一个目录下有文件产生是会产生什么系统事件，如何截获？

可以用FileSystemWatcher来监视目录下面文件的变化，FileSystemWatcher.Created 事件就是当在指定 Path 中创建文件和目录时发生。下面是MSDN中的一个例子：
public class Watcher
{    public static void Main()
    {        string[] args = System.Environment.GetCommandLineArgs();
 
        // If a directory is not specified, exit program.
        if(args.Length != 2)
        {
            // Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)");
            return;
        }        // Create a new FileSystemWatcher and set its properties.
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = args[1];
        /* Watch for changes in LastAccess and LastWrite times, and 
           the renaming of files or directories. */
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite 
           | NotifyFilters.FileName | NotifyFilters.DirectoryName;
        // Only watch text files.
        watcher.Filter = "*.txt";        // Add event handlers.
        watcher.Changed += new FileSystemEventHandler(OnChanged);
        watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Deleted += new FileSystemEventHandler(OnChanged);
        watcher.Renamed += new RenamedEventHandler(OnRenamed);        // Begin watching.
        watcher.EnableRaisingEvents = true;        // Wait for the user to quit the program.
        Console.WriteLine("Press \'q\' to quit the sample.");
        while(Console.Read()!='q');
    }    // Define the event handlers.
    private static void OnChanged(object source, FileSystemEventArgs e)
    {
        // Specify what is done when a file is changed, created, or deleted.
       Console.WriteLine("File: " +  e.FullPath + " " + e.ChangeType);
    }    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        // Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
    }
}