一个登陆页面，包含了初始化用户，输入检测，错误处理等

一个登陆页面，包含了初始化用户，输入检测，错误处理等

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_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>无标题页</title>
    <style type="text/css">

</style>
</head>
<body>
    <form id="form1" runat="server">
    <div id="Validators">
    <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="密码不能为空！" ControlToValidate="boxPassword"></asp:RequiredFieldValidator>
    <asp:Label ID="Alert" runat="server" Text="警告：" Visible="False"></asp:Label>
    </div>

    <div id="alignbk">
         <div id="loginbk">
            <div id="login" >
               <table style=" 550px">
                   <tr>
                       <td style=" 16px">
                           <img src="images/AdminUser.gif" /></td>
                       <td style=" 205px">
                           帐号：<asp:TextBox ID="boxUserName" runat="server" CssClass="boxInput"></asp:TextBox></td>
                       <td style=" 12px">
                           <img src="images/AdminPWD.gif" /></td>
                       <td style=" 208px">
                           密码：<asp:TextBox ID="boxPassword" runat="server" CssClass="boxInput" TextMode="Password"></asp:TextBox></td>
                       <td style=" 100px">
                           <asp:ImageButton ID="btnLogin" runat="server" ImageUrl="~/images/AdminLogin.gif" OnClick="btnLogin_Click" /></td>
                   </tr>
               </table>
            </div>
            <div id="copyright">
                主办：       Copyright © 2006 <a href="http://single.dlut.edu.cn">
                    Single</a> All Rights
                Reserved.</div>

       </div>

    </div>
    </form>
</body>
</html>
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.Data.SqlClient;
using System.Text.RegularExpressions;
using System.Collections;

public partial class _Default : System.Web.UI.Page
{
    protected string strConn = ConfigurationSettings.AppSettings["strConnection"];

    protected int numErr = 5; //初始化允许登陆出错的最大次数

    protected void Page_Load(object sender, EventArgs e)
    {
        //初始化帐号密码
        //*
        // InitializtionPWD();
        //*

        if (Session["numErr"] == null )   //初始化错误次数记录数。
        {
            Session["numErr"] = 0;
        }

        if (int.Parse(Session["numErr"].ToString()) >= numErr)
        {
            btnLogin.Enabled = false;
        }

    }

    protected void btnLogin_Click(object sender, ImageClickEventArgs e)
    {

        if (int.Parse(Session["numErr"].ToString()) < 5)
        {

            string adminName = boxUserName.Text;


            //替换特殊字符',增添记录
            if (!CheckParams(adminName))
            {
                adminName = adminName.Replace("\'","\'\'");
               // adminName = adminName.Replace("=","\"=\"");
                string Insert = "Insert INTO OA_BadIP(BadIP,BadString,CreatedTime) values('" + Request.UserHostAddress + "','危险用户名[" + adminName + "]尝试登陆!','" + DateTime.Now + "')";

                SqlConnection myConn2 = new SqlConnection(strConn);
                SqlCommand myCommand2 = new SqlCommand(Insert, myConn2);
                myConn2.Open();
                myCommand2.ExecuteNonQuery();

                myCommand2.Dispose();
                myConn2.Close();

                GoError("请不要尝试破坏此系统！\\n你的计算机" + Request.UserHostAddress + "已经被记录！");
            }

            //建立数据库联接，验证用户！
            string password = FormsAuthentication.HashPasswordForStoringInConfigFile(boxPassword.Text, "SHA1");

            string mySql = "Select AdminPWD,AdminGroup,ColleageID From OA_Admin Where AdminName='" + adminName + "'";

            SqlConnection myConn = new SqlConnection(strConn);
            SqlCommand myCommand = new SqlCommand(mySql, myConn);
            myConn.Open();
            SqlDataReader myReader;
            myReader = myCommand.ExecuteReader();
            if (myReader.Read())
            {
                if (password == myReader["AdminPWD"].ToString())
                {
                    Session["AdminName"] = boxUserName.Text;
                    Session["AdminGroup"] = myReader["AdminGroup"].ToString();
                    Session["ColleageID"] = myReader["ColleageID"].ToString();
                    myReader.Close();
                    myConn.Close();
                    Response.Redirect("mail.aspx");

                }
                else
                {

                    Session["numErr"] = int.Parse(Session["numErr"].ToString()) + 1;
                    Alert.Visible = true;
                    Alert.Text = "密码错误！你还有" + (numErr - int.Parse(Session["numErr"].ToString())+1) + "次重试机会！";
                    myReader.Close();
                    myConn.Close();
                }
            }
            else
            {
                Session["numErr"] = int.Parse(Session["numErr"].ToString()) + 1;
                Alert.Visible = true;
                Alert.Text = "用户名不存在！你还有" + (numErr - int.Parse(Session["numErr"].ToString())+1) + "次重试机会！";

                myReader.Close();
                myConn.Close();
            }

        }
        else
        {
            Alert.Visible = true;
            Alert.Text = "错误记录达到最高上限，您在20分钟内无法登陆！";
            //btnLogin.Enabled = false;
        }

    }

    //=====================================
    //下面的这段程序是初始化总管理员密码。
    //======================================
    private void InitializtionPWD()
    {
        //下面的这段程序是初始化管理员信息
        //帐号:admin
        //密码:admin

        SqlConnection myConn = new SqlConnection(strConn);
        myConn.Open();
        string hashed = FormsAuthentication.HashPasswordForStoringInConfigFile("admin", "SHA1");
        string strInsert = "INSERT INTO OA_Admin(AdminName,AdminPWD,CreatedTime) Values('admin','" + hashed + "','" + DateTime.Now + "')";
        SqlCommand insert = new SqlCommand(strInsert, myConn);
        insert.ExecuteNonQuery();
        insert.Dispose();
        myConn.Close();

    }

    //==============
    // 错误提示！
    //==============
    private void GoError(string strError)
    {
        Response.Write("<script language=javascript>alert('" + strError + "\\n\\n系统将自动返回前一页面');history.back();</script>");

    }

    //===============================
    //过滤指定的字符，防止Sql注入。
    //=================================

    bool CheckParams(params object[] args)
    {
        string[] Lawlesses ={ "=", "'" };
        if (Lawlesses == null || Lawlesses.Length <= 0) return true;
        //构造正则表达式,例:Lawlesses是=号和'号,则正则表达式为 .*[=}'].*  (正则表达式相关内容请见MSDN)
        //另外,由于我是想做通用而且容易修改的函数,所以多了一步由字符数组到正则表达式,实际使用中,直接写正则表达式亦可;
        string str_Regex = ".*[";
        for (int i = 0; i < Lawlesses.Length - 1; i++)
            str_Regex += Lawlesses[i] + "|";
        str_Regex += Lawlesses[Lawlesses.Length - 1] + "].*";
        //
        foreach (object arg in args)
        {
            if (arg is string)//如果是字符串,直接检查
            {
                if (Regex.Matches(arg.ToString(), str_Regex).Count > 0)
                    return false;
            }
            else if (arg is ICollection)//如果是一个集合,则检查集合内元素是否字符串,是字符串,就进行检查
            {
                foreach (object obj in (ICollection)arg)
                {
                    if (obj is string)
                    {
                        if (Regex.Matches(obj.ToString(), str_Regex).Count > 0)
                            return false;
                    }
                }
            }
        }
        return true;
    }
}
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原文地址：https://www.cnblogs.com/kokoliu/p/523622.html