随机验证码.ashx

ValidateCode.ashx

<%@ WebHandler Language="C#" class="ValidateCode" %>

using System;
using System.Collections;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;
using System.Drawing.Drawing2D;
using System.Drawing;

    public class ValidateCode : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
            this.CreateCheckCodeImage(GenerateCheckCode(context), context);
        }
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
        private string GenerateCheckCode(HttpContext context)
        {
            int number;
            char code;
            string checkCode = String.Empty;

            System.Random random = new Random();

            for (int i = 0; i < 6; i++)
            {
                number = random.Next();

                if (number % 2 == 0)
                    code = (char)(‘0‘ + (char)(number % 10));
                else if (number % 3 == 0)
                    code = (char)(‘A‘ + (char)(number % 26));
                else
                    code = (char)(‘a‘ + (char)(number % 26));
                checkCode += code.ToString();
            }

            context.Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
            //也可以存到Seesion里．        
            //context.Session["CheckCode"] = checkCode;   
            return checkCode;
        }
        private void CreateCheckCodeImage(string checkCode, HttpContext context)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;
            Bitmap image = new 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);
                context.Response.ClearContent();
                context.Response.ContentType = "image/Gif";
                context.Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }

        }
    }
}

页面:

       <img src="ValidateCode.ashx" title="看不清？点击刷新" style="cursor:pointer" onclick="this.src=‘ValidateCode.ashx?_=‘+Math.random()">     

后台代码:

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;

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

   {        

protected void Page_Load(object sender, EventArgs e)        

{

        }

        protected void Button1_Click(object sender, EventArgs e)  

       {         

    if (Request.Cookies["CheckCode"] == null)        

     {           

      lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";          

       lblMessage.Visible = true;       

          return;           

  }

            if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0)     

        {          

       lblMessage.Text = "验证码错误，请输入正确的验证码。";    

             lblMessage.Visible = true;      

           return;       

      }

 //在这执行下一步     

                                //CheckCode是存到Session里的       

      //if (Session["CheckCode"] != null)             //{             //    if (String.Compare(Session["CheckCode"].ToString(), txtCheckCode.Text.Trim(), true) != 0)             //    {             //        lblMessage.Text = "验证码错误，请输入正确的验证码。";             //        lblMessage.Visible = true;             //        return;             //    }             //    else             //    {//在这执行下一步             //    }             //}         }     }