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博客园 - boulder

asp.net 利用Cookie实现免登陆(c#) - boulder - 博客园 Md5Encode 算法 javascript浮动图片 - boulder 导出Excel - boulder - 博客园 获取键盘的enter - boulder - 博客园 oracle 的float(b)转 oracle函数(关于处理小数点位数) char、varchar和varchar2的区别(转) - boulder - 博客园 ASP.NET 2.0利用Httphandler实现URL重写(伪URL及伪静态)(转) .net上传文件的限制 电话号码的验证表达式 GridView 在换页时保持CheckBox的选择 在DataList中找到控件 自定义datatable 没有装Express版Sql Server 2005就不能用WebPart ? (转) form表单 input 通过查询系统表得到纵向的表结构 Codebehind CodeFile转 解决flash的虚框问题 - boulder
生成验证码(转) - boulder - 博客园
boulder · 2007-10-31 · via 博客园 - boulder

用户控件的前台
<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="CheckCode.aspx.cs" Inherits="ValidateCode" %>

<!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>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
   
    </div>
    </form>
</body>
</html>
后台:

using System;
using System.Data;
using System.Configuration;
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;
using System.Drawing;

public partial class ValidateCode : System.Web.UI.Page
{
    private void Page_Load(object sender, System.EventArgs e)
    {
        this.CreateCheckCodeImage(GenerateCheckCode());
    }

    #region Web 窗体设计器生成的代码
    override protected void OnInit(EventArgs e)
    {
        //
        // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
        //
        InitializeComponent();
        base.OnInit(e);
    }

    /// <summary>
    /// 设计器支持所需的方法 - 不要使用代码编辑器修改
    /// 此方法的内容。
    /// </summary>
    private void InitializeComponent()
    {
        this.Load += new System.EventHandler(this.Page_Load);
    }
    #endregion

    private string GenerateCheckCode()
    {
        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();
        }

        Response.Cookies.Add(new HttpCookie("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)), 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);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}

一个登陆的验证页面
前台:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" %>

<!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>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            &nbsp;<br />
            <asp:TextBox ID="txtCheckCode" runat="server"></asp:TextBox>
            <img src="CheckCode.aspx" alt="" /><br />
            <asp:Button ID="btnLogin" runat="server" Text="Login" OnClick="btnLogin_Click" /><br />
            <asp:Label ID="lblMessage" runat="server" Text=""></asp:Label></div>
    </form>
</body>
</html>

后台:

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 Login : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnLogin_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;
        }
        else
        {
            Response.Redirect("Welcome.aspx");
        }
    }
}

welcome.aspx的页面

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Welcome.aspx.cs" Inherits="Welcome" %>

<!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>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:Label ID="lblWelcome" runat="server" Text="Welcome to come here"></asp:Label>
   
    </div>
    </form>
</body>
</html>