目录文件根据各条件排序

class FileSort : IComparer    {        private FileOrder _fileorder;        private FileAsc _fileasc;        /// <summary>        /// 构造函数        /// </summary>        public FileSort()            : this(FileOrder.Name, FileAsc.Asc)        { }        /// <summary>        /// 构造函数        /// </summary>        /// <param name="fileorder"></param>        public FileSort(FileOrder fileorder)            : this(fileorder, FileAsc.Asc)        { }        /// <summary>        /// 构造函数        /// </summary>        /// <param name="fileorder"></param>        /// <param name="fileasc"></param>        public FileSort(FileOrder fileorder, FileAsc fileasc)        {            _fileorder = fileorder;            _fileasc = fileasc;        }        /// <summary>        /// 比较函数        /// </summary>        /// <param name="x"></param>        /// <param name="y"></param>        /// <returns></returns>        public int Compare(object x, object y)        {            FileInfo file1 = x as FileInfo;            FileInfo file2 = y as FileInfo;            FileInfo file3;            if (file1 == null || file2 == null)                throw new ArgumentException("参数不是FileInfo类实例.");            if (_fileasc == FileAsc.Desc)            {                file3 = file1;                file1 = file2;                file2 = file3;            }            switch (_fileorder)            {                case FileOrder.Name:                    return file1.Name.CompareTo(file2.Name);                case FileOrder.Length:                    return file1.Length.CompareTo(file2.Length);                case FileOrder.Extension:                    return file1.Extension.CompareTo(file2.Extension);                case FileOrder.CreationTime:                    return file1.CreationTime.CompareTo(file2.CreationTime);                case FileOrder.LastAccessTime:                    return file1.LastAccessTime.CompareTo(file2.LastAccessTime);                case FileOrder.LastWriteTime:                    return file1.LastWriteTime.CompareTo(file2.LastWriteTime);                default:                    return 0;            }        }    }    /// <summary>    /// 排序依据    /// </summary>    public enum FileOrder    {        /// <summary>        /// 文件名        /// </summary>        Name,        /// <summary>        /// 大小        /// </summary>        Length,        /// <summary>        /// 类型        /// </summary>        Extension,        /// <summary>        /// 创建时间        /// </summary>        CreationTime,        /// <summary>        /// 访问时间        /// </summary>        LastAccessTime,        /// <summary>        /// 修改时间        /// </summary>        LastWriteTime    }    /// <summary>    /// 升序降序    /// </summary>    public enum FileAsc    {        /// <summary>        /// 升序        /// </summary>        Asc,        /// <summary>        /// 降序        /// </summary>        Desc    }