主页面（要求刷新的页面）要求每一分钟刷新一次系统时间
<html>
<body onload=makeRequest(getSystemTime.jsp)> //创建httpRequest对象
<form name=dateForm>
<table>
<td colspan=2 align=center>
<div id=sysTimeShow></div> //显示平台系统时间
</td>
</table></form>
</body>
</html>
getSystemTime.jsp //获得系统的当前时间，也就是输出结果的页面
<%@ page language=java %>
<%@ page contentType=text/html;charset=GB2312 %>
<%@ page import=java.util.Date%>
<%@ page import=java.sql.Timestamp%>
<%@ page import=java.io.IOException%>
<%
Date d = new Date();
Timestamp ts = new Timestamp(d.getTime());
String result = ts.toString().substring(0,16);
out.write(result,0,result.length());
%>
ajax.js
function makeRequest(url) {
http_request = false;
if (window.XMLHttpRequest) {
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType){
http_request.overrideMimeType(text/xml);
}
} else if (window.ActiveXObject) {
try{
http_request = new ActiveXObject(Msxml2.XMLHTTP);
} catch (e) {
try {
http_request = new ActiveXObject(Microsoft.XMLHTTP);
} catch (e) {
}
}
}
if (!http_request) {
alert(您的浏览器不支持当前操作，请使用 IE 5.0 以上版本!);
return false;
}
//定义页面调用的方法init,不是init();没有();
http_request.onreadystatechange = init;
http_request.open(GET, url, true);
//禁止IE缓存
http_request.setRequestHeader(If-Modified-Since,0);
//发送数据
http_request.send(null);
//每60秒刷新一次页面
setTimeout(makeRequest(+url+), 60000);
}
function init() {
if (http_request.readyState == 4) {
if (http_request.status == 0 || http_request.status == 200) {
var result = http_request.responseText;
if(result==){
result = 系统时间获取失败;
}
document.getElementById (sysTimeShow).innerHTML=平台系统时间：+result;
} else {//http_request.status != 200
alert(请求失败!);
}
}
}
