验证码登录

    <script language="javascript" type="text/javascript">
function change() 
{
    document.getElementById("imgCode").src="Code.aspx?"+Math.random();

}

                            <tr>
                                <td align="center" valign="middle" class="Zitilansedenglu">
                                    验证：</td>
                                <td align="left" valign="middle" class="Zitilansedenglu">
                                    <%--   <input name="admincode" type="text" class="Denglubiaodaner" id="admincode" />--%>
                                    <input name="TxtCode" type="text" class="Denglubiaodaner" id="TxtCode" />
                                    <b id="Code">
                                        <img src="Code.aspx" id="imgCode" onclick="change()" onmouseover="this.style.cursor='hand'"
                                            height="25px" /></b>
                                </td>
                            </tr>

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.OleDb;
using webA;
using webinfo;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void BtnSubmit_Click(object sender, ImageClickEventArgs e)
    {
        if (Page.IsValid == true)
        {
            Admins admin = Login2.ValidateUser(TextBox1.Text.Trim(), TextBox2.Text.Trim());
            if (admin == null || admin.ID == 0)
            {
                Response.Write("<script type='text/javascript'>alert('您输入的用户名和密码有误，请重新输入！！');</script>");
            }
            else
            {
                Session["user"] = admin;
                Response.Redirect("Main.aspx");

            }

        }
    }
}

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

using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

using System.Data.OleDb;
using webA;
namespace webinfo {
/// <summary>
///Login 的摘要说明
/// </summary>
public static class Login2
{
    
    public static Admins ValidateUser(string adminname, string adminpassword)
    {
        string sqlCommand = "select adminname,adminpassword ,ID from web_admin where " +
            "(adminname = ?) and (adminpassword = ?)";
        
        OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.Web.HttpContext.Current.Server.MapPath("~/App_Data/www.web.com.mdb"));
        OleDbCommand command = new OleDbCommand();

            
        command.Parameters.Add(new OleDbParameter("adminname", adminname));
        command.Parameters.Add(new OleDbParameter("adminpassword", Common.GetMD5(adminpassword)));
        command.Connection = conn;
        command.CommandText = sqlCommand;

        conn.Open();

        Admins admin = null;
        using (OleDbDataReader dataReader = command.ExecuteReader())
        {
            admin = new Admins();
            if (dataReader.Read())
            {
                admin.ID = int.Parse(dataReader["ID"].ToString());
                admin.adminname = dataReader["adminname"].ToString();

            }
        }

        conn.Close();

        return admin;
    }

}
}

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;
using System.Drawing;

public partial class Code : System.Web.UI.Page
{
private void Page_Load(object sender, System.EventArgs e)
{
if (!Page.IsPostBack)
{
string strCode = this.RndNum(4);
Session["CodeValue"] = strCode;
this.CreateImage(strCode);
}

}

private void CreateImage(string checkCode)
{
int iwidth = (int)(checkCode.Length * 15);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 25);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);
////定义颜色
//Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Brown, Color.DarkCyan, Color.Purple, Color.YellowGreen };
////定义字体 
//string[] font = { "Times New Roman", "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
//定义颜色
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Brown, Color.DarkCyan, Color.Purple, Color.YellowGreen };
//定义字体 
string[] font = { "Times New Roman","Microsoft Sans Serif", "Comic Sans MS" };
Random rand = new Random();
//随机输出噪点
for (int i = 0; i < 50; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
}

//输出不同字体和颜色的验证码字符
for (int i = 0; i < checkCode.Length; i++)
{
int cindex = rand.Next(7);//从7种颜色中随机取
int findex = rand.Next(3);//从6种字体中随机取

Font f = new System.Drawing.Font(font[findex], 13, System.Drawing.FontStyle.Regular);
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), ii);
}
//画一个边框
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);

//输出到浏览器
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.ClearContent();
Response.ContentType = "image/Jpeg";
Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}

//生成随机数函数中从Vchar数组中随机抽取
//字母区分大小写
private string RndNum(int VcodeNum)
{
string Vchar = "0,1,2,3,4,5,6,7,8,9";
//Vchar = 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 VNum = "";//由于字符串很短，就不用StringBuilder了
int temp = -1;//记录上次随机数值，尽量避免生产几个一样的随机数

//采用一个简单的算法以保证生成随机数的不同
Random rand = new Random();
for (int i = 1; i < VcodeNum + 1; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
}
int t = rand.Next(10);
if (temp != -1 && temp == t)
{
return RndNum(VcodeNum);
}
temp = t;
VNum += VcArray[t];

}
return VNum;
}

 

}