MVC验证码生成类库

 public class ValidateCode
     {
         /// <summary>
         ///     验证码的最大长度
         /// </summary>
         public int MaxLength
         {
             get { return ; }
         }

         /// <summary>
         ///     验证码的最小长度
         /// </summary>
         public int MinLength
         {
             get { return ; }
         }

         /// <summary>
         ///     生成验证码
         /// </summary>
         /// <param name="length">指定验证码的长度</param>
         /// <returns></returns>
         public string CreateValidateCode(int length)
         {
             var randMembers = new int[length];
             var validateNums = new int[length];
             string validateNumberStr = "";
             //生成起始序列值
             var seekSeek = unchecked((int) DateTime.Now.Ticks);
             var seekRand = new Random(seekSeek);
             int beginSeek = seekRand.Next(, Int32.MaxValue - length*);
             var seeks = new int[length];
             for (int i = ; i < length; i++)
             {
                 beginSeek += ;
                 seeks[i] = beginSeek;
             }
             //生成随机数字
             for (int i = ; i < length; i++)
             {
                 var rand = new Random(seeks[i]);
                 int pownum = *(int) Math.Pow(, length);
                 randMembers[i] = rand.Next(pownum, Int32.MaxValue);
             }
             //抽取随机数字
             for (int i = ; i < length; i++)
             {
                 string numStr = randMembers[i].ToString();
                 int numLength = numStr.Length;
                 var rand = new Random();
                 int numPosition = rand.Next(, numLength - );
                 validateNums[i] = Int32.Parse(numStr.Substring(numPosition, ));
             }
             //生成验证码
             for (int i = ; i < length; i++)
             {
                 validateNumberStr += validateNums[i].ToString();
             }
             return validateNumberStr;
         }

         /// <summary>
         ///     创建验证码的图片
         /// </summary>
         /// <param name="containsPage">要输出到的page对象</param>
         /// <param name="validateNum">验证码</param>
         public byte[] CreateValidateGraphic(string validateCode)
         {
             var image = new Bitmap((int) Math.Ceiling(validateCode.Length*20.0), );
             Graphics g = Graphics.FromImage(image);
             try
             {
                 //生成随机生成器
                 var random = new Random();
                 //清空图片背景色
                 g.Clear(Color.White);
                 //画图片的干扰线
                 for (int i = ; i < ; i++)
                 {
                     int x1 = random.Next(image.Width);
                     int x2 = random.Next(image.Width);
                     int y1 = random.Next(image.Height);
                     int y2 = random.Next(image.Height);
                     g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                 }
                 var font = new Font("Arial", , (FontStyle.Bold | FontStyle.Italic));
                 var brush = new LinearGradientBrush(new Rectangle(, , image.Width, image.Height),
                     Color.Blue, Color.DarkRed, 1.2f, true);
                 g.DrawString(validateCode, font, brush, , );
                 //画图片的前景干扰点
                 for (int i = ; i < ; i++)
                 {
                     int x = random.Next(image.Width);
                     int y = random.Next(image.Height);
                     image.SetPixel(x, y, Color.FromArgb(random.Next()));
                 }
                 //画图片的边框线
                 g.DrawRectangle(new Pen(Color.Silver), , , image.Width - , image.Height - );
                 //保存图片数据
                 var stream = new MemoryStream();
                 image.Save(stream, ImageFormat.Jpeg);
                 //输出图片流
                 return stream.ToArray();
             }
             finally
             {
                 g.Dispose();
                 image.Dispose();
             }
         }

         /// <summary>
         ///     得到验证码图片的长度
         /// </summary>
         /// <param name="validateNumLength">验证码的长度</param>
         /// <returns></returns>
         public static int GetImageWidth(int validateNumLength)
         {
             return (int) (validateNumLength*12.0);
         }

         /// <summary>
         ///     得到验证码的高度
         /// </summary>
         /// <returns></returns>
         public static double GetImageHeight()
         {
             return 22.5;
         }
     }