Jquery+WebService 校验账号是否已被注册

在Javascirpt代码中，调用Jquery的方法$.Ajax(function)实现Ajax,传递账号信息给Web服务，
Web服务再调用数据库操作类查询数据库，并返回数据给前台页面。详细代码如下：

Default.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Ajax_XML._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></title>
<script type="text/javascript" src="jquery-1.3.2-vsdoc2.js" language="javascript"></script>
<script type="text/javascript" language="javascript">
    $(function() {
        $("#<%=UserID.ClientID%>").keyup(
                function() {
                    $.ajax({
                        type: "POST",
                        contentType: "application/json",
                        dataType: "json",
                        url: "WebService1.asmx/UserIsExist",
                        data: "{UserID:'" + $("#<%=UserID.ClientID%>").val() + "'}",
                        success: function(result) {
                            if (result.d == "true")
                                $("#<%=IsExist.ClientID%>").text("Yes");　　//账号已存在
                            else
                                $("#<%=IsExist.ClientID%>").text("No");　　
                        }

                    });
                }
                );

    })

</script>
</head>

<body>
    <form id="form1" runat="server">
    <div>

        <table style="width:100%;">
            <tr>
                <td>
                     </td>
                <td>
                     </td>
                <td>
                     </td>
            </tr>
            <tr>
                <td>
                     </td>
                <td>
                    <asp:TextBox ID="UserID" runat="server"></asp:TextBox>
                    <asp:Label ID="IsExist" runat="server" Visible="true"></asp:Label>
                </td>
                <td>
                     </td>
            </tr>
            <tr>
                <td>
                     </td>
                <td>
                     </td>
                <td>
                     </td>
            </tr>
        </table>

    </div>
    </form>
</body>
</html>

WebService1.asmx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Text;
using DAL;

namespace Ajax_XML
{
    /// <summary>
    /// WebService1 的摘要说明
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // 若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。
     [System.Web.Script.Services.ScriptService]
    public class WebService1 : System.Web.Services.WebService
    {

        [WebMethod]
        public string HelloWorld()
        {

            return "Hello,World!";
        }
        [WebMethod]
        public string UserIsExist(string UserID)
        {

            string sql = string.Format("select * from Customers where FirstName='" + UserID+"'");

            using (SqlDataReader dr = SqlHelper.ExecuteSql(sql))
            {
                if (dr.Read())
                    return "false";
                else
                    return "true";
            }



        }
    }
}

SqlHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DAL
{
    /// <summary>
    /// 数据库操作类
    /// </summary>
    public class SqlHelper
    {
        private static SqlConnection conn;
        private static  SqlCommand comm;
        private static  SqlDataReader dr;

        /// <summary>
        /// 打开数据库连接
        /// </summary>
        public static void ConnOpen()
        {


                try
                {
                    conn = new SqlConnection(ConfigurationManager.ConnectionStrings["BBS"].ConnectionString);
                    conn.Open();
                }
                catch (Exception e)
                {
                    Console.WriteLine( e.Message);
                }

        }

        /// <summary>
        /// 关闭数据库连接，释放资源
        /// </summary>
        public static void ConnClose()
        {
            if (conn != null)
            {
                conn.Close();
            }
            if (comm != null)
            {
                comm.Dispose();
            }
        }

        public static SqlDataReader ExecuteSql(string sql)
        {
            SqlHelper.ConnOpen();
            comm = new SqlCommand(sql, conn);
            try
            {
                dr = comm.ExecuteReader();
                return dr;
            }
            catch (Exception e)
            {
                throw e;
            }

        }
    }
}

Rongie Zeng

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