c#使用filesystemwatcher实时监控文件目录的添加和删除

/// <summary>
    /// 文件监控类，用于监控指定目录下文件以及文件夹的变化
    /// </summary>
    public class FileWatcher
    {
        private FileSystemWatcher _watcher=null;
        private string _path=string.Empty;
        private string _filter=string.Empty;
        private bool _isWatch=false;
        private CustomQueue<FileChangeInformation> _queue=null;

        /// <summary>
        /// 监控是否正在运行
        /// </summary>
        public bool IsWatch
        {
            get
            {
                return _isWatch;
            }
        }

        /// <summary>
        /// 文件变更信息队列
        /// </summary>
        public CustomQueue<FileChangeInformation> FileChangeQueue
        {
            get
            {
                return _queue;
            }
        }

        /// <summary>
        /// 初始化FileWatcher类
        /// </summary>
        /// <param name="path">监控路径</param>
        public FileWatcher(string path)
        {
            _path=path;
            _queue=new CustomQueue<FileChangeInformation>();
        }
        /// <summary>
        /// 初始化FileWatcher类，并指定是否持久化文件变更消息
        /// </summary>
        /// <param name="path">监控路径</param>
        /// <param name="isPersistence">是否持久化变更消息</param>
        /// <param name="persistenceFilePath">持久化保存路径</param>
        public FileWatcher(string path, bool isPersistence, string persistenceFilePath)
        {
            _path=path;
            _queue=new CustomQueue<FileChangeInformation>(isPersistence, persistenceFilePath);
        }

        /// <summary>
        /// 初始化FileWatcher类，并指定是否监控指定类型文件
        /// </summary>
        /// <param name="path">监控路径</param>
        /// <param name="filter">指定类型文件，格式如:*.txt,*.doc,*.rar</param>
        public FileWatcher(string path, string filter)
        {
            _path=path;
            _filter=filter;
            _queue=new CustomQueue<FileChangeInformation>();
        }

        /// <summary>
        /// 初始化FileWatcher类，并指定是否监控指定类型文件，是否持久化文件变更消息
        /// </summary>
        /// <param name="path">监控路径</param>
        /// <param name="filter">指定类型文件，格式如:*.txt,*.doc,*.rar</param>
        /// <param name="isPersistence">是否持久化变更消息</param>
        /// <param name="persistenceFilePath">持久化保存路径</param>
        public FileWatcher(string path, string filter, bool isPersistence, string persistenceFilePath)
        {
            _path=path;
            _filter=filter;
            _queue=new CustomQueue<FileChangeInformation>(isPersistence, persistenceFilePath);
        }

        /// <summary>
        /// 打开文件监听器
        /// </summary>
        public void Open()
        {
            if (!Directory.Exists(_path))
            {
                Directory.CreateDirectory(_path);
            }

            if (string.IsNullOrEmpty(_filter))
            {
                _watcher=new FileSystemWatcher(_path);
            }
            else
            {
                _watcher=new FileSystemWatcher(_path, _filter);
            }
            //注册监听事件
            _watcher.Created +=new FileSystemEventHandler(OnProcess);
            _watcher.Changed +=new FileSystemEventHandler(OnProcess);
            _watcher.Deleted +=new FileSystemEventHandler(OnProcess);
            _watcher.Renamed +=new RenamedEventHandler(OnFileRenamed);
            _watcher.IncludeSubdirectories=true;
            _watcher.EnableRaisingEvents=true;
            _isWatch=true;
        }

        /// <summary>
        /// 关闭监听器
        /// </summary>
        public void Close()
        {
            _isWatch=false;
            _watcher.Created -=new FileSystemEventHandler(OnProcess);
            _watcher.Changed -=new FileSystemEventHandler(OnProcess);
            _watcher.Deleted -=new FileSystemEventHandler(OnProcess);
            _watcher.Renamed -=new RenamedEventHandler(OnFileRenamed);
            _watcher.EnableRaisingEvents=false;
            _watcher=null;
        }

        /// <summary>
        /// 获取一条文件变更消息
        /// </summary>
        /// <returns></returns>
        public FileChangeInformation Get()
        {
            FileChangeInformation info=null;
            if (_queue.Count > 0)
            {
                lock (_queue)
                {
                    info=_queue.Dequeue();
                }
            }
            return info;
        }

        /// <summary>
        /// 监听事件触发的方法
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void OnProcess(object sender, FileSystemEventArgs e)
        {
            try
            {
                FileChangeType changeType=FileChangeType.Unknow;
                if (e.ChangeType==WatcherChangeTypes.Created)
                {
                    if (File.GetAttributes(e.FullPath)==FileAttributes.Directory)
                    {
                        changeType=FileChangeType.NewFolder;
                    }
                    else
                    {
                        changeType=FileChangeType.NewFile;
                    }
                }
                else if (e.ChangeType==WatcherChangeTypes.Changed)
                {
                    //部分文件创建时同样触发文件变化事件，此时记录变化操作没有意义
                    //如果
                    if (_queue.SelectAll(
                        delegate(FileChangeInformation fcm)
                        {
                            return fcm.NewPath==e.FullPath && fcm.ChangeType==FileChangeType.Change;
                        }).Count<FileChangeInformation>() > 0)
                    {
                        return;
                    }

                    //文件夹的变化，只针对创建，重命名和删除动作，修改不做任何操作。
                    //因为文件夹下任何变化同样会触发文件的修改操作，没有任何意义.
                    if (File.GetAttributes(e.FullPath)==FileAttributes.Directory)
                    {
                        return;
                    }

                    changeType=FileChangeType.Change;
                }
                else if (e.ChangeType==WatcherChangeTypes.Deleted)
                {
                    changeType=FileChangeType.Delete;
                }

                //创建消息，并压入队列中
                FileChangeInformation info=new FileChangeInformation(Guid.NewGuid().ToString(), changeType, e.FullPath, e.FullPath, e.Name, e.Name);
                _queue.Enqueue(info);
            }
            catch
            {
                Close();
            }
        }

        /// <summary>
        /// 文件或目录重命名时触发的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void OnFileRenamed(object sender, RenamedEventArgs e)
        {
            try
            {
                //创建消息，并压入队列中
                FileChangeInformation info=new FileChangeInformation(Guid.NewGuid().ToString(), FileChangeType.Rename, e.OldFullPath, e.FullPath, e.OldName, e.Name);
                _queue.Enqueue(info);
            }
            catch
            {
                Close();
            }
        }
    }