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【转载】C#实现登录验证码   

2012-10-29 23:38:41|  分类: 默认分类 |  标签: |举报 |字号 订阅

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本文转载自晓晓《C#实现登录验证码 》

最近在开发中遇到要实现登录验证码的功能,在网上借鉴了一下并加以扩展,供大家分享.

代码如下:

///首先新建一个ValidateCode.ashx文件.

using System;

using System.Data;

using System.Web;

using System.Collections;

using System.Web.Services;

using System.Web.Services.Protocols;

using System.Drawing;

namespace WebApplication3

{

    /// <summary>

    /// Summary description for $codebehindclassname$

    /// </summary>

    [WebService(Namespace = "http://tempuri.org/")]

    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

    public class ValidateCode : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            context.Response.Cache.SetCacheability(HttpCacheability.NoCache);///特别注意,如不加,单击验证图片’看不清换一张’,无效果.

            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));///你也可以存到Seesion里.

            return checkCode;

        }

        private void CreateCheckCodeImage(string checkCode, HttpContext context)

        {

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

                return;

            System.Drawing.Bitmap image = new System.Drawing.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();

            }

        }

    }

}

///再实现一个登陆界面

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication3._Default" %>

<!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>登录界面</title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

        用户名:<asp:TextBox ID="txt_user" runat="server"></asp:TextBox>

        <br />

        密 码:<asp:TextBox ID="txt_pwd" runat="server" TextMode="Password"></asp:TextBox><br />

        验证码:

        <asp:TextBox ID="txtCheckCode" runat="server"></asp:TextBox>

        <img src="ValidateCode.ashx" onclick="this.src='ValidateCode.ashx'" title="看不清换一张" />

        <asp:Label ID="lblMessage" runat="server"></asp:Label>

        <br />

        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="登录" /></div>

    </form>

</body>

</html>

///登录页隐藏代码如下:

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;

namespace WebApplication3

{

    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

///如果你的CheckCode是存到Session里的话,代码如下:

            //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

            //    }

            //}

        }

    }

    

}

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