验证码

1、新建CheckCodeImageExt.aspx

View Code
using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;



namespace CheckCode

{

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

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            CreateCheckCodeImage(GenarateCheckCode());

        }

        private string GenarateCheckCode()  

        {

            int number;

            char code;

            string CheckCode = string.Empty;



            System.Random random = new Random();

            for (int i = 0; i < 5; i++)

            {

                number = random.Next();

                if (number % 2 == 0)

                    code = (char)('0' + (char)(number % 10));

                else

                    code = (char)('A' + (char)(number % 26));

                CheckCode += code.ToString();

            }

            Session["CheckCode"] = CheckCode;

            return CheckCode;

        }



        private void CreateCheckCodeImage(string checkCode)

        {

            if (checkCode == null || checkCode.Trim() == string.Empty)

                return;



            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling(checkCode.Length * 12.5), 24);//宽度,高度

            Graphics g = Graphics.FromImage(image);



            try

            {

                Random random = new Random();

                //清空图片背景色,并用白色填充

                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);

                Response.ClearContent();

                Response.ContentType = "image/Gif";

                Response.BinaryWrite(ms.ToArray());

            }

            catch

            {

                g.Dispose();

                image.Dispose();

            }

        }

    }

}

2、新建登录Logon.aspx

View Code
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Logon.aspx.cs" Inherits="CheckCode.Logon" %>



<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">



<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title></title>

    <script type="text/javascript">

        function reload() {

            var code = document.getElementById('imgCode');

            code.src += '?';

        }

    </script>

</head>

<body>

    <form id="form1" runat="server">

    <div>

        <div style=" height:200px;"></div>

        <div style="float:left; width:30%; height:100px;"></div>

        <div style="float:left; width:40%; height:100px;">

            <div><img src="CheckCodeImageExt.aspx" alt="checkCode" id="imgCode" onclick="reload();" title="点击刷新" /></div>

        </div>

    </div>

    </form>

</body>

</html>

 

img.src = img.src+'?';这一句使服务器重新生成图片, 问号的作用是忽悠浏览器, 不要让浏览器缓存

OK....

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