<script type="text/javascript"> var http_request = false; function createXMLHttpRequest() { if (window.ActiveXObject) { // IE浏览器 http_request = new ActiveXObject("Msxml2.XMLHTTP"); //创建XMLHttpRequest对象 }else if (window.XMLHttpRequest) { // 非IE浏览器 http_request = new XMLHttpRequest(); //创建XMLHttpRequest对象 } if (!http_request) { alert("不能创建XMLHttpRequest对象实例！"); return false; } } function getResult() { var responseContext; //用于存放从服务器返回的响应结果 if (http_request.readyState == 4) { // 判断请求状态 if (http_request.status == 200) { // 请求成功，开始处理返回结果 responseContext = http_request.responseText; //获取服务器的响应内容 if(responseContext.indexOf("true")!=-1){ alert("恭喜您！该用户名有效！"); }else{ alert("抱歉！该用户名已经被注册！"); } } else { // 请求页面有错误 alert("您所请求的页面有错误！"); } } }
function checkUsername(username) { if (username.value == "") { alert("请输入用户名！"); username.focus(); return; } else { createXMLHttpRequest(); http_request.onreadystatechange = getResult; //调用返回结果处理函数 http_request.open("GET","CheckUser?username="+username.value, true); //创建与服务器的连接 http_request.send(null); //向服务器发送请求 } }</script>
例子2：
<script type="text/javascript">
var xmlHttp = false;
function createXMLHttpRequest(){
if(window.ActiveXObject){
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP.3.0");
}else if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
}
function startRequest(){
createXMLHttpRequest();
xmlHttp.onreadystatechange = handleStateChange;
xmlHttp.open("GET", "http://localhost:8080/MyFirstWebPro/user.xml", false);
xmlHttp.send();
}
function handleStateChange(){
if(xmlHttp.readyState == 4){
if(xmlHttp.status == 200){
document.getElementById("results").innerHTML = xmlHttp.responseText;
}else{
alert("您所请求的页面有错误！");
}
}
}
</script>
<body >
<div id="results"></div>
user.xml如下
<?xml version="1.0" encoding="gb2312"?>
<table>
<tr>
<th>姓名</th>
<th>年龄</th>
<th>性别</th>
</tr>
<tr>
<td>王丽丽</td>
<td>22</td>
<td>女</td>
</tr>
<tr>
<td>张芳</td>
<td>22</td>
<td>女</td>
</tr>
<tr>
<td>张辉</td>
<td>22</td>
<td>男</td>
</tr>
</table>
时间： 2024-11-11 04:23:27