FileSystemWatcher.Changed FileSystemWatcher.Changed FileSystemWatcher.Changed FileSystemWatcher.Changed Event

Definizione

Viene generato alla modifica di un file o di una directory nella proprietà Path specificata.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 
Attributi

Esempi

Nell'esempio seguente viene usato Changed l'evento per visualizzare il percorso del file alla console ogni volta che il file controllato viene modificato.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
Imports System.IO
Imports System.Security.Permissions
Imports Microsoft.VisualBasic

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

Commenti

L' Changed evento viene generato quando vengono apportate modifiche alle dimensioni, agli attributi di sistema, all'ora dell'ultima scrittura, all'ora dell'ultimo accesso o alle autorizzazioni di sicurezza di un file o di una directory nella directory monitorata.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.

Nota

Le operazioni comuni di file system possono generare più di un evento.Common file system operations might raise more than one event. Ad esempio, quando un file viene spostato da una directory a un'altra, OnChanged OnCreated è possibile che OnDeleted vengano generati alcuni eventi e.For example, when a file is moved from one directory to another, several OnChanged and some OnCreated and OnDeleted events might be raised. Lo stato di un file è un'operazione complessa costituita da più semplici operazioni, che pertanto generano più eventi.Moving a file is a complex operation that consists of multiple simple operations, therefore raising multiple events. Analogamente, alcune applicazioni (ad esempio, il software antivirus) potrebbero causare eventi di file system aggiuntivi rilevati da FileSystemWatcher.Likewise, some applications (for example, antivirus software) might cause additional file system events that are detected by FileSystemWatcher.

Utilizzare NotifyFilter questa opzione per limitare il numero di notifiche generate quando viene gestito l'evento.Use NotifyFilter to restrict the number of notifications raised when this event is handled.

Nota

L' Changed evento viene generato in modo imprevisto quando un file viene rinominato, ma non viene generato quando una directory viene rinominata.The Changed event is raised unexpectedly when a file is renamed, but is not raised when a directory is renamed. Per controllare la ridenominazione, usare l' Renamed evento.To watch for renaming, use the Renamed event.

Nota

L'ordine in cui l' Changed evento viene generato in relazione agli altri FileSystemWatcher eventi può variare quando la SynchronizingObject proprietà non nullè.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.

Si applica a

Vedi anche