C#用AJAX验证用户登陆 使用三层结构

DAL:

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Xml;
using System.Xml.Xsl;
using System.Xml.XPath;
namespace DAL
{
    public static class DBHelper
    {
        
        /**//// <summary>
        /// 创建DbCommand的方法
        /// </summary>
        /// <returns></returns>
        public static DbCommand CreateCommand()
        {
            string connectionString = ConfigurationManager.AppSettings["connString"];
            string providerName = ConfigurationManager.AppSettings["provName"];
            DbProviderFactory factory = DbProviderFactories.GetFactory(providerName);
            DbConnection conn = factory.CreateConnection();
            conn.ConnectionString = connectionString;
            DbCommand cmd = conn.CreateCommand();
            return cmd;
        }
        /**//// <summary>
        /// 返回DataTabale的方法，第一重重载
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable ExecuteCommand(string sql)
        {
            DataTable table = new DataTable();
            DbDataReader reader = null;
            DbCommand cmd = DBHelper.CreateCommand();
            cmd.CommandText = sql;
            try
            {
                
                cmd.Connection.Open();
                reader = cmd.ExecuteReader();
                table.Load(reader);
            }
            catch (Exception ex)
            {

                throw ex;
            }
            finally
            {
                reader.Close();
                cmd.Connection.Close();
            }
            return table;
        }
        /**//// <summary>
        /// 返回DataTabale的方法，第二重重载，可执行存储过程
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="values"></param>
        /// <returns></returns>
        public static DataTable ExecuteCommand(string sql, params DbParameter[] values)
        {
            DataTable table = new DataTable();
            DbDataReader reader = null;
            DbCommand cmd = DBHelper.CreateCommand();
            cmd.CommandText = sql;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddRange(values);
            try
            {
                cmd.Connection.Open();

                reader = cmd.ExecuteReader();
                table.Load(reader);

            }
            catch (Exception ex)
            {

                throw ex;
            }
            finally
            {
                reader.Close();
                cmd.Connection.Close();
            }
            return table;
        }
        /**//// <summary>
        /// 执行修改、删除、添加数据库中表的方法，第一重重载
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static int ExecuteNoQuery(string sql)
        {
            int affect = -1;
            DbCommand cmd = DBHelper.CreateCommand();
            cmd.CommandText = sql;
            try
            {
                cmd.Connection.Open();
                affect = cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                cmd.Connection.Close();
            }
            return affect;

        }
        /**//// <summary>
        /// 执行修改、删除、添加数据库中表的方法，第二重重载，可执行存储过程
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="values"></param>
        /// <returns></returns>
        public static int ExecuteNoQuery(string sql,params DbParameter[] values)
        {
            int affect = -1;
            DbCommand cmd = DBHelper.CreateCommand();
            cmd.CommandText = sql;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddRange(values);
            try
            {
                cmd.Connection.Open();
                affect = cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                cmd.Connection.Close();
            }
            return affect;

        }
        /**//// <summary>
        /// 返回数据表的第一行第一列，第一重重载
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static string GetScalar(string sql)
        {
            string result = null;
            DbCommand cmd = DBHelper.CreateCommand();
            cmd.CommandText = sql;
            try
            {
                cmd.Connection.Open();
                result = cmd.ExecuteScalar().ToString();
            }
            catch(Exception ex)
            {

                result = (string)(cmd.ExecuteScalar());
            }
            finally
            {
                cmd.Connection.Close();
            }
            return result;
        }
        /**//// <summary>
        /// 返回数据表的第一行第一列，第二重重载，可执行存储过程
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="values"></param>
        /// <returns></returns>
        public static string GetScalar(string sql, params DbParameter[] values)
        {
            string result = null;
            DbCommand cmd = null;
            cmd.CommandText = sql;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddRange(values);
            try
            {
                cmd = DBHelper.CreateCommand();
                cmd.Connection.Open();
                result = cmd.ExecuteScalar().ToString();
            }
            catch (Exception ex)
            {
                result = (string)(cmd.ExecuteScalar());
            }
            finally
            {
                cmd.Connection.Close();
            }
            return result;
        }
        /**//// <summary>
        /// 把数据转换成XML形式输出，第一重重载
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static string GetXmlReaderString(string sql)
        {
            StringBuilder xmlString = new StringBuilder();
            SqlCommand sqlcmd = (SqlCommand)(DBHelper.CreateCommand());
            sqlcmd.CommandText = sql;
            try
            {
                sqlcmd.Connection.Open();
                XmlReader reader = sqlcmd.ExecuteXmlReader();
                reader.Read();
                xmlString.Append("<root>");
                while (!reader.EOF)
                {
                    xmlString.Append(reader.ReadOuterXml());
                }
                xmlString.Append("</root>");
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                sqlcmd.Connection.Close();
            }
            return xmlString.ToString();
        }
        /**//// <summary>
        /// 把数据转换成XML形式输出，第二重重载，可执行存储过程
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="values"></param>
        /// <returns></returns>
        public static string GetXmlReaderString(string sql,params SqlParameter[] values)
        {
            StringBuilder xmlString = new StringBuilder();
            SqlCommand sqlcmd = (SqlCommand)(DBHelper.CreateCommand());
            sqlcmd.CommandText = sql;
            sqlcmd.CommandType = CommandType.StoredProcedure;
            sqlcmd.Parameters.AddRange(values);    
            try
            {
                sqlcmd.Connection.Open();
                XmlReader reader = sqlcmd.ExecuteXmlReader();
                reader.Read();
                xmlString.Append("<root>");
                while (!reader.EOF)
                {
                    xmlString.Append(reader.ReadOuterXml());
                }
                xmlString.Append("</root>");
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                sqlcmd.Connection.Close();
            }
            return xmlString.ToString();
        }

    }
}

Model:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Model
{
    public class User
    {
        string username;
        string password;
        public string Username
        {
            get { return this.username; }
            set { this.username = value; }
        }
        public string Password
        {
            get { return this.password; }
            set { this.password = value; }

        }
    }
}

BLL:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Model;
using DAL;
using System.Data;
namespace BLL
{
    public class BLLCheckUser
    {
        public static string Check(User user)
        {
            string sql = "select * from tb_User where UserId='" + user.Username + "' and Password='" + user.Password + "'";
            DataTable table = DBHelper.ExecuteCommand(sql);
            if (table.Rows.Count > 0)
            {
                if(table.Rows[0]["UserId"].ToString()!="")
                return "true";
            }
            return "false";
        }
    }
}

页面：

<%@ 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></title>
<style type="text/css">
body{}{
    text-align: center;
    font-size: 12px;
    color:#666;
    font-family: font-family: Arial, Helvetica, sans-serif;
}
table
{}{
    margin-top: 160px;
    padding-top: 30px;
    padding-bottom: 30px;
    border: solid 2px #333;
    background: #fafcfd;
    
}
h1
{}{
    width: 200px;
    font-size:24px;
    text-align: center;
    margin: 0;
    padding: 0;
    margin-left: 100px;
    
}
td{}{
    width: 200px;
    height: 30px;
    padding: 6px;
}
.field
{}{
    width: 120px;
    border: solid 1px #ccc;

}
.login_btn
{}{
    border: solid 1px #ccc;
    background: #fafcfd;
    text-align:center;
    width: 60px;
    font-size: 12px;
    color: #666;
    margin: 10px;
    padding-top:2px;
    line-height: 16px;
}
    </style>
</head>
<body>
    <form action="Office.aspx" method="post">
        <table align="center">
            <tr>
                <td colspan="2"><h1>Office办公自动化</h1></td>
            </tr>
            <tr>
                <td align="right">用户名：</td>
                <td align="left"><input type="text" size="9" class="field" id="_name"/></td>
            </tr>
            <tr>
                <td align="right">密 &nbsp;码：</td>
                <td align="left"><input type="password" class="field" id="_pwd"/></td>
            </tr>
            <tr>
                <td align="right"><input type="button" value="登陆" class="login_btn" onclick="sendTo()"/><input type="submit" id="submit" style="display:none"/></td>
                <td align="left"><input type="reset"value="取消" class="login_btn"/></td>
            </tr>         
        </table>
    </form>
</body>
</html>

JS脚本：

function InitHttpRequest()
{
    var HttpRequest=null;
    if(window.ActiveXObject)
    {
        try{
        HttpRequest=new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch(e)
        {
            try{
                HttpRequest=new ActiveXObject("Microsofr.XMLHTTP");
            }
            catch(e)
            {
            }
        }
    }
    else if(window.XMLHttpRequest)
    {
        HttpRequest = new XMLHttpRequest();
    }
    return HttpRequest;
}
function sendRequest(url,data)
{
    var Request = InitHttpRequest();
    Request.onreadystatechange = function() {
        if (Request.readyState == 4 && Request.Status == 200) {
            var recieve = Request.responseText;
            if (recieve == "true") {
                document.getElementById("submit").click();
                //alert("验证通过！");
            }
            else {
                alert("用户名或密码错误！");
            }
        }
    }
    Request.open("POST", url, false);
    Request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    Request.send(data);
}
function sendTo()
{
    var url = "Ajax/CheckUser.aspx";
    var post_str = "_name=" + document.getElementById("_name").value + "&_pwd=" + document.getElementById("_pwd").value;//构造POST参数
    sendRequest(url,post_str);
}

异步调用页面：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Model;
using BLL;
public partial class AJAX_CheckUser : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string username = Request.Params["_name"];
        string password = Request.Params["_pwd"];
        User user = new User();
        user.Username = username;
        user.Password = password;
        string check = BLLCheckUser.Check(user);
        Response.Write(check);
    }
}