在Javascirpt代碼中，調(diào)用Jquery的方法$.Ajax(function)實(shí)現(xiàn)Ajax,傳遞賬號信息給Web服務(wù)，Web服務(wù)再調(diào)用數(shù)據(jù)庫操作類查詢數(shù)據(jù)庫，并返回?cái)?shù)據(jù)給前臺(tái)頁面。

詳細(xì)代碼如下：
Default.aspx

復(fù)制代碼代碼如下:

 
<%@ 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");　　//賬號已存在 
else 
$("#<%=IsExist.ClientID%>").text("No");　　 
} 
}); 
} 
); 
}) 
</script> 
</head> 
<body> 
<form id="form1" runat="server"> 
<div> 
<table style="width:100%;"> 
<tr> 
<td> 
&nbsp;</td> 
<td> 
&nbsp;</td> 
<td> 
&nbsp;</td> 
</tr> 
<tr> 
<td> 
&nbsp;</td> 
<td> 
<asp:TextBox ID="UserID" runat="server"></asp:TextBox> 
<asp:Label ID="IsExist" runat="server" Visible="true"></asp:Label> 
</td> 
<td> 
&nbsp;</td> 
</tr> 
<tr> 
<td> 
&nbsp;</td> 
<td> 
&nbsp;</td> 
<td> 
&nbsp;</td> 
</tr> 
</table> 
</div> 
</form> 
</body> 
</html> 

WebService1.asmx.cs

復(fù)制代碼代碼如下:

 
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 的摘要說明 
/// </summary> 
[WebService(Namespace = "http://tempuri.org/")] 
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] 
[System.ComponentModel.ToolboxItem(false)] 
// 若要允許使用 ASP.NET AJAX 從腳本中調(diào)用此 Web 服務(wù)，請取消對下行的注釋。 
[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

復(fù)制代碼代碼如下:

 
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> 
/// 數(shù)據(jù)庫操作類 
/// </summary> 
public class SqlHelper 
{ 
private static SqlConnection conn; 
private static SqlCommand comm; 
private static SqlDataReader dr; 
/// <summary> 
/// 打開數(shù)據(jù)庫連接 
/// </summary> 
public static void ConnOpen() 
{ 
try 
{ 
conn = new SqlConnection(ConfigurationManager.ConnectionStrings["BBS"].ConnectionString); 
conn.Open(); 
} 
catch (Exception e) 
{ 
Console.WriteLine( e.Message); 
} 
} 
/// <summary> 
/// 關(guān)閉數(shù)據(jù)庫連接，釋放資源 
/// </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; 
} 
} 
} 
} 