ASP.NET验证码(非常好用)

ASP.NET验证码(非常好用)using System;

using System.Collections.Generic;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.IO;

using System.Drawing.Imaging;



namespace Dachie

{

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

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            //验证码长度

            int CodeSize = 5;

            //生成验证码值

            string Code = CreateValidateNumber(CodeSize);

            //创建验证码

            CreateValidateGraphic(this, Code);

        }

        /// <summary>

        /// 得到验证码图片的长度

        /// </summary>

        /// <param name="validateNumLength">验证码的长度</param>

        /// <returns></returns>

        public static int GetImageWidth(int validateNumLength)

        {

            return (int)(validateNumLength * 12.5);

        }

        /// <summary>

        /// 得到验证码的高度

        /// </summary>

        /// <returns></returns>

        public static double GetImageHeight()

        {

            return 22.5;

        }

        /// <summary>

        /// 验证码的最大长度

        /// </summary>

        public int MaxLength

        {

            get { return 10; }

        }

        /// <summary>

        /// 验证码的最小长度

        /// </summary>

        public int MinLength

        {

            get { return 1; }

        }

        /// <summary>

        /// 生成验证码

        /// </summary>

        /// <param name="length">指定验证码的长度</param>

        /// <returns></returns>

        public string CreateValidateNumber(int length)

        {

            int[] randMembers = new int[length];

            int[] validateNums = new int[length];

            string validateNumberStr = "";

            //生成起始序列值

            int seekSeek = unchecked((int)DateTime.Now.Ticks);

            Random seekRand = new Random(seekSeek);

            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);

            int[] seeks = new int[length];

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

            {

                beginSeek += 10000;

                seeks[i] = beginSeek;

            }

            //生成随机数字

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

            {

                Random rand = new Random(seeks[i]);

                int pownum = 1 * (int)Math.Pow(10, length);

                randMembers[i] = rand.Next(pownum, Int32.MaxValue);

            }

            //抽取随机数字

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

            {

                string numStr = randMembers[i].ToString();

                int numLength = numStr.Length;

                Random rand = new Random();

                int numPosition = rand.Next(0, numLength - 1);

                validateNums[i] = Int32.Parse(Math.Abs(Int64.Parse(numStr)).ToString().Substring(numPosition, 1));

            }

            //生成验证码

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

            {

                validateNumberStr += validateNums[i].ToString();

            }

            return validateNumberStr;

        }

        /// <summary>

        /// 创建验证码的图片

        /// </summary>

        /// <param name="containsPage">要输出到的page对象</param>

        /// <param name="validateNum">验证码</param>

        public void CreateValidateGraphic(Page containsPage, string validateNum)

        {

            Bitmap image = new Bitmap((int)Math.Ceiling(validateNum.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);

                //画图片的干扰线

                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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));

                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),

                 Color.Blue, Color.DarkRed, 1.2f, true);

                g.DrawString(validateNum, font, brush, 3, 2);

                //画图片的前景干扰点

                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);

                //保存图片数据

                MemoryStream stream = new MemoryStream();

                image.Save(stream, ImageFormat.Jpeg);

                //输出图片

                containsPage.Response.Clear();

                containsPage.Response.ContentType = "image/jpeg";

                containsPage.Response.BinaryWrite(stream.ToArray());

            }

            finally

            {

                g.Dispose();

                image.Dispose();

            }

        }

    }

}