菜单级联简单例子
<%@ page contentType="text/html; charset=GBK"%><html><head><title>下拉列表联动</title></head><body bgcolor="#ffffff"><table><tr><td><select name="s1" onChange="haha()"><option value="null">请选择<option value="1">1<option value="2">2<option value="3">3<option value="4">4</select></td><td id="heihei"><select><option>请先选择第一个下拉</select></td></tr></table><script>//定义XMLHttpRequest对象var http_request = false;function send_request(url) {http_request = false;//开始初始化XMLHttpRequest对象if (window.XMLHttpRequest) {//Mozilla等浏览器初始化XMLHttpRequest过程http_request = new XMLHttpRequest();//有些版本的Mozilla浏览器处理服务器返回的未包含XML mime-type头部信息的内容时会出错.//因此,要确保返回的内容包含text/xml信息.if (http_request.overrideMimeType) {http_request.overrideMimeType("text/xml");}} else if (window.ActiveXObject) {//IE浏览器初始化XMLHttpRequest过程try {http_request = new ActiveXObject("Msxml2.XMLHTTP");} catch (e) {try {http_request = new ActiveXObject("Microsoft.XMLHTTP");} catch (e) {}}}//异常,创建对象失败if (!http_request) {window.alert("不能创建XMLHttpRequest对象实例!");return false;}//指定响应处理函数http_request.onreadystatechange = processRequest;//发送HTTP请求信息http_request.open("GET", url, true);http_request.send(null);}//处理返回信息函数function processRequest() {//判断对象状态if (http_request.readyState == 4) {//判断HTTP状态码if (http_request.status == 200) {//信息已经成功返回//window.document.write(http_request.responseText);//alert(http_request.responseText);document.getElementById("heihei").innerHTML = http_request.responseText;} else {//请求页面有问题alert("您所请求的页面有异常!错误状态:" + http_request.status);}}}function haha() {var flag = document.all("s1").value;send_request("b.jsp?flag=" + flag);}</script></body></html>?
<%@ page contentType="text/html; charset=GB2312"%><% String flag=request.getParameter("flag"); if("1".equals(flag)){%><select name="s2"><option value="a">a<option value="b">b<option value="c">c<option value="d">d</select><% }else if("2".equals(flag)){%><select name="s2"><option value="e">e<option value="f">f<option value="g">g<option value="h">h</select><% }else{%><select name="s2"><option value="null">此项没有内容</select><% }%>?