真爱无限的知识驿站

.net code：

        public void ValidateCode()
        {
            // 在此处放置用户代码以初始化页面
            string vnum;
            vnum = GetByRndNum(6);
            Response.ClearContent(); //需要输出图象信息 要修改HTTP头 
            Response.ContentType = "image/jpeg";
            CreateValidateCode(vnum);
        }
        private void CreateValidateCode(string vnum)
        {
            Bitmap Img = null;
            Graphics g = null;
            Random random = new Random();
            int gheight = vnum.Length * 15;
            Img = new Bitmap(gheight, 24);
            g = Graphics.FromImage(Img);