ASP.NET制作验证码

ASP.NET验证码

using System;

using System.IO;

using System.Drawing;

using System.Drawing.Imaging;

using System.Text;

using System.Collections;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

namespace ykt_qzx

{

    public partial class sj : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            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", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };

            //验证码的字符集，去掉了一些容易混淆的字符 

            char[] character ={ '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };

            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)];

            }

            Bitmap bmp = new Bitmap(100, 40);

            Graphics g = Graphics.FromImage(bmp);

            g.Clear(Color.White);

            //画噪线 

            for (int i = 0; i < 10; i++)

            {

                int x1 = rnd.Next(100);

                int y1 = rnd.Next(40);

                int x2 = rnd.Next(100);

                int y2 = rnd.Next(40);

                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, 18);

                Color clr = color[rnd.Next(color.Length)];

                g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)8);

            }

            //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 

            Response.Buffer = true;

            Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);

            Response.Expires = 0;

            Response.CacheControl = "no-cache";

            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);

                Response.ClearContent();

                Response.ContentType = "image/Png";

                Response.BinaryWrite(ms.ToArray());

            }

            finally

            {

                //显式释放资源 

                bmp.Dispose();

                g.Dispose();

            }

        }

    }

}

这个验证有一定弊端，望使用者可以根据自己的观点在使用时合理改变。