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：
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");
}
});
}
);
</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>
<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 UserIsExist(string UserID)
{
string sql = string.Format("select * from Customers where FirstName='" + UserID+"'");
{
if (dr.Read())
return "false";
else
return "true";
}
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]
{
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";
}
}
}
}