使用延迟的FileSystemWatcher来避免重复触发事件-飞外

问题：

程序里需要监视某个目录下的文件变化情况: 一旦目录中出现新文件或者旧的文件被覆盖，程序需要读取文件内容并进行处理；但在实际处理中发现当一个文件产生变化时，Change事件被反复触发了好几次。这样可能的结果是造成同一文件的重复处理。
解决方法：

针对上面的问题，于是写了一个可以延迟FileSystemWatcher发出的事件的Class DelayFileSystemWatcher。

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;

namespace Utility
{
 public class DelayFileSystemWatcher
 {
 private readonly Timer m_Timer;
 private readonly Int32 m_TimerInterval;
 private readonly FileSystemWatcher m_FileSystemWatcher;
 private readonly FileSystemEventHandler m_FileSystemEventHandler;
 private readonly Dictionary String, FileSystemEventArgs m_ChangedFiles = new Dictionary string, FileSystemEventArgs 

 public DelayFileSystemWatcher(string path, string filter, FileSystemEventHandler watchHandler, int timerInterval)
 {
 m_Timer = new Timer(OnTimer, null, Timeout.Infinite, Timeout.Infinite);
 m_FileSystemWatcher = new FileSystemWatcher(path, filter);
 m_FileSystemWatcher.NotifyFilter = NotifyFilters.FileName | NotifyFilters.LastWrite | NotifyFilters.CreationTime;
 m_FileSystemWatcher.Created += fileSystemWatcher_Changed;
 m_FileSystemWatcher.Changed += fileSystemWatcher_Changed;
 m_FileSystemWatcher.Deleted += fileSystemWatcher_Changed;
 m_FileSystemWatcher.Renamed += fileSystemWatcher_Changed;
 m_FileSystemWatcher.EnableRaisingEvents = true;
 m_FileSystemEventHandler = watchHandler;
 m_TimerInterval = timerInterval;
 }

 public void fileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
 {
 lock (m_ChangedFiles)
 {
 if (!m_ChangedFiles.ContainsKey(e.Name))
 {
 m_ChangedFiles.Add(e.Name, e);
 }
 }
 m_Timer.Change(m_TimerInterval, Timeout.Infinite);
 }

 private void OnTimer(object state)
 {
 Dictionary String, FileSystemEventArgs tempChangedFiles = new Dictionary String, FileSystemEventArgs 

 lock (m_ChangedFiles)
 {
 foreach (KeyValuePair string, FileSystemEventArgs changedFile in m_ChangedFiles)
 {
 tempChangedFiles.Add(changedFile.Key, changedFile.Value);
 }
 m_ChangedFiles.Clear();
 }

 foreach (KeyValuePair string, FileSystemEventArgs changedFile in tempChangedFiles)
 {
 m_FileSystemEventHandler(this, changedFile.Value);
 }
 }
 }
}

使用方式如下：

 s_DelayFileSystemWatcher = new DelayFileSystemWatcher(@"C:\Temp", "*.xml", fileSystemWatcher_Changed, 1500);

 private static void fileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
 {
 switch (e.ChangeType)
 {
 case WatcherChangeTypes.Created:
 //TODO
 break;
 case WatcherChangeTypes.Deleted:
 //TODO 
 break;
 case WatcherChangeTypes.Changed:
 //TODO
 break;
 default:
 break;
 }
 }