C#中的文件系统监视器

Question

目前，我有一个Windows服务，它不断地监控4个文件夹。我使用过FileSystemWatchers来监控文件夹。

但每次添加新文件夹时，我都必须卸载该服务，添加一个新的filesystemwatcher，然后安装该服务。

我正在考虑使它成为动态的或数据库驱动的，这样我就不必在每次程序需要监控新文件夹时卸载并重新安装该服务。

我如何才能做到这一点？

提前谢谢。

Answer 1

这里有一个使用XML和Linq2XML的演示，并检查配置文件的更改：

class Program
{
    static List<FileSystemWatcher> _watchers = new List<FileSystemWatcher>();
    static bool _shouldReload = false;

    static void WaitReady(string fileName)
    {
        while (true)
        {
            try
            {
                using (Stream stream = System.IO.File.Open(fileName, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
                {
                    if (stream != null)
                    {
                        System.Diagnostics.Trace.WriteLine(string.Format("Output file {0} ready.", fileName));
                        break;
                    }
                }
            }
            catch (FileNotFoundException ex)
            {
                System.Diagnostics.Trace.WriteLine(string.Format("Output file {0} not yet ready ({1})", fileName, ex.Message));
            }
            catch (IOException ex)
            {
                System.Diagnostics.Trace.WriteLine(string.Format("Output file {0} not yet ready ({1})", fileName, ex.Message));
            }
            catch (UnauthorizedAccessException ex)
            {
                System.Diagnostics.Trace.WriteLine(string.Format("Output file {0} not yet ready ({1})", fileName, ex.Message));
            }
            Thread.Sleep(500);
        }
    }

    static void Main(string[] args)
    {
        var configWatcher = new FileSystemWatcher(Path.GetDirectoryName(Path.GetFullPath("config.xml")), "config.xml");
        configWatcher.Changed += (o, e) =>
        {
            lock (_watchers)
            {
                _watchers.ForEach(w => { w.EnableRaisingEvents = false; w.Dispose(); });
                _watchers.Clear();
            }

            _shouldReload = true;
        };

        configWatcher.EnableRaisingEvents = true;

        Thread t = new Thread((ThreadStart)(() => {
            while (true)
            {
                Thread.Sleep(5000); // reload only every five seconds (safety measure)
                if (_shouldReload)
                {
                    _shouldReload = false;
                    Console.WriteLine("Reloading configuration.");
                    WaitReady(Path.GetFullPath("config.xml"));
                    loadConfigAndRun();
                }
            }
        }));

        t.IsBackground = true;
        t.Start();

        loadConfigAndRun();

        Console.ReadLine();
    }

    static void loadConfigAndRun()
    {
        var config = XElement.Load("config.xml").Elements();
        var paths = from watcher in config select watcher.Attribute("Folder").Value;

        foreach (var path in paths)
        {
            var watcher = new FileSystemWatcher(path);
            watcher.Created += new FileSystemEventHandler(watcher_Changed);
            watcher.Changed += new FileSystemEventHandler(watcher_Changed);
            watcher.Deleted += new FileSystemEventHandler(watcher_Changed);
            watcher.Renamed += new RenamedEventHandler(watcher_Renamed);
            watcher.EnableRaisingEvents = true;
            _watchers.Add(watcher);
        }
    }

    static void toggleWatcher(string path)
    {
        var watcher = _watchers.FirstOrDefault(w => w.Path == path);

        if (watcher != null)
        {
            watcher.EnableRaisingEvents = !watcher.EnableRaisingEvents;
        }
    }

    static void watcher_Renamed(object sender, RenamedEventArgs e)
    {
        var watcher = sender as FileSystemWatcher;

        Console.WriteLine("Something renamed in " + watcher.Path);
    }

    static void watcher_Changed(object sender, FileSystemEventArgs e)
    {
        var watcher = sender as FileSystemWatcher;

        Console.WriteLine("Something changed in " + watcher.Path);
    }
}

这是config.xml：

<?xml version="1.0" encoding="utf-8" ?>
<Watchers>
  <Watcher Folder="d:\ktm"></Watcher>
  <Watcher Folder="c:\windows"></Watcher>
</Watchers>

Answer 2

您可以使用XML配置文件，应用程序定期读取该文件并缓存新文件夹。这些将放在app.settings文件中。

<configuration>
    <appSettings>
        <add key = "FolderToWatch" value = "C:\SomeFolder\" />
        <add key = "FolderToWatch" value = "C:\SomeFolder\AnotherOne\" />
        <add key = "FolderToWatch" value = "D:\LastOne\" />
    </appSettings>
</configuration>

Answer 3

使用配置文件添加新位置。然后，只要将新位置添加到配置文件中，就需要重新启动该服务。