1.在页面的<script type="text/JavaScript" >内加入

//无刷新请求的xmlhttp请求

var http_request=false;

function createRequest(url)

{

http_request = false;

if (window.XMLHttpRequest) { // Mozilla, Safari,...

http_request = new XMLHttpRequest();

if (http_request.overrideMimeType) {

http_request.overrideMimeType('text/html');

}

} else if (window.ActiveXObject) { // IE

try {

http_request = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {

try {

http_request = new ActiveXObject("Microsoft.XMLHTTP");

} catch (e) {}

}

}

if (!http_request) {

alert('不能创建XMLHTTP实例!');

return false;

}

http_request.onreadystatechange=alertContents;

http_request.open("POST",url,true);

http_request.send(null);

}

2.调用--在js调用请求【CONTROL为servlet配置的url-mapping,传参跟一般url传参一样】

createRequest('CONTROL'+'?cmd=listen');

3.在servlet中处理【中文乱码问题】

PrintWriter out;

response.setContentType("html/text");//此5行必备，用于输出中文，否则乱码

response.setCharacterEncoding("UTF-8");

response.setHeader("Cache-Control","no-cache");

out=response.getWriter();

out.println("对不起，系统忙，请稍后再试！"); //为返回的响应结果，在页面直接以alert()显示