收藏一段小的.net下的验证码片段

收藏一段小的.net下的验证码片段，以供以后参考。

 protected void Page_Load(object sender, EventArgs e)
    {
         //先产生数字串
         string checkCode = th***CreateRandomCode(6);
        //用session保存
         Session["CheckCode"] = checkCode;
      //作图
        CreateImage(checkCode);
       
    }
    private void CreateImage(string checkCode)
    {
        Sy***m.Drawing.Bitmap image = new Sy***m.Drawing.Bitmap(Co***rt.ToInt32(Ma***Ceiling((decimal)(ch***Code.Length * 14))), 22);
        Graphics g = Gr***ics.FromImage(image);
       

        try
        {
          
            Random random = new Random();
            g.Clear(Co***.AliceBlue);
           
            for (int i = 0; i < 25; i++)
            {
                int x1 = ra***m.Next(im***.Width);
                int x2 = ra***m.Next(im***.Width);
                int y1 = ra***m.Next(im***.Height);
                int y2 = ra***m.Next(im***.Height);

                g.***wLine(new Pen(Co***.Silver), x1, y1, x2, y2);
            }

            Font font = new Sy***m.Drawing.Font("Comic Sans MS", 12, Sy***m.Drawing.FontStyle.Bold);
            Sy***m.Drawing.Drawing2D.LinearGradientBrush brush = new Sy***m.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, im***.Width, im***.Height), Co***.Blue, Co***.DarkRed, 1.2f, true);
            g.***wString(checkCode, font, new SolidBrush(Co***.Red), 2, 2);

           
            for (int i = 0; i < 100; i++)
            {
                int x = ra***m.Next(im***.Width);
                int y = ra***m.Next(im***.Height);

                im***.SetPixel(x, y, Co***.FromArgb(ra***m.Next()));
            }

            g.***wRectangle(new Pen(Co***.Silver), 0, 0, im***.Width - 1, im***.Height - 1);

            Sy***m.IO.MemoryStream ms = new Sy***m.IO.MemoryStream();
            im***.Save(ms, Sy***m.Drawing.Imaging.ImageFormat.Gif);
            Re***nse.ClearContent();
            Re***nse.ContentType = "image/Gif";
            Re***nse.BinaryWrite(ms***Array());
        }
        finally
        {
            g.***pose();
            im***.Dispose();
        }
    }

    public string CreateRandomCode(int codeCount)
    {
        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[] allCharArray = al***ar.Split(',');
        string randomCode = "";
        int temp = -1;

        Random rand = new Random();
        for (int i = 0; i < codeCount; i++)
        {
            if (temp != -1)
            {
                rand = new Random(i * temp * ((int)Da***ime.Now.Ticks));
            }
            int t = ra***Next(36);
            if (temp != -1 && temp == t)
            {
                return CreateRandomCode(codeCount);
            }
            temp = t;
            randomCode += allCharArray[t];
        }
        return randomCode;
    }

http://www.cnblogs.com/jackyrong/archive/2006/08/25/486281.html