用AJAX编写用户注册实例——我所举的这个例子是一个企业用户注册时的一个应用，当用户注册时检查用户名和企业名是否可用，以前的做法是在旁边加一个按钮，点击“检查”，就向服务器发出请求，然后等待……服务器返回信息，继续操作。
<%@page language="java" contentType="text/html;charset=GBK"%>
<script language="javascript" type="text/javascript">
<!--
/**//**Ajax 开始 by Alpha 2005-12-31*/
var http = getHTTPObject();
function handleHttpResponse(){
if(http.readyState == 4){
if(http.status == 200){
var
xmlDocument = http.responseXML;
if(http.responseText!=""){
document.getElementById("showStr").style.display = "";
document.getElementById("userName").style.background= "#FF0000";
document.getElementById("showStr").innerText = http.responseText;
}else{
document.getElementById("userName").style.background= "#FFFFFF";
document.getElementById("showStr").style.display = "none";
}
}
else{
alert("你所请求的页面发生异常，可能会影响你浏览该页的信息！");
alert(http.status);
}
}
}
function handleHttpResponse1(){
if(http.readyState == 4){
if(http.status == 200){
var
xmlDocument = http.responseXML;
if(http.responseText!=""){
document.getElementById("comNmStr").style.display = "";
document.getElementById("comNm").style.background= "#FF0000";
document.getElementById("comNmStr").innerText = http.responseText;
}else{
document.getElementById("comNm").style.background= "#FFFFFF";
document.getElementById("comNmStr").style.display = "none";
}
}
else{
alert("你所请求的页面发生异常，可能会影响你浏览该页的信息！");
alert(http.status);
}
}
}
function chkUser(){
var url = "/chkUserAndCom";
var name = document.getElementById("userName").value;
url += ("&userName="+name+"&oprate=chkUser");
http.open("GET",url,true);
http.onreadystatechange = handleHttpResponse;
http.send(null);
return ;
}
function chkComNm(){
var url = "/chkUserAndCom";
var name = document.getElementById("comNm").value;
url += ("&comName="+name+"&oprate=chkCom");
http.open("GET",url,true);
http.onreadystatechange = handleHttpResponse1;
http.send(null);
return ;
}
//该函数可以创建我们需要的XMLHttpRequest对象
function getHTTPObject(){
var
xmlhttp = false;
if(window.XMLHttpRequest){
xmlhttp = new XMLHttpRequest();
if(
xmlhttp.overrideMimeType){
xmlhttp.overrideMimeType('text/
xml');
}
}
else{
try{
xmlhttp = new ActiveXObject("Ms
xml2.XMLHTTP");
}catch(e){
try{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}catch(E){
xmlhttp = false;
}
}
}
return
xmlhttp;
}
/**//**Ajax 结束*/
//检测表单
function chkpassword()
{
var m=document.form1;
if(len(m.password.value) > 20 || len(m.password.value) < 5 || !isStr(m.password.value))
{
document.getElementById("passwordStr").style.display = "";
document.getElementById("password").style.background= "#FF0000";
document.getElementById("passwordStr").innerText = "对不起,密码必须为英文字母、数字或下划线，长度为5~20!";
}
else
{
document.getElementById("password").style.background= "#FFFFFF";
document.getElementById("passwordStr").style.display = "none";
}
}
function chkconfirmPassword()
{
var m=document.form1;
if (m.password.value != m.confirmPassword.value)
{
document.getElementById("confirmPasswordStr").style.display = "";
document.getElementById("confirmPassword").style.background= "#FF0000";
document.getElementById("confirmPasswordStr").innerText = "对不起,密码与重复密码不一致!";
}
else
{
document.getElementById("confirmPassword").style.background= "#FFFFFF";
document.getElementById("confirmPasswordStr").style.display = "none";
}
}
function checkfield()
{
var m=document.form1;
if(m.userName.value.length==0)
{
alert("对不起,用户名必须为英文字母、数字或下划线，长度为5~20。");
m.userName.focus();
return false;
}
if(m.password.value.length==0)
{
alert("对不起,密码必须为英文字母、数字或下划线，长度为5~20。");
m.password.focus();
return false;
}
if (m.password.value != m.confirmPassword.value)
{
alert("对不起,密码与重复密码不一致!");
m.confirmPassword.focus();
return false;
}
if(m.comNm.value.length==0)
{
alert("对不起,企业名称不能为空！！");
m.comNm.focus();
return false;
}
m.submit();
}
//-->
</script>
<body topmargin="0">
<form name="form1" method="post" action="/Control?act=Register">
<table width="100%">
<tr><td align="center"> <H2>Ajax 演示程序</H1></td></tr>
<tr><td align="center"> ------ 企业注册 By Alpha</td></tr>
</table>
<HR>
<table width="400" border="0" cellpadding="1" cellspacing="1" align="center" >
<tr>
<td><font color="red">*</font></td>
<td>用户帐号:</td>
<td>
<input type="text" name="userName" maxlength="20" style="background:#FFFFFF" onBlur="chkUser()" value=""/>
<div id="showStr" style="background-color:#FF9900;display:none"></div>
</td>
</tr>
<tr>
<td><font color="red">*</font></td>
<td>企业名称:</td>
<td>
<input type="text" name="comNm" maxlength="100" style="background:#FFFFFF" onBlur="chkComNm()" value=""/>
<div id="comNmStr" style="background-color:#FF9900;display:none"></div>
</td>
</tr>
<tr>
<td><font color="red">*</font></td>
<td>用户密码:</td>
<td><input type="password" name="password" maxlength="20" style="background:#FFFFFF" onBlur="chkpassword()"/>
<div id="passwordStr" style="background-color:#FF9900;display:none"></div>
</td>
</tr>
<tr>
<td><font color="red">*</font></td>
<td>确认密码:</td>
<td><input type="password" name="confirmPassword" maxlength="20" style="background:#FFFFFF" onBlur="chkconfirmPassword()"/>
<div id="confirmPasswordStr" style="background-color:#FF9900;display:none"></div>
</td>
</tr>
</table>
<div align="center">
<input type="button" name="ok" value=" 确 定 " onclick="checkfield()">
<input type="reset" name="reset" value=" 取 消 ">
</div>
</form>
</body>
</html>
