项目中验证码的使用

aspx类的验证码处理程序，随后还会记录一般程序的的验证码类

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using Maticsoft.Common;
namespace Maticsoft.Web
{
    public partial class ValidateCode : System.Web.UI.Page
    {
        private static char[] constant =    //声明一个静态的字符数组，验证码从这里面随机的取
      {   
        '1','2','3','4','5','6','7','8','9',
        'a','b','c','d','e','f','g','h','i','j','k','l','m','n','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'   
      };
        private void Page_Load(object sender, System.EventArgs e)
        {
            string checkCode = CreateNumber(4);
          //  Session["validateCode"] = checkCode.ToLower()
            Common_Sesson.Add("validateCode", checkCode.ToLower());
            CreateCheckCodeImage(checkCode);
        }

        #region 画出图片并显示到调用这个方法的画布上
        private void CreateCheckCodeImage(string code)
        {
            var imageCode = new System.Drawing.Bitmap((int)Math.Ceiling((code.Length * 12.5)), 23); //定义图片的宽度和高度
            var g = Graphics.FromImage(imageCode);  //加载图片到画布上

            HttpContext.Current.Session["Code_Char"] = code; //将验证码写入到session中实现验证

            try
            {
                var random = new Random();
                g.Clear(Color.White); //清空图片背景色

                //画图片的背景噪音线
                for (int i = 0; i < 25; i++)
                {
                    var x1 = random.Next(imageCode.Width);
                    var x2 = random.Next(imageCode.Width);
                    var y1 = random.Next(imageCode.Height);
                    var y2 = random.Next(imageCode.Height);

                    g.DrawLine(new Pen(Color.Silver), new Point(x1, y1), new Point(x2, y2));
                }

                var font = new System.Drawing.Font("Arial", 12F, System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic);
                var brush = new System.Drawing.Drawing2D.LinearGradientBrush(
                    new Rectangle(0, 0, imageCode.Width, imageCode.Height),
                    Color.Blue, Color.DarkRed, 1.2F, true);
                g.DrawString(code, font, brush, 2, 2);

                //画图片的前景噪音点
                for (int i = 0; i < 100; i++)
                {
                    var x = random.Next(imageCode.Width);
                    var y = random.Next(imageCode.Height);
                    imageCode.SetPixel(x, y, Color.FromArgb(random.Next()));
                }

                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, imageCode.Width - 1, imageCode.Height - 1);
                var ms = new System.IO.MemoryStream();
                imageCode.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

                HttpContext.Current.Response.ClearContent();
                HttpContext.Current.Response.ContentType = "image/jpg";
                HttpContext.Current.Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                imageCode.Dispose();
            }
        }
        #endregion
        #region 生成0——60的随机数
        private static string CreateNumber(int n) //n表示产生字符串的长度
        {
            string str = "";
            System.Text.StringBuilder newRandom = new System.Text.StringBuilder(60);
            Random rd = new Random();
            while (n-- > 0)
            {
                str = str + constant[rd.Next(60)];
            }
            return str;
        }
        #endregion


    }
}

前台的视图代码

<p>验证码： <input type="text" id="yzm" style=" 100px"/>
         <img title="看不清？" style=" cursor:pointer ;vertical-align:middle" width="70px"  src="ValidateCode.aspx"   onclick="this.src='ValidateCode.aspx?r='+Math.random()" />
      </p>

出错更换的js代码

                  $("#yzm").next().attr("src", "ValidateCode.aspx?r=" + Math.random());