控制器中的                               

public ActionResult valideCode() {

            //创建长的为5的字符串

            string strvalideCode = Title.GetRandomCode(5);

            //将验证码传递到服务器以便验证验证码是否正确

            Session["ValideCode"] = strvalideCode;

            //将生成的字符串转换为字符串，二进制数组接收

            byte[] ImgValideCode = Title.CreateImage(strvalideCode);

            return File(ImgValideCode, "image/jpeg");

        }

验证码的自定义类

/// <summary>

        /// 获得随机字符串

        /// </summary>

        /// <param name="intLength">随机数的长度</param>

        /// <returns>随机数字符串</returns>

        public static string GetRandomCode(int intLength)

        {

            /*产生数字和密码混合的随机数*/

            string strReturn = string.Empty;

            Random random = new Random();//随机数

            for (int i = 0; i < intLength; i++)

            {

                char cRerult;

                int intRandom = random.Next();//产生一个非负随机整数

                /*根据当前随机数来确定字符串*/

                //intRandom % 3 获取的是intRandom/3 得到的余数

                if (intRandom % 3 == 0)

                {

                    //产生数字

                    //位数来产生数字

                    cRerult = (char)(0x30 + (intRandom % 10));

                }

                else if (intRandom % 3 == 1)

                {

                    //位数产生大写字母:大写字符 65-97 A 65

                    //68 D  25 Z

                    cRerult = (char)(0x41 + (intRandom % 0x1a));

                }

                else

                {

                    //余数为2

                    //产生小写字母 98-116

                    cRerult = (char)(0x61 + (intRandom % 0x1a));

                }

                strReturn += cRerult.ToString();

            }

            return strReturn;

        }

        /// <summary>

        /// 根据字符串创建验证码 返回值：二进制数组

        /// </summary>

        /// <param name="strRandom">字符串</param>

        /// <returns>图片</returns>

        public static byte[] CreateImage(string strRandom)

        {

            //新增图片

            Bitmap newBitmap = new Bitmap(strRandom.Length * 20, 30);

            Graphics g = Graphics.FromImage(newBitmap);

            g.Clear(Color.White);

            //在图片上绘制文字

            SolidBrush solidBrush = new SolidBrush(Color.Red);

            g.DrawString(strRandom, new Font("Aril", 17), solidBrush, 12, 1);

            //在图片上绘制干扰线

            Random random = new Random();

            for (int i = 0; i < 10; i++)

            {

                //产生一条线，并绘制到画布。 起始点（x,y）  总结点

                int x1 = random.Next(newBitmap.Width);

                int y1 = random.Next(newBitmap.Height);

                int x2 = random.Next(newBitmap.Width);

                int y2 = random.Next(newBitmap.Height);

                g.DrawLine(new Pen(Color.DarkGray), x1, y1, x2, y2);

            }

            //绘制图片的前景干扰点

            for (int i = 0; i < 100; i++)

            {

                int x = random.Next(newBitmap.Width);

                int y = random.Next(newBitmap.Height);

                newBitmap.SetPixel(x, y, Color.FromArgb(random.Next()));

            }

            //在最外边绘制边框

            g.DrawRectangle(new Pen(Color.Blue), 0, 0, newBitmap.Width, newBitmap.Height);

            g.DrawRectangle(new Pen(Color.Blue), -1, -1, newBitmap.Width, newBitmap.Height);

            //将图转保存到内存流中

            MemoryStream ms = new MemoryStream();

            newBitmap.Save(ms, ImageFormat.Jpeg);

            return ms.ToArray();//将流内容写入byte数组返回