using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Text;using System.Drawing.Imaging;using System.IO;using System.Drawing; public partial class image : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        string tep = generateCheckCode(4);        HttpCookie a = new HttpCookie("image",tep);        Response.Cookies.Add(a);        //this.validatecode(tep);        this.CreateCheckCodeImage(tep);     }    //生成随机数    private string generateCheckCode(int length)    {        char[] constant ={ '0','1', '2', '3', '4', '5', '6', '7', '8', '9',             'a', 'b', 'c', 'd', 'e','f','g','h','i','j','k','u','m','l','o','p','q','r','s','t','u','v','w','x','y','z',        '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',};         StringBuilder checkcodes = new StringBuilder(62);        Random rd = new Random();        for (int i = 0; i < length; i++)        {            checkcodes.Append(constant[rd.Next(62)]);        }        return checkcodes.ToString();    }     //生成验证码图片    //方法一    private void validatecode(string code)    {        Bitmap img = null;        Graphics g = null;        MemoryStream ms = null;         int gwidth = code.Length * 12;        img = new Bitmap(gwidth, 25);        g = Graphics.FromImage(img);        //背景颜色        g.Clear(Color.White);        Font f = new Font("Arial Black", 10); //文字字体        SolidBrush s = new SolidBrush(Color.Black); //文字颜色         g.DrawString(code, f, s,3,3);        ms = new MemoryStream();        img.Save(ms, ImageFormat.Jpeg);        Response.ClearContent();        Response.ContentType = "image/jpge";        Response.BinaryWrite(ms.ToArray());        g.Dispose();        img.Dispose();        Response.End();     }    //方法二    public 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();        }    }}     要在 a.aspx 页面中生成图片验证码，在a 页面中放一个image 图像控件，在pageload中 写入它的imageurl，如上面的代码页面为b.aspx 则为 imageurl=b.aspx

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