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。