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这个类功能很强。可以实时监测文件系统的变化。
https://msdn.microsoft.com/zh-cn/library/system.io.filesystemwatcher.aspx
事件
使用不如预期。重复发送消息、结束时并不会发送消息。
例如，拷贝一个文件，在文件拷贝完成后进行操作，但我们无法知道什么时候拷贝操作完成。
拷贝文件时，响应的事件:Created、Changed、Changed(...)
其实，知道这些就已经可以了。
新增文件时，首先收到Created消息。下面我们需要做一些额外的工作来监视文件是否写入完毕。
这里使用了独占方式读取文件，发生异常，表示写入未完成。
using (FileStream fs = new System.IO.FileStream(item.FullPath, FileMode.Open, FileAccess.Read, FileShare.None)) { fs.Close(); }
当收到Created消息后，在while中独占读取文件。
创建监听对象，扩展了多类型监听。
FileWatcher.Start(FullPath, "*.txt|*.dwg");
public class FileWatcher { string _folder; string _filter; System.IO.FileSystemWatcher _watcher; private FileWatcher(string folder):this(folder,string.Empty) { } private FileWatcher(string folder,string filter) { if (string.IsNullOrEmpty(folder)) throw new ArgumentNullException("folder"); this._folder = folder; this._filter = filter; _watcher = new System.IO.FileSystemWatcher(this._folder); _watcher.NotifyFilter = NotifyFilters.CreationTime | NotifyFilters.LastWrite |NotifyFilters.FileName; _watcher.IncludeSubdirectories = true; if (!string.IsNullOrEmpty(this._filter)) _watcher.Filter = this._filter; _watcher.Changed += new FileSystemEventHandler(OnChanged); _watcher.Created += new FileSystemEventHandler(OnChanged); _watcher.Deleted += new FileSystemEventHandler(OnChanged); // _watcher.Renamed += new RenamedEventHandler(OnRenamed); _watcher.EnableRaisingEvents = true; } public static void Start(string folder, string filter) { foreach (var arg in filter.Split(‘|‘)) new FileWatcher(folder, arg); } private void OnChanged(object source, FileSystemEventArgs e) { WatcherList.GetInstance().Add(new WatcherInfo() { FullPath = e.FullPath, ChangeType = e.ChangeType }); } private void OnRenamed(object source, RenamedEventArgs e) { } }
监听对象实体
internal class WatcherInfo { /// <summary> /// 文件全路径 /// </summary> public string FullPath { get; set; } /// <summary> /// 事件发生事件 /// </summary> internal DateTime EventTime { get; set; } /// <summary> /// 类型.1,Created.2,Deleted。3.Changed /// </summary> public WatcherChangeTypes ChangeType { get; set; } /// <summary> /// 0:正常 /// </summary> internal int Status { get; set; } }
/// <summary> /// 假设同名的文件只进行一次操作 /// </summary> internal class WatcherList { private static readonly object syncObject = new object(); private static WatcherList singleton; private Queue<WatcherInfo> All = new Queue<WatcherInfo>(); ManualResetEvent allDone = new ManualResetEvent(false); private WatcherList() { System.Threading.ThreadPool.QueueUserWorkItem(new WaitCallback(this.Work)); } public static WatcherList GetInstance() { if (singleton == null) { lock (syncObject) { if(singleton==null) singleton = new WatcherList(); } } return singleton; } public void Add(WatcherInfo i) { if (i == null|| string.IsNullOrEmpty(i.FullPath)) return; if (i.ChangeType == WatcherChangeTypes.Created) Enqueue(i); else if (i.ChangeType == WatcherChangeTypes.Deleted) Dequeue(i); } private void Enqueue(WatcherInfo i) { if (i.ChangeType != WatcherChangeTypes.Created) return; bool isadd = false; lock (syncObject) { foreach (var item in All) { if (i.FullPath == item.FullPath && i.ChangeType == WatcherChangeTypes.Created) { isadd = true; break; } } if (!isadd) { i.Status = 0; i.EventTime = DateTime.Now; All.Enqueue(i); allDone.Set(); } } } private void Dequeue(WatcherInfo i) { if (i.ChangeType != WatcherChangeTypes.Deleted) return; lock (syncObject) { foreach (var item in All) { if (i.FullPath == item.FullPath) item.Status = 1; } } } private void Work(Object o) { while (true) { if (All.Count == 0) allDone.WaitOne(); if (All.Count == 0)/*必要*/ continue; var item = All.Peek(); if (item.Status == 1) All.Dequeue(); else { if (!System.IO.File.Exists(item.FullPath)) { { All.Dequeue(); continue; } } try { using (FileStream fs = new System.IO.FileStream(item.FullPath, FileMode.Open, FileAccess.Read, FileShare.None)) { fs.Close(); } /*
System.IO.File.Copy
*/ All.Dequeue(); } catch (Exception e) { System.Threading.Thread.Sleep(1000); } } } } }
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原文地址：http://www.cnblogs.com/lucika/p/5166551.html
