html>
head>
title>Ajax/title>
script type="text/javascript">
function loadXMLDoc() {
if (document.getElementById("account").value == "") {
document.getElementById("accDiv").innerHTML = "用戶名不能為空";
return;
}
var xmlHttp;
if(window.XMLHttpRequest) { // code for IE7+
xmlHttp = new XMLHttpRequest();
}
else { // code for IE5/IE6
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlHttp.onreadystatechange = function () {
if (xmlHttp.readyState == 4 xmlHttp.status == 200) {
//document.getElementById("myDiv").innerHTML=xmlHttp.responseText;
if (xmlHttp.responseText == "true") {
document.getElementById("accDiv").innerHTML = "用戶名不可用";
}
else {
document.getElementById("accDiv").innerHTML = "用戶名可用";
}
}
}
var a = document.getElementById("account").value;
// get
xmlHttp.open("GET", "validate.aspx?account=" + a + "random=" + Math.random, true);
xmlHttp.send();
}
function delData() {
document.getElementById("account").value = "";
document.getElementById("accDiv").innerHTML = "";
}
/script>
/head>
body>
h3>ajax/h3>
table>
tr>
td>賬號(hào):/td>td>input id="account" type="text" onblur="loadXMLDoc();" onfocus="delData();"/>/td>td>div id="accDiv">/div>/td>
/tr>
tr>
td>密碼:/td>td>input id="passwd" type="password" />/td>
/tr>
tr>
td>確認(rèn)密碼:/td>td>input id="vPasswd" type="password" />/td>
/tr>
tr>
td>姓名:/td>td>input id="name" type="text" />/td>
/tr>
/table>
/body>
/html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.Sql;
using System.Data.SqlClient;
public partial class Ajax_validate_validate : System.Web.UI.Page
{
public SqlConnection conn;
protected void Page_Load(object sender, EventArgs e)
{
Response.Clear();
if (Exists(Request.QueryString["account"]))
Response.Write("true");
else
Response.Write("false");
Response.End();
}
/// summary>
/// 獲取數(shù)據(jù)庫連接
/// /summary>
/// returns>/returns>
protected SqlConnection GetConnection()
{
string str = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
conn = new SqlConnection(str);
return conn;
}
protected bool Exists(string account)
{
using (GetConnection())
{
try
{
conn.Open();
string sqlStr = "select count(*) from userinfo where account='" + account + "'";
SqlCommand cmd = new SqlCommand(sqlStr, conn);
int row = Convert.ToInt32(cmd.ExecuteScalar());
if (row > 0)
return true;
else
return false;
}
catch (Exception e)
{
throw e;
}
finally
{
conn.Close();
}
}
}
}
注意:在后臺(tái)往請(qǐng)求頁面寫數(shù)據(jù)時(shí),當(dāng)寫完要發(fā)送的數(shù)據(jù)之后,需要調(diào)用Response.end()方法來終止寫入,否則可能會(huì)發(fā)送一個(gè)完整頁面過去。