汉字的验证码

public partial class KeleyiImage : System.Web.UI.Page    

　　{

        protected void Page_Load(object sender, EventArgs e)

        {

            this.CreateCheckCodeImage(GenerateCheckCode());

        }

        private string GenerateCheckCode()

        {

            //int number;

            //char code;

            string checkCode = String.Empty;

            System.Random random = new Random();  

           Encoding gb = Encoding.GetEncoding("gb2312");

            //调用函数产生4个随机中文汉字编码 柯乐义  

           object[] bytes = CreateRegionCode(6);

            //根据汉字编码的字节数组解码出中文汉字  

           string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));

            string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));

            string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));

            string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));

            //输出的控制台  

           checkCode = str1 + str2 + str3 + str4;   

          Response.Cookies.Add(new HttpCookie("ValidCode", checkCode));    

          return checkCode;

        }

        #region 产生波形滤镜效果

        private static object[] CreateRegionCode(int strlength)

        {

            //定义一个字符串数组储存汉字编码的组成元素

            string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

            Random rnd = new Random();

            //定义一个object数组用来

            object[] bytes = new object[strlength];

            /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中

            每个汉字有四个区位码组成

            区位码第1位和区位码第2位作为字节数组第一个元素

            区位码第3位和区位码第4位作为字节数组第二个元素

            */

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

            {  

               //区位码第1位

                int r1 = rnd.Next(11, 14);   

              string str_r1 = rBase[r1].Trim();

                //区位码第2位

                rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i)//更换随机数发生器的

                //种子避免产生重复值

                int r2;

                if (r1 == 13)

                {

                    r2 = rnd.Next(0, 7);

                }

                else  

               {

                    r2 = rnd.Next(0, 16);

                }

                string str_r2 = rBase[r2].Trim();

                //区位码第3位

                rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);

                int r3 = rnd.Next(10, 16);

                string str_r3 = rBase[r3].Trim();

                //区位码第4位  

               rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);

                int r4;

                if (r3 == 10)

                {

                    r4 = rnd.Next(1, 16);  

               }

                else if (r3 == 15)

                {  

                   r4 = rnd.Next(0, 15);

                }

                else

                {

                    r4 = rnd.Next(0, 16);  

               }

                string str_r4 = rBase[r4].Trim();

                //定义两个字节变量存储产生的随机汉字区位码

                byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);

                byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

                //将两个字节变量存储在字节数组中  

               byte[] str_r = new byte[] { byte1, byte2 };

                //将产生的一个汉字的字节数组放入object数组中

                bytes.SetValue(str_r, i);  

           }

            return bytes;

        }

        private const double PI = 3.1415926535897932384626433832795;

        private const double PI2 = 6.283185307179586476925286766559;

        private 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;

        }

        #endregion  

       private void CreateCheckCodeImage(string checkCode)  

       {

            if (checkCode == null)

                return;

            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 27.0)), 25);

            Graphics g = Graphics.FromImage(image);

            try             {                 //生成随机生成器                 Random random = new Random();                 //清空图片背景色                 g.Clear(Color.White);                 //画图片的背景噪音线                 for (int i = 0; i < 12; 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);                 }                 //Font font = new System.Drawing.Font("Arial", 16, (System.Drawing.FontStyle.Bold 　 System.Drawing.FontStyle.Italic));                 Font font = new System.Drawing.Font("楷体_GB2312", 16, (System.Drawing.FontStyle.Bold));                 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);                 g.DrawString(checkCode, font, brush, 2, 2);                 //画图片的前景噪音点                 for (int i = 0; i < 100; i++)                 {                     int x = random.Next(image.Width);                     int y = random.Next(image.Height);                     image.SetPixel(x, y, Color.FromArgb(random.Next()));                 }                 //image = TwistImage(image, true, 3, 1);                 //画图片的波形滤镜效果                 //画图片的边框线                 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);                 System.IO.MemoryStream ms = new System.IO.MemoryStream();                 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);                 Response.ClearContent();                 Response.ContentType = "image/Gif";                 Response.BinaryWrite(ms.ToArray());             }             finally             {                 g.Dispose();                 image.Dispose();             }         }     }