the directory being monitored.

Uwaga

Typowe operacje systemu plików mogą spowodować wystąpienie więcej niż jednego zdarzenia.Common file system operations might raise more than one event. Na przykład gdy plik jest przenoszony z jednego katalogu do innego, mogą zostać zgłoszone kilka OnChanged i zdarzeń OnCreated i OnDeleted.For example, when a file is moved from one directory to another, several OnChanged and some OnCreated and OnDeleted events might be raised. Przeniesienie pliku jest skomplikowaną operacją, która składa się z wielu prostych operacji, a tym samym wywołuje wiele zdarzeń.Moving a file is a complex operation that consists of multiple simple operations, therefore raising multiple events. Podobnie niektóre aplikacje (na przykład oprogramowanie antywirusowe) mogą spowodować dodatkowe zdarzenia systemu plików, które są wykrywane przez FileSystemWatcher.Likewise, some applications (for example, antivirus software) might cause additional file system events that are detected by FileSystemWatcher.

Użyj NotifyFilter, aby ograniczyć liczbę powiadomień wywoływanych w przypadku obsługi tego zdarzenia.Use NotifyFilter to restrict the number of notifications raised when this event is handled.

Uwaga

Zdarzenie Changed jest nieoczekiwanie zgłaszane w przypadku zmiany nazwy pliku, ale nie jest zgłaszane, gdy zostanie zmieniona nazwa katalogu.The Changed event is raised unexpectedly when a file is renamed, but is not raised when a directory is renamed. Aby obejrzeć zmianę nazwy, użyj zdarzenia Renamed.To watch for renaming, use the Renamed event.

Uwaga

Kolejność, w której zdarzenie Changed jest zgłaszane w odniesieniu do innych zdarzeń FileSystemWatcher może ulec zmianie, gdy właściwość SynchronizingObject nie jest null.The order in which the Changed event is raised in relation to the other FileSystemWatcher events may change when the SynchronizingObject property is not null.

Dotyczy

Zobacz też