C# 图形验证码实现登录校验代码

/// <summary>
     /// 生成验证码的类
     /// </summary>
     public class ValidateCode
     {
         /// <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 codeSerial = "2,3,4,5,6,7,8,a,b,c,d,e,f,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";//自定义随机码字符串序列(使用逗号分隔)
             string[] arr = codeSerial.Split(',');

             var validateNumberStr = "";//验证码
             int randValue = -1;//随机数
             Random rand = new Random(unchecked((int)DateTime.Now.Ticks));
             //生成验证码
             for (int i = 0; i < length; i++)
             {
                 randValue = rand.Next(0, arr.Length - 1);
                 validateNumberStr += arr[randValue].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)
         {
             Bitmap image = CreateImageCode(validateCode);
             //保存图片数据
             MemoryStream stream = new MemoryStream();
             image.Save(stream, ImageFormat.Jpeg);
             //输出图片流
             return stream.ToArray();
         }

         /// <summary>
         /// 生成校验码图片
         /// </summary>
         /// <param name="code"></param>
         /// <returns></returns>
         public Bitmap CreateImageCode(string code)
         {
             int Length = code.Length;//验证码长度

             int fSize = 40;//验证码字体大小
             int FontSize = 40;
             int Padding = 2;//边框补
             int fWidth = fSize + Padding;

             int imageWidth = (int)(code.Length * fWidth) + 4 + Padding * 2;
             int imageHeight = fSize * 2 + Padding;

             System.Drawing.Bitmap image = new System.Drawing.Bitmap(imageWidth, imageHeight);

             Graphics g = Graphics.FromImage(image);

             Color BackgroundColor = Color.White;//自定义背景颜色
             Color ChaosColor = Color.LightGray;//噪点颜色
             Color[] Colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };//自定义随机颜色数组

             string[] Fonts = { "Arial", "Georgia" };//自定义字体数组

             bool chaos = true;//是否输出噪点

             g.Clear(BackgroundColor);

             Random rand = new Random();

             //给背景添加随机生成的燥点
             if (chaos)
             {
                 Pen pen = new Pen(ChaosColor, 0);
                 int c = Length * 10;

                 for (int i = 0; i < c; i++)
                 {
                     int x = rand.Next(image.Width);
                     int y = rand.Next(image.Height);

                     g.DrawRectangle(pen, x, y, 1, 1);
                 }
             }

             int left = 0, top = 0, top1 = 1, top2 = 1;

             int n1 = (imageHeight - FontSize - Padding * 2);
             int n2 = n1 / 4;
             top1 = n2;
             top2 = n2 * 2;

             Font f;
             Brush b;

             int cindex, findex;

             //随机字体和颜色的验证码字符
             for (int i = 0; i < code.Length; i++)
             {
                 cindex = rand.Next(Colors.Length - 1);
                 findex = rand.Next(Fonts.Length - 1);

                 f = new System.Drawing.Font(Fonts[findex], fSize, System.Drawing.FontStyle.Bold);
                 b = new System.Drawing.SolidBrush(Colors[cindex]);

                 if (i % 2 == 1)
                 {
                     top = top2;
                 }
                 else
                 {
                     top = top1;
                 }

                 left = i * fWidth;

                 g.DrawString(code.Substring(i, 1), f, b, left, top);
             }

             //画一个边框 边框颜色为Color.Gainsboro
             g.DrawRectangle(new Pen(Color.Gainsboro, 0), 0, 0, image.Width - 1, image.Height - 1);
             g.Dispose();

             //产生波形（Add By 51aspx.com）
             image = TwistImage(image, true, 8, 4);

             return image;
         }

         private const double PI = 3.1415926535897932384626433832795;
         private const double PI2 = 6.283185307179586476925286766559;

         /// <summary>
         /// 正弦曲线Wave扭曲图片（Edit By 51aspx.com）
         /// </summary>
         /// <param name="srcBmp">图片路径</param>
         /// <param name="bXDir">如果扭曲则选择为True</param>
         /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param>
         /// <param name="dPhase">波形的起始相位，取值区间[0-2*PI)</param>
         /// <returns></returns>
         public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
         {
             System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

             // 将位图背景填充为白色
             System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);
             graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);
             graph.Dispose();

             double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

             for (int i = 0; i < destBmp.Width; i++)
             {
                 for (int j = 0; j < destBmp.Height; j++)
                 {
                     double dx = 0;
                     dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;
                     dx += dPhase;
                     double dy = Math.Sin(dx);

                     // 取得当前点的颜色
                     int nOldX = 0, nOldY = 0;
                     nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
                     nOldY = bXDir ? j : j + (int)(dy * dMultValue);

                     System.Drawing.Color color = srcBmp.GetPixel(i, j);
                     if (nOldX >= 0 && nOldX < destBmp.Width
                      && nOldY >= 0 && nOldY < destBmp.Height)
                     {
                         destBmp.SetPixel(nOldX, nOldY, color);
                     }
                 }
             }

             return destBmp;
         }
     }