FileSystemWatcher.Changed Zdarzenie

Definicja

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

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

Typ zdarzenia

FileSystemEventHandler
Atrybuty

Przykłady

Poniższy przykład używa Changed zdarzenia do wyświetlania ścieżki 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.

#include "pch.h"

using namespace System;
using namespace System::IO;

class MyClassCPP
{
public:

    int static Run()
    {
        FileSystemWatcher^ watcher = gcnew FileSystemWatcher("C:\\path\\to\\folder");

        watcher->NotifyFilter = static_cast<NotifyFilters>(NotifyFilters::Attributes
                                                         | NotifyFilters::CreationTime
                                                         | NotifyFilters::DirectoryName
                                                         | NotifyFilters::FileName
                                                         | NotifyFilters::LastAccess
                                                         | NotifyFilters::LastWrite
                                                         | NotifyFilters::Security
                                                         | NotifyFilters::Size);

        watcher->Changed += gcnew FileSystemEventHandler(MyClassCPP::OnChanged);
        watcher->Created += gcnew FileSystemEventHandler(MyClassCPP::OnCreated);
        watcher->Deleted += gcnew FileSystemEventHandler(MyClassCPP::OnDeleted);
        watcher->Renamed += gcnew RenamedEventHandler(MyClassCPP::OnRenamed);
        watcher->Error   += gcnew ErrorEventHandler(MyClassCPP::OnError);

        watcher->Filter = "*.txt";
        watcher->IncludeSubdirectories = true;
        watcher->EnableRaisingEvents = true;

        Console::WriteLine("Press enter to exit.");
        Console::ReadLine();

        return 0;
    }

private:

    static void OnChanged(Object^ sender, FileSystemEventArgs^ e)
    {
        if (e->ChangeType != WatcherChangeTypes::Changed)
        {
            return;
        }
        Console::WriteLine("Changed: {0}", e->FullPath);
    }

    static void OnCreated(Object^ sender, FileSystemEventArgs^ e)
    {
        Console::WriteLine("Created: {0}", e->FullPath);
    }

    static void OnDeleted(Object^ sender, FileSystemEventArgs^ e)
    {
        Console::WriteLine("Deleted: {0}", e->FullPath);
    }

    static void OnRenamed(Object^ sender, RenamedEventArgs^ e)
    {
        Console::WriteLine("Renamed:");
        Console::WriteLine("    Old: {0}", e->OldFullPath);
        Console::WriteLine("    New: {0}", e->FullPath);
    }

    static void OnError(Object^ sender, ErrorEventArgs^ e)
    {
        PrintException(e->GetException());
    }

    static void PrintException(Exception^ ex)
    {
        if (ex != nullptr)
        {
            Console::WriteLine("Message: {0}", ex->Message);
            Console::WriteLine("Stacktrace:");
            Console::WriteLine(ex->StackTrace);
            Console::WriteLine();
            PrintException(ex->InnerException);
        }
    }
};


int main()
{
    MyClassCPP::Run();
}
using System;
using System.IO;

namespace MyNamespace
{
    class MyClassCS
    {
        static void Main()
        {
            using var watcher = new FileSystemWatcher(@"C:\path\to\folder");

            watcher.NotifyFilter = NotifyFilters.Attributes
                                 | NotifyFilters.CreationTime
                                 | NotifyFilters.DirectoryName
                                 | NotifyFilters.FileName
                                 | NotifyFilters.LastAccess
                                 | NotifyFilters.LastWrite
                                 | NotifyFilters.Security
                                 | NotifyFilters.Size;

            watcher.Changed += OnChanged;
            watcher.Created += OnCreated;
            watcher.Deleted += OnDeleted;
            watcher.Renamed += OnRenamed;
            watcher.Error += OnError;

            watcher.Filter = "*.txt";
            watcher.IncludeSubdirectories = true;
            watcher.EnableRaisingEvents = true;

            Console.WriteLine("Press enter to exit.");
            Console.ReadLine();
        }

        private static void OnChanged(object sender, FileSystemEventArgs e)
        {
            if (e.ChangeType != WatcherChangeTypes.Changed)
            {
                return;
            }
            Console.WriteLine($"Changed: {e.FullPath}");
        }

        private static void OnCreated(object sender, FileSystemEventArgs e)
        {
            string value = $"Created: {e.FullPath}";
            Console.WriteLine(value);
        }

        private static void OnDeleted(object sender, FileSystemEventArgs e) =>
            Console.WriteLine($"Deleted: {e.FullPath}");

        private static void OnRenamed(object sender, RenamedEventArgs e)
        {
            Console.WriteLine($"Renamed:");
            Console.WriteLine($"    Old: {e.OldFullPath}");
            Console.WriteLine($"    New: {e.FullPath}");
        }

        private static void OnError(object sender, ErrorEventArgs e) =>
            PrintException(e.GetException());

        private static void PrintException(Exception? ex)
        {
            if (ex != null)
            {
                Console.WriteLine($"Message: {ex.Message}");
                Console.WriteLine("Stacktrace:");
                Console.WriteLine(ex.StackTrace);
                Console.WriteLine();
                PrintException(ex.InnerException);
            }
        }
    }
}
Imports System.IO

Namespace MyNamespace

    Class MyClassVB

        Shared Sub Main()
            Using watcher = New FileSystemWatcher("C:\path\to\folder")
                watcher.NotifyFilter = NotifyFilters.Attributes Or
                                       NotifyFilters.CreationTime Or
                                       NotifyFilters.DirectoryName Or
                                       NotifyFilters.FileName Or
                                       NotifyFilters.LastAccess Or
                                       NotifyFilters.LastWrite Or
                                       NotifyFilters.Security Or
                                       NotifyFilters.Size

                AddHandler watcher.Changed, AddressOf OnChanged
                AddHandler watcher.Created, AddressOf OnCreated
                AddHandler watcher.Deleted, AddressOf OnDeleted
                AddHandler watcher.Renamed, AddressOf OnRenamed
                AddHandler watcher.Error, AddressOf OnError

                watcher.Filter = "*.txt"
                watcher.IncludeSubdirectories = True
                watcher.EnableRaisingEvents = True

                Console.WriteLine("Press enter to exit.")
                Console.ReadLine()
            End Using
        End Sub

        Private Shared Sub OnChanged(sender As Object, e As FileSystemEventArgs)
            If e.ChangeType <> WatcherChangeTypes.Changed Then
                Return
            End If
            Console.WriteLine($"Changed: {e.FullPath}")
        End Sub

        Private Shared Sub OnCreated(sender As Object, e As FileSystemEventArgs)
            Dim value As String = $"Created: {e.FullPath}"
            Console.WriteLine(value)
        End Sub

        Private Shared Sub OnDeleted(sender As Object, e As FileSystemEventArgs)
            Console.WriteLine($"Deleted: {e.FullPath}")
        End Sub

        Private Shared Sub OnRenamed(sender As Object, e As RenamedEventArgs)
            Console.WriteLine($"Renamed:")
            Console.WriteLine($"    Old: {e.OldFullPath}")
            Console.WriteLine($"    New: {e.FullPath}")
        End Sub

        Private Shared Sub OnError(sender As Object, e As ErrorEventArgs)
            PrintException(e.GetException())
        End Sub

        Private Shared Sub PrintException(ex As Exception)
            If ex IsNot Nothing Then
                Console.WriteLine($"Message: {ex.Message}")
                Console.WriteLine("Stacktrace:")
                Console.WriteLine(ex.StackTrace)
                Console.WriteLine()
                PrintException(ex.InnerException)
            End If
        End Sub

    End Class

End Namespace

Uwagi

ChangedZdarzenie 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, OnChanged OnCreated OnDeleted mogą zostać zgłoszone kilka i zdarzenia.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 program 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 wyzwalanych w przypadku obsługi tego zdarzenia.Use NotifyFilter to restrict the number of notifications raised when this event is handled.

Uwaga

ChangedZdarzenie jest nieoczekiwane zgłoszone w przypadku zmiany nazwy pliku, ale nie jest zgłaszane w przypadku zmiany nazwy 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 Renamed zdarzenia.To watch for renaming, use the Renamed event.

Uwaga

Kolejność, w której Changed zdarzenie jest zgłaszane w odniesieniu do innych FileSystemWatcher zdarzeń, może ulec zmianie, gdy SynchronizingObject Właściwość 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