FileSystemWatcher.Changed Event
Assembly: System (in system.dll)
'Declaration Public Event Changed As FileSystemEventHandler 'Usage Dim instance As FileSystemWatcher Dim handler As FileSystemEventHandler AddHandler instance.Changed, handler
/** @event */ public void add_Changed (FileSystemEventHandler value) /** @event */ public void remove_Changed (FileSystemEventHandler value)
In JScript, you can handle the events defined by a class, but you cannot define your own.
Not applicable.
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.
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| Common file system operations might raise more than one event. For example, when a file is moved from one directory to another, several OnChanged and some OnCreated and OnDeleted events might be raised. Moving a file is a complex operation that consists of multiple simple operations, therefore raising multiple events. Likewise, some applications (for example, antivirus software) might cause additional file system events that are detected by FileSystemWatcher. |
Use NotifyFilter to restrict the number of notifications raised when this event is handled.
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| The Changed event is raised unexpectedly when a file is renamed, but is not raised when a directory is renamed. To watch for renaming, use the Renamed event. |
The following example uses the Changed event to display the file path to the console whenever the watched file is changed.
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
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
Note: