public class VCode : IHttpHandler

     {

         HttpContext context = null;

         public void ProcessRequest(HttpContext context)

         {

             this.context = context;

             CreateVImage(CreateRandomNum());

         }

         #region 创建随机数 CreateRandomNum(int NumCount)

         /// <summary>

         /// 创建随机数

         /// </summary>

         /// <param name="NumCount">条形码上的数字个数</param>

         /// <returns>返回随机数</returns>

         private string CreateRandomNum(int NumCount)

         {

             string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";

             string[] allCharArr = allChar.Split(',');

             string randomNum = "";

             int temp = -;//记录上次随机数的数值,尽量避免产生几个相同的随机数

             Random random = new Random();

             for (int i = ; i < NumCount; i++)

             {

                 if (temp != -)

                 {

                     random = new Random(i * temp * ((int)DateTime.Now.Ticks));

                 }

                 int t = random.Next();

                 if (temp == t)

                 {

                     return CreateRandomNum(NumCount);

                 }

                 temp = t;

                 randomNum += allCharArr[t];

             }

             return randomNum;

         }

         #endregion

         #region 生成验证码图片  CreateVImage(string validateNum)

         /// <summary>

         /// 生成验证码图片 CreateVImage(string validateNum)

         /// </summary>

         /// <param name="validateNum">验证码数字</param>

         private void CreateVImage(string validateNum)

         {

             if (validateNum == null || validateNum.Trim() == string.Empty)

             {

                 return;

             }

             //生成Bitmap图像

             Bitmap image = new Bitmap(validateNum.Length *  + , );

             Graphics g = Graphics.FromImage(image);

             try

             {

                 //随机数生成

                 Random random = new Random();

                 //清空图片背景色,将背景色换为白色

                 g.Clear(Color.White);

                 //画图片的背景线

                 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(Brushes.Beige), x1, y1, x2, y2);

                 }

                 //设置字体

                 Font font = new Font("Arial", , (FontStyle.Bold | FontStyle.Italic));

                 //设置笔刷

                 System.Drawing.Drawing2D.LinearGradientBrush brush =

                     new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

                 //用设置好的字体和笔刷将验证码写到图片上

                 g.DrawString(validateNum, font, brush, , );

                 //画图片上的点

                 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()));

                 }

                 //画图片边框线

                 g.DrawRectangle(new Pen(Color.Silver), , , image.Width, image.Height);

                 //创建一个内存流

                 System.IO.MemoryStream ms = new System.IO.MemoryStream();

                 //将图片保存到指定流中,并指定图片格式

                 image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

                 //清空缓存区所有内容输出

                 context.Response.ClearContent();

                 context.Response.ContentType = "image/jpeg";

                 context.Response.BinaryWrite(ms.ToArray());

             }

             catch (Exception ex)

             {

                 context.Response.Write("异常..."+ex.Message);

             }

             finally

             {

                 //释放资源

                 g.Dispose();

                 image.Dispose();

             }

         }

         #endregion

         public bool IsReusable

         {

             get

             {

                 return false;

             }

         }

     }