本文实例为大家分享了Ajax二级联动菜单的具体代码，供大家参考，具体内容如下
index.jsp
二级菜单联动演示
var req;
window.οnlοad=function()
{//页面加载时的函数
}
function Change_Select(){//当第一个下拉框的选项发生改变时调用该函数
var province = document.getElementById('province').value;
var url = "select?id="+ escape(province);
if(window.XMLHttpRequest){
req = new XMLHttpRequest();
}else if(window.ActiveXObject){
req = new ActiveXObject("Microsoft.XMLHTTP");
}
if(req){
req.open("GET",url,true);
//指定回调函数为callback
req.onreadystatechange = callback;
req.send(null);
}
}
//回调函数
function callback(){
if(req.readyState ==4){
if(req.status ==200){
parseMessage();//解析XML文档
}else{
alert("不能得到描述信息:" + req.statusText);
}
}
}
//解析返回xml的方法
function parseMessage(){
var xmlDoc = req.responseXML.documentElement;//获得返回的XML文档
var xSel = xmlDoc.getElementsByTagName('select');
//获得XML文档中的所有标记
var select_root = document.getElementById('city');
//获得网页中的第二个下拉框
select_root.options.length=0;
//每次获得新的数据的时候先把每二个下拉框架的长度清0
for(var i=0;i
var xValue = xSel[i].childNodes[0].firstChild.nodeValue;
//获得每个标记中的第一个标记的值,也就是标记的值
var xText = xSel[i].childNodes[1].firstChild.nodeValue;
//获得每个标记中的第二个标记的值,也就是标记的值
var option = new Option(xText, xValue);
//根据每组value和text标记的值创建一个option对象
try{
select_root.add(option);//将option对象添加到第二个下拉框中
}catch(e){
}
}
}
SelectServlet.java
package com;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/***
*
* @author zdw
*
*/
public class SelectServlet extends HttpServlet
{
private static final long serialVersionUID = 1L;
public SelectServlet()
{
super();
}
public void destroy()
{
super.destroy();
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
// response.setCharacterEncoding("GBK");
response.setContentType("text/xml");
response.setHeader("Cache-Control", "no-cache");
request.setCharacterEncoding("GBK");
response.setCharacterEncoding("UTF-8");
String targetId = request.getParameter("id").toString();
System.out.println(targetId);
// 获得请求中参数为id的值
String xml_start = "";
String xml_end = "";
String xml = "";
if (targetId.equalsIgnoreCase("0"))
{
xml = "0请选择";
} else if (targetId.equalsIgnoreCase("1"))
{
xml = "1昌平";
xml += "2丰台";
xml += "3海淀";
xml += "4朝阳";
} else if (targetId.equalsIgnoreCase("2"))
{
xml = "1塘沽区";
xml += "2汉沽区";
xml += "3大港区";
xml += "4东丽区";
} else
{// 如果是3,则返回下面的字符
xml = "1济南";
xml += "2青岛";
xml += "3淄博";
xml += "4枣庄";
}
String last_xml = xml_start + xml + xml_end;
response.getWriter().write(last_xml);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doGet(request, response);
}
public void init() throws ServletException
{
}
}
web.xml
xmlns:xsi="/2001/XMLSchema-instance"
xsi:schemaLocation="/xml/ns/j2ee
/xml/ns/j2ee/web-app_2_4.xsd">
SelectServlet
com.SelectServlet
SelectServlet
/select
index.jsp
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
