FileSystemWatcher.Changed イベント

.NET Framework クラス ライブラリ リファレンス

FileSystemWatcher.Changed イベント

指定した Path のファイルまたはディレクトリが変更されたときに発生します。

名前空間: System.IO
アセンブリ: System (system.dll 内)
構文

Visual Basic (宣言)

Public Event Changed As
 FileSystemEventHandler

Visual Basic (使用法)

Dim instance As FileSystemWatcher
Dim handler As FileSystemEventHandler

AddHandler instance.Changed, handler

C#

public event FileSystemEventHandler Changed

C++

public:
event FileSystemEventHandler^ Changed {
    void add (FileSystemEventHandler^ value);
    void remove (FileSystemEventHandler^ value);
}

J#

/** @event */
public void add_Changed (FileSystemEventHandler
 value)

/** @event */
public void remove_Changed (FileSystemEventHandler
 value)

JScript

JScript では、イベントは使用できますが、新規に宣言することはできません。

解説

Changed イベントは、監視しているディレクトリ内のファイルまたはディレクトリのサイズ、システム属性、最後の書き込み時刻、最後のアクセス時刻、またはセキュリティ アクセス許可が変更された場合に発生します。

メモ
一般的なファイル システム操作で、複数のイベントが発生することがあります。たとえば、あるディレクトリから別のディレクトリにファイルを移動するとき、複数の OnChanged、OnCreated、OnDeleted の各イベントが発生することがあります。ファイルの移動は、複数の単純な操作から構成される複雑な操作です。そのため、複数のイベントが発生します。同様に、一部のアプリケーション (ウイルス対策ソフトウェアなど) では追加のファイル システム イベントが発生し、FileSystemWatcher で検出されることがあります。

NotifyFilter を使用して、このイベントを処理するときに発生する通知の数を制限します。

メモ
ファイル名が変更されると Changed イベントが思いがけず発生しますが、ディレクトリ名が変更されたときには発生しません。名前の変更をウォッチするには、Renamed イベントを使用します。

使用例

Visual Basic

Public Class Watcher
    
    Public Shared Sub Main()
    
         Run()
  
    End Sub

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

      Dim args() As String
 = System.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.
        Dim 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 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: {0} renamed to {1}",
 e.OldFullPath, e.FullPath)
    End Sub
    
End Class

C#

public class Watcher
{

    public static void Main()
    {
    Run();

    }

    [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
    public static void Run()
    {
        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;
        }

        // Create a new FileSystemWatcher and set its properties.
        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 += new FileSystemEventHandler(OnChanged);
        watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Deleted += new FileSystemEventHandler(OnChanged);
        watcher.Renamed += new RenamedEventHandler(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: {0} renamed to {1}", e.OldFullPath, e.FullPath);
    }
}

C++

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' )
         ;
   }
};

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

J#

public class Watcher
{
    public static void main(String[]
 args1)
    {
    Run();
    } 

    /** @attribute PermissionSet(SecurityAction.Demand, Name="FullTrust")
     */
    public static void Run()
    {
        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;
        }

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

        /* Watch for changes in LastAccess
 and LastWrite times, and 
           the renaming of files or directories.
         */
        watcher.set_NotifyFilter
            (NotifyFilters.LastAccess |NotifyFilters.LastWrite |
            NotifyFilters.FileName | NotifyFilters.DirectoryName);

        // Only watch text files.
        watcher.set_Filter("*.txt");

        // Add event handlers.
        watcher.add_Changed(new FileSystemEventHandler(OnChanged));
        watcher.add_Created(new FileSystemEventHandler(OnChanged));
        watcher.add_Deleted(new FileSystemEventHandler(OnChanged));
        watcher.add_Renamed(new RenamedEventHandler(OnRenamed));

        // Begin watching.
        watcher.set_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.get_FullPath() + " "
 
            + e.get_ChangeType()));
    } //OnChanged

    private static void
 OnRenamed(Object source, RenamedEventArgs e)
    {
        // Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}",
            e.get_OldFullPath(),e.get_FullPath());
    } //OnRenamed
} //Watcher

プラットフォーム

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0

参照

関連項目
FileSystemWatcher クラス
FileSystemWatcher メンバ
System.IO 名前空間
FileSystemWatcher.NotifyFilter プロパティ
OnChanged
FileSystemEventArgs クラス
FileSystemEventHandler デリゲート