用Dictionary代替if

        public Dictionary<string, System.Drawing.RotateFlipType> dicRFT = new Dictionary<string, System.Drawing.RotateFlipType>()
        {
            {"90", System.Drawing.RotateFlipType.Rotate90FlipNone},{"180", System.Drawing.RotateFlipType.Rotate180FlipNone},{"270", System.Drawing.RotateFlipType.Rotate270FlipNone}
        };