带验证码登录

随机生成验证码ValidateCode.ashx

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

using System;
using System.Web;
using System.Drawing;
using System.Web.SessionState;
//一般处理程序中使用session，必须实现一个接口
public class ValidateCode : IHttpHandler,IRequiresSessionState {

    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "image/jpeg";
        string code = GetRndStr();  //生成4个随机的字符
        
        //记录生成的验证码
        context.Session["code"] = code;
        
        using (Bitmap img = CreateImages(code, "ch"))
        {
            img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
    /// <summary>
    /// 数字随机数
    /// </summary>
    /// <returns></returns>
    private string GetRndNum()
    {
        string code = string.Empty;
        Random random = new Random();
        for (int i = 0; i < 4; i++)
        {
            code += random.Next(9);
        }
        return code;
    }
    /// <summary>
    ///  英文随机
    /// </summary>
    /// <returns></returns>
    private string GetRndStr()
    {
        string Vchar = "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";
        string[] VcArray = Vchar.Split(',');
        string checkCode = string.Empty;
        Random rand = new Random();
        for (int i = 0; i < 4; i++)
        {
            int t = rand.Next(VcArray.Length);
            checkCode += VcArray[t];
        }
        return checkCode;
    }
    /// <summary>
    /// 中文随机
    /// </summary>
    /// <returns></returns>
    private string GetRndCh()
    {
        System.Text.Encoding gb = System.Text.Encoding.Default;//获取GB2312编码页（表）
        object[] bytes = CreateRegionCode(4);//生4个随机中文汉字编码
        string[] str = new string[4];
        System.Text.StringBuilder sb = new System.Text.StringBuilder();
        for (int i = 0; i < 4; i++)
        {
            //根据汉字编码的字节数组解码出中文汉字
            str[i] = gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));
            sb.Append(str[i].ToString());
        }
        return sb.ToString();
    }
    /// <summary>
    /// 产生随机中文字符
    /// </summary>
    /// <param name="strlength"></param>
    /// <returns></returns>
    private static object[] CreateRegionCode(int strlength)
    {
        //定义一个字符串数组储存汉字编码的组成元素
        string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
        Random rnd = new Random();
        object[] bytes = new object[strlength];

        for (int i = 0; i < strlength; i++)
        {
            //区位码第1位
            int r1 = rnd.Next(11, 14);
            string str_r1 = rBase[r1].Trim();
            //区位码第2位
            rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);
            int r2;
            if (r1 == 13)
            {
                r2 = rnd.Next(0, 7);
            }
            else
            {
                r2 = rnd.Next(0, 16);
            }
            string str_r2 = rBase[r2].Trim();

            //区位码第3位
            rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机种子
            int r3 = rnd.Next(10, 16);
            string str_r3 = rBase[r3].Trim();

            //区位码第4位
            rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
            int r4;
            if (r3 == 10)
            {
                r4 = rnd.Next(1, 16);
            }
            else if (r3 == 15)
            {
                r4 = rnd.Next(0, 15);
            }
            else
            {
                r4 = rnd.Next(0, 16);
            }
            string str_r4 = rBase[r4].Trim();
            //定义两个字节变量存储产生的随机汉字区位码
            byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
            byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

            //将两个字节变量存储在字节数组中
            byte[] str_r = new byte[] { byte1, byte2 };

            //将产生的一个汉字的字节数组放入object数组中
            bytes.SetValue(str_r, i);
        }
        return bytes;
    }
    /// <summary>
    /// 画图片的背景图+干扰线 
    /// </summary>
    /// <param name="checkCode"></param>
    /// <returns></returns>
    private Bitmap CreateImages(string checkCode, string type)
    {
        int step = 0;
        if (type == "ch")
        {
            step = 5;//中文字符，边界值做大
        }
        int iwidth = (int)(checkCode.Length * (13 + step));
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 33);
        Graphics g = Graphics.FromImage(image);
        g.Clear(Color.White);//清除背景色
        Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };//定义随机颜色
        string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
        Random rand = new Random();

        for (int i = 0; i < 50; i++)
        {
            int x1 = rand.Next(image.Width);
            int x2 = rand.Next(image.Width);
            int y1 = rand.Next(image.Height);
            int y2 = rand.Next(image.Height);
            g.DrawLine(new Pen(Color.LightGray, 1), x1, y1, x2, y2);//根据坐标画线
        }

        for (int i = 0; i < checkCode.Length; i++)
        {
            int cindex = rand.Next(7);
            int findex = rand.Next(5);

            Font f = new System.Drawing.Font(font[findex], 15, System.Drawing.FontStyle.Bold);
            Brush b = new System.Drawing.SolidBrush(c[cindex]);
            int ii = 4;
            if ((i + 1) % 2 == 0)
            {
                ii = 2;
            }
            g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * (12 + step)), ii);

        }
        g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        return image;
    }
}

 登录模块设计sidebar.ascx

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="sidebar.ascx.cs" Inherits="Web.UserControl.sidebar" %>
        <div class="bar notice">
                <div class="title ">公告</div>
                <div class="c">
                    <p>第一次登陆请尽快修改密码，默认密码是您生日的后六位</p>
                </div>
            </div>

            <div class="bar login">
                <div class="title">登陆</div>
                <div class="c">
                    <table>
                        <tr>
                            <td style=" 500px">类  型：</td>
                            <td style=" 85%">
                                <asp:DropDownList ID="ddl" runat="server">
                                    <asp:ListItem Value="1">学生</asp:ListItem>
                                    <asp:ListItem Value="2">老师</asp:ListItem>
                                </asp:DropDownList>
                            </td>
                        </tr>
                        <tr>
                            <td>账  号：</td>
                            <td>
                                <asp:TextBox ID="txtNo" Width="80" runat="server"></asp:TextBox>
                            </td>
                        </tr>
                        <tr>
                            <td>密  码：</td>
                            <td>
                                <asp:TextBox ID="txtPwd" Width="80" runat="server" TextMode="Password"></asp:TextBox>
                            </td>
                        </tr>
                        <tr>
                            <td>验证码：</td>
                            <td>
                                <asp:TextBox ID="txtCode" style="vertical-align:middle" Width="30" runat="server"></asp:TextBox><img title="看不清？" style=" cursor:pointer ;vertical-align:middle" width="45px" src="../ValidateCode.ashx" onclick="this.src='../ValidateCode.ashx?_='+Math.random()" />
                            </td>
                        </tr>
                        <tr>
                            <td colspan="2" align="center">
                                <asp:Button ID="btnLogin" runat="server" Text="登  陆" OnClick="btnLogin_Click" />
                                <asp:Label ID="lblMsg" runat="server" ForeColor="Red"></asp:Label>
                            </td>
                        </tr>
                    </table>
                </div>
            </div>

 sidebar.ascx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Web.UserControl
{
    public partial class sidebar : System.Web.UI.UserControl
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void btnLogin_Click(object sender, EventArgs e)
        {

            //学生  1  老师 2
            string type = ddl.SelectedValue;
            string no = txtNo.Text.Trim();
            string pwd = txtPwd.Text.Trim();
            //md5加密
            pwd =   Common.GetMd5(pwd);


            string code = txtCode.Text.Trim();
             
            //验证码正确    因为session有过期失效的问题，
            if (Session["code"] != null &&  code.ToLower() == Session["code"].ToString().ToLower())
            {
                //
                Session.Remove("code");
                string msg;
                //学生
                if (type == "1")
                { //判断用户名密码是否正确
                    ItcastOCSS.BLL.Student bll = new ItcastOCSS.BLL.Student();
                    ItcastOCSS.Model.Student stu = new ItcastOCSS.Model.Student();
                    if (bll.Login(no, pwd, out msg, out stu))
                    {
                        //记录登陆成功的状态
                        Session["user"] = stu;
                        //跳转
                        Response.Redirect("Student/Index.aspx");
                    }
                    lblMsg.Text = msg;
                }
                else if (type == "2")
                { 
                    //老师
                    ItcastOCSS.BLL.Teacher bll = new ItcastOCSS.BLL.Teacher();
                    ItcastOCSS.Model.Teacher tea = new ItcastOCSS.Model.Teacher();
                    if (bll.Login(no, pwd, out msg, out tea))
                    {
                        Session["user"] = tea;
                        //跳转
                        if (tea.TIsAdmin == 1)
                        {
                            //管理员
                            Response.Redirect("Admin/Index.aspx");
                        }
                        else if(tea.TIsAdmin == 0)
                        { 
                            //老师
                            Response.Redirect("Teacher/Index.aspx");
                        }
                    }
                }
                
            }
            else
            { 
                //验证码错误
                lblMsg.Text = "验证码错误";
            }
            
        }
    }
}

  testMd5.aspx   md5加密，只有后台代码，前台什么都不用写

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Security.Cryptography;
using System.Text;
namespace Web
{
    public partial class testMd5 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Response.Write(GetMd5("admin"));
        }

        private string GetMd5(string str)
        {
            //把字符串转换成字节数组
            byte[] buffer = Encoding.Default.GetBytes(str);

            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
            //md5加密
            byte[] cryptBuffer =  md5.ComputeHash(buffer);
            string s = "";
            //把每一个字节 0-255，转换成两位16进制数     
            for (int i = 0; i < cryptBuffer.Length; i++)
            {
                s += cryptBuffer[i].ToString("X2");
            }
            return s;
        }
    }
}