FileSystemEventHandler 委托
定义
重要
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表示将处理 FileSystemWatcher 类的 Changed、Created 或 Deleted 事件的方法。
public delegate void FileSystemEventHandler(System::Object ^ sender, FileSystemEventArgs ^ e);public delegate void FileSystemEventHandler(object sender, FileSystemEventArgs e);type FileSystemEventHandler = delegate of obj * FileSystemEventArgs -> unitPublic Delegate Sub FileSystemEventHandler(sender As Object, e As FileSystemEventArgs)参数
- sender
- Object
事件源。
包含事件数据的 FileSystemEventArgs。
示例
以下示例演示如何创建 FileSystemWatcher 来监视文件更改， (创建、删除、重命名、更改) 磁盘驱动器上发生的更改。 该示例还演示如何正确接收错误通知。
using System;
using System.IO;
class Program
{
static void Main(string[] args)
{
// Create a FileSystemWatcher to monitor all files on drive C.
FileSystemWatcher fsw = new FileSystemWatcher("C:\\");
// Watch for changes in LastAccess and LastWrite times, and
// the renaming of files or directories.
fsw.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName |NotifyFilters.DirectoryName;
// Register a handler that gets called when a
// file is created, changed, or deleted.
fsw.Changed += new FileSystemEventHandler(OnChanged);
fsw.Created += new FileSystemEventHandler(OnChanged);
fsw.Deleted += new FileSystemEventHandler(OnChanged);
// Register a handler that gets called when a file is renamed.
fsw.Renamed += new RenamedEventHandler(OnRenamed);
// Register a handler that gets called if the
// FileSystemWatcher needs to report an error.
fsw.Error += new ErrorEventHandler(OnError);
// Begin watching.
fsw.EnableRaisingEvents = true;
Console.WriteLine("Press \'Enter\' to quit the sample.");
Console.ReadLine();
}
// This method is called when a file is created, changed, or deleted.
private static void OnChanged(object source, FileSystemEventArgs e)
{
// Show that a file has been created, changed, or deleted.
WatcherChangeTypes wct = e.ChangeType;
Console.WriteLine("File {0} {1}", e.FullPath, wct.ToString());
}
// This method is called when a file is renamed.
private static void OnRenamed(object source, RenamedEventArgs e)
{
// Show that a file has been renamed.
WatcherChangeTypes wct = e.ChangeType;
Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, wct.ToString());
}
// This method is called when the FileSystemWatcher detects an error.
private static void OnError(object source, ErrorEventArgs e)
{
// Show that an error has been detected.
Console.WriteLine("The FileSystemWatcher has detected an error");
// Give more information if the error is due to an internal buffer overflow.
if (e.GetException().GetType() == typeof(InternalBufferOverflowException))
{
// This can happen if Windows is reporting many file system events quickly
// and internal buffer of the FileSystemWatcher is not large enough to handle this
// rate of events. The InternalBufferOverflowException error informs the application
// that some of the file system events are being lost.
Console.WriteLine(("The file system watcher experienced an internal buffer overflow: " + e.GetException().Message));
}
}
}
Imports System.IO
Module Module1
Sub Main()
' Create a FileSystemWatcher to monitor all files on drive C.
Dim fsw As New FileSystemWatcher("C:\")
' Watch for changes in LastAccess and LastWrite times, and
' the renaming of files or directories.
fsw.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite _
Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)
' Register a handler that gets called when a
' file is created, changed, or deleted.
AddHandler fsw.Changed, New FileSystemEventHandler(AddressOf OnChanged)
' The commented line of code below is a shorthand of the above line.
' AddHandler fsw.Changed, AddressOf OnChanged
' NOTE: The shorthand version is used in the remainder of this code.
' FileSystemEventHandler
AddHandler fsw.Created, AddressOf OnChanged
' FileSystemEventHandler
AddHandler fsw.Deleted, AddressOf OnChanged
' Register a handler that gets called when a file is renamed.
' RenamedEventHandler
AddHandler fsw.Renamed, AddressOf OnRenamed
' Register a handler that gets called if the
' FileSystemWatcher needs to report an error.
' ErrorEventHandler
AddHandler fsw.Error, AddressOf OnError
' Begin watching.
fsw.EnableRaisingEvents = True
' Wait for the user to quit the program.
Console.WriteLine("Press 'Enter' to quit the sample.")
Console.ReadLine()
End Sub
' This method is called when a file is created, changed, or deleted.
Private Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs)
' Show that a file has been created, changed, or deleted.
Dim wct As WatcherChangeTypes = e.ChangeType
Console.WriteLine("File {0} {1}", e.FullPath, wct.ToString())
End Sub
' This method is called when a file is renamed.
Private Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs)
' Show that a file has been renamed.
Dim wct As WatcherChangeTypes = e.ChangeType
Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, wct.ToString())
End Sub
' This method is called when the FileSystemWatcher detects an error.
Private Sub OnError(ByVal source As Object, ByVal e As ErrorEventArgs)
' Show that an error has been detected.
Console.WriteLine("The FileSystemWatcher has detected an error")
' Give more information if the error is due to an internal buffer overflow.
If TypeOf e.GetException Is InternalBufferOverflowException Then
' This can happen if Windows is reporting many file system events quickly
' and internal buffer of the FileSystemWatcher is not large enough to handle this
' rate of events. The InternalBufferOverflowException error informs the application
' that some of the file system events are being lost.
Console.WriteLine( _
"The file system watcher experienced an internal buffer overflow: " _
+ e.GetException.Message)
End If
End Sub
End Module
注解
创建 FileSystemEventHandler 委托时，需要标识将处理该事件的方法。 若要将事件与事件处理程序关联，请将该委托的一个实例添加到事件中。 除非移除了该委托，否则每当发生该事件时就会调用事件处理程序。 有关事件处理程序委托的详细信息，请参阅 处理和引发事件。
扩展方法
| GetMethodInfo(Delegate) |
获取指示指定委托表示的方法的对象。 |
