C#采用FileSystemWatcher实现监视磁盘文件变更的方法

本文实例讲述了C#采用FileSystemWatcher实现监视磁盘文件变更的方法。分享给大家供大家参考。具体实现方法如下：

简化需求：有一个简化了的需求是这样的：有一个拍照程序在运行，一旦抓拍之后则将图片文件存储至某目录，然后图片要上传至远程服务器并update数据库。

原需求：原先的需求是这样的：有一台PDA扫码枪，一个IP照相机放置在下线区传送带上方。当PDA扫描箱子上的条码，触发相机拍照，将图片流传至远端服务器，找到对应的条码，将图片存储并更新数据库。

然而我不知道PDA扫描的瞬间如何与IP相机通信（蓝牙或WLAN？），其实关键是我不知道怎样使用IP相机的外触发功能，增加蓝牙触发器？也不知道怎样hack或ssh到这个相机（应该是linux的吧），所以只能先使用简化需求的版本。

而简化需求的版本，关键就是监视文件夹内容变化与上传文件流。

昨天问了下度娘，C#中的监视组件名字叫做FileSystemWatcher。

于是写了个demo，可以监视所有逻辑盘或者某个文件夹。

使用方法：

1.直接打开是监视所有逻辑磁盘文件变化。

2.或者传递参数，监视某一路径文件变化。如图，监视e盘

源代码如下：

namespace FileSystemWatcherDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            //watcher组

            FileSystemWatcher[] watchers;

            //若未传递参数,则监视所有文件系统,包括CD-ROM（不可用）,可移动磁盘（不可用）等

            if (args.Length == 0)

            {

                string[] drivers = Directory.GetLogicalDrives();

                watchers = new FileSystemWatcher[drivers.Length];
                for (int i = 0; i < drivers.Length; i++)

                {

                    try

                    {

                        watchers[i] = new FileSystemWatcher { Path = drivers[i] };

                    }

                    catch (Exception ex)

                    {

                        Trace.TraceWarning(ex.Message);

                    }

                }

            }

            else

            {

                watchers = new FileSystemWatcher[1];

                watchers[0] = new FileSystemWatcher { Path = args[0] };

            }
            foreach (FileSystemWatcher w in watchers)

            {

                if (w == null) continue;
                w.Filter = "*";

                w.IncludeSubdirectories = true;

                w.EnableRaisingEvents = true;
                w.Created += onFileSystem_Changed;

                w.Deleted += onFileSystem_Changed;

                w.Changed += onFileSystem_Changed;

                w.Renamed += watcher_Renamed;

            }
            Console.ReadLine();

        }
        #region [ 检测文件是否占用 ]

        /// <summary>

        /// 检测文件是否占用

        /// </summary>

        /// <param name="filename"></param>

        /// <returns></returns>

        static bool IsFileReady(string filename)

        {

            var fi = new FileInfo(filename);

            FileStream fs = null;

            try

            {

                fs = fi.Open(FileMode.Open, FileAccess.Read, FileShare.None);

                return true;

            }

            catch (IOException)

            {

                return false;

            }
            finally

            {

                if (fs != null)

                    fs.Close();

            }

        }

        #endregion
        private static volatile object _lock = true;

        static void onFileSystem_Changed(object sender, FileSystemEventArgs e)

        {

            lock (_lock)

            {

                Console.ForegroundColor = ConsoleColor.DarkGray;

                Console.Write("[");

                Console.Write(DateTime.Now.ToString("HH:mm:ss"));

                Console.Write("] ");
                switch (e.ChangeType.ToString().ToLower())

                {

                    case "created":

                        //while (!IsFileReady(e.FullPath))

                        //{

                        //    if (!File.Exists(e.FullPath))

                        //        return;

                        //    Thread.Sleep(100);

                        //}

                        Console.ForegroundColor = ConsoleColor.Green;

                        Console.Write(e.ChangeType);

                        Console.ForegroundColor = ConsoleColor.White;

                        Console.Write(" ");

                        Console.Write(e.Name);

                        Console.Write(" ");

                        Console.ForegroundColor = ConsoleColor.DarkGray;

                        Console.Write(e.FullPath);
                        break;

                    case "deleted":

                        Console.ForegroundColor = ConsoleColor.Red;

                        Console.Write(e.ChangeType);

                        Console.ForegroundColor = ConsoleColor.White;

                        Console.Write(" ");

                        Console.Write(e.Name);

                        Console.Write(" ");

                        Console.ForegroundColor = ConsoleColor.DarkGray;

                        Console.Write(e.FullPath);

                        break;

                    case "changed":

                        Console.ForegroundColor = ConsoleColor.Cyan;

                        Console.Write(e.ChangeType);

                        Console.ForegroundColor = ConsoleColor.White;

                        Console.Write(" ");

                        Console.Write(e.Name);

                        Console.Write(" ");

                        Console.ForegroundColor = ConsoleColor.DarkGray;

                        Console.Write(e.FullPath);

                        break;

                }
                Console.Write("\r\n");

            }

        }

        static void watcher_Renamed(object sender, RenamedEventArgs e)

        {

            Console.ForegroundColor = ConsoleColor.Magenta;

            Console.Write(e.ChangeType);

            Console.ForegroundColor = ConsoleColor.White;

            Console.Write(" ");

            Console.Write(e.OldName);

            Console.Write(e.OldFullPath);

            Console.ForegroundColor = ConsoleColor.Yellow;

            Console.Write(" ");

            Console.Write(e.Name);

            Console.Write(e.FullPath);

            Console.Write(Thread.CurrentThread.Name);

            Console.Write("\r\n");

        }

    }

}

希望本文所述对大家的C#程序设计有所帮助。