/// <summary>    /// 验证码生成类    /// </summary>    public class verify_code : IHttpHandler, IRequiresSessionState    {        public void ProcessRequest(HttpContext context)        {            int codeW = 80;            int codeH = 22;            int fontSize = 16;            string chkCode = string.Empty;            //颜色列表，用于验证码、噪线、噪点             Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };            //字体列表，用于验证码             string[] font = { "Times New Roman", "Verdana", "Arial", "Gungsuh", "Impact" };            //验证码的字符集，去掉了一些容易混淆的字符             char[] character = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘8‘, ‘9‘ };            Random rnd = new Random();            //生成验证码字符串             for (int i = 0; i < 4; i++)            {                chkCode += character[rnd.Next(character.Length)];            }            //写入Session            context.Session["sys_verify_code"] = chkCode;            //创建画布            Bitmap bmp = new Bitmap(codeW, codeH);            Graphics g = Graphics.FromImage(bmp);            g.Clear(Color.White);            //画噪线             for (int i = 0; i < 4; i++)            {                int x1 = rnd.Next(codeW);                int y1 = rnd.Next(codeH);                int x2 = rnd.Next(codeW);                int y2 = rnd.Next(codeH);                Color clr = color[rnd.Next(color.Length)];                g.DrawLine(new Pen(clr), x1, y1, x2, y2);            }            //画验证码字符串             for (int i = 0; i < chkCode.Length; i++)            {                string fnt = font[rnd.Next(font.Length)];                Font ft = new Font(fnt, fontSize);                Color clr = color[rnd.Next(color.Length)];                g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 18 + 2, (float)0);            }            //画噪点             for (int i = 0; i < 100; i++)            {                int x = rnd.Next(bmp.Width);                int y = rnd.Next(bmp.Height);                Color clr = color[rnd.Next(color.Length)];                bmp.SetPixel(x, y, clr);            }            //清除该页输出缓存，设置该页无缓存             context.Response.Buffer = true;            context.Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);            context.Response.Expires = 0;            context.Response.CacheControl = "no-cache";            context.Response.AppendHeader("Pragma", "No-Cache");            //将验证码图片写入内存流，并将其以 "image/Png" 格式输出             MemoryStream ms = new MemoryStream();            try            {                bmp.Save(ms, ImageFormat.Png);                context.Response.ClearContent();                context.Response.ContentType = "image/Png";                context.Response.BinaryWrite(ms.ToArray());            }            finally            {                //显式释放资源                 bmp.Dispose();                g.Dispose();            }        }        public bool IsReusable        {            get            {                return false;            }        }    }

using System;using System.Drawing;using System.Drawing.Imaging;using System.IO;using System.Web;public partial class image : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        string tmp = RndNum(4);        HttpCookie a = new HttpCookie("ImageV", tmp);        Response.Cookies.Add(a);        this.ValidateCode(tmp);    }    private void ValidateCode(string VNum)    {        Bitmap Img = null;        Graphics g = null;        MemoryStream ms = null;        int gheight = VNum.Length * 12;        Img = new Bitmap(gheight, 25);        g = Graphics.FromImage(Img);        //背景颜色        g.Clear(Color.White);        //文字字体        Font f = new Font("Arial Black", 10);        //文字颜色        SolidBrush s = new SolidBrush(Color.Black);        g.DrawString(VNum, f, s, 3, 3);        ms = new MemoryStream();        Img.Save(ms, ImageFormat.Jpeg);        Response.ClearContent();        Response.ContentType = "image/Jpeg";        Response.BinaryWrite(ms.ToArray());        g.Dispose();        Img.Dispose();        Response.End();    }    private string RndNum(int VcodeNum)    {        string Vchar = "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[] VcArray = Vchar.Split(new Char[] { ‘,‘ });        string VNum = "";        int temp = -1;        Random rand = new Random();        for (int i = 1; i < VcodeNum + 1; i++)        {            if (temp != -1)            {                rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));            }            int t = rand.Next(35);            if (temp != -1 && temp == t)            {                return RndNum(VcodeNum);            }            temp = t;            VNum += VcArray[t];        }        return VNum;    }}