生成一个随机数图片

 

private string GenerateCheckCode()

                  

            {  

                    int number;

                   char code;

                   string checkCode = String.Empty;

        

                  System.Random random = new Random();

        

                   for (int i = 0; i < 5; i++)

                   

                 {

                      number = random.Next();

       

                      if (number % 2 == 0)

                           code = (char)('0' + (char)(number % 10));

                       else

                          code = (char)('A' + (char)(number % 26));

        

                        checkCode += code.ToString();

                    }

   

               /**//**//**////用于客户端校验码比较

               Session["CheckCode"] = checkCode;

  

                return checkCode;

           }

        

       /**//**//**//// <summary>

       /// 将验证码生成图片显示

       /// </summary>

        /// <param name="checkCode"></param>

        private void CreateCheckCodeImage(string checkCode)

        

            {  

            if (checkCode == null || checkCode.Trim() == String.Empty)

                return;

 

            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);

            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 < 25; 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", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

                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()));

                }

 

                /**//**//**////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();

                    }

                }