手工方式实现二级联动的效果：
- jsp页面：
<%@ page language="java" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>级联菜单</title>
<script type="text/javascript" src="xmlfile.js"> </script>
</head>
<body>
<select id="province" name="province">
<option value="">请选择....</option>
</select>
<select id="city" name="city">
<option value="">请选择.....</option>
</select>
</body>
</html>
window.onload=function(){
//1.获取对象
var xhr=ajaxFunction();
//2.监听
xhr.onreadystatechange=function(){
if(xhr.readyState==4){
if(xhr.status==200){
var docXml=xhr.responseXML;
//解析docXml的内容
var provinceXmlElements=docXml.getElementsByTagName("province");
//遍历所有的province
for(var i=0;i<provinceXmlElements.length;i++){
var provinceXmlElement=provinceXmlElements[i];
var provinceXmlValue=provinceXmlElement.getAttribute("name");
//<option value="">请选择....</option>
var option=document.createElement("option");
option.setAttribute("value",provinceXmlValue);
var text=document.createTextNode(provinceXmlValue);
option.appendChild(text);//挂接节点
var provinceDocElement=document.getElementById("province");
provinceDocElement.appendChild(option);
}
//当点击一个一个省份时触发一个事件
document.getElementById("province").onchange=function(){
//清空城市列表
var cityDocElement = document.getElementById("city");
var options = cityDocElement.getElementsByTagName("option");
for(var z=options.length-1;z>0;z--){
cityElement.removeChild(options[z]);
}
//1.页面中选中的是哪个省份
var privinceDocValue=this.value;
//2.解析xml内容中所有province的信息
for(var i=0;i<provinceXmlElements.length;i++){
var provinceXmlElement=provinceXmlElements[i];
var provinceXmlValue=provinceXmlElement.getAttribute("name");
if(privinceDocValue==provinceXmlValue){
//解析其中的city
var cityXmlElements=provinceXmlElement.getElementsByTagName("city");
//遍历city
for(var j=0;j<cityXmlElements.length;j++){
var cityXmlElement=cityXmlElements[j];
var cityXmlElementValue=cityXmlElement.firstChild.nodeValue;
//<option><option/>
var option= document.createElement("option");
option.setAttribute("value",cityXmlElementValue);
//创建一个文本节点
var text=document.createTextNode(cityXmlElementValue);
option.appendChild(text);
cityDocElement.appendChild(option);
}
}
}
//3.遍历所有的province的信息
}
}
}
}
//3.建立客户机和服务器的链接
xhr.open("get","../servlet/XmlFileServlet",true);
//4.发送数据
xhr.send(null);
}
function ajaxFunction(){
var xmlHttp;
try{ // Firefox,Opera 8.0+,Safari
xmlHttp=new XMLHttpRequest();
}
catch (e){
try{// Internet Explorer
xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e){
try{
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e){}
}
}
return xmlHttp;
}
- servlet打印xml数据
如果服务器端向客户端发送的数据格式是XML格式的话,一定设置响应首部信息:”Content-Type”为”text/xml”
package app.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class XmlFileServlet extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {
***response.setContentType("text/xml;charset=utf-8");***
PrintWriter out = response.getWriter();
/* * * 如果实际开发的话,查询数据库 * * 结果集为JavaBean类型 * * 结果集为集合内容:Array、List、Map及Set等集合 * * * 现在不查询数据库,模拟查询数据库:手工方式构建XML格式 */
//手工方式构建的XML格式,实际上就是String类型的字符串
out.println("<china>");
out.println("<province name='吉林省'>");
out.println("<city>长春</city>");
out.println("<city>吉林市</city>");
out.println("<city>四平</city>");
out.println("<city>松原</city>");
out.println("<city>通化</city>");
out.println("</province>");
out.println("<province name='辽宁省'>");
out.println("<city>沈阳</city>");
out.println("<city>大连</city>");
out.println("<city>鞍山</city>");
out.println("<city>抚顺</city>");
out.println("<city>铁岭</city>");
out.println("</province>");
out.println("<province name='山东省'>");
out.println("<city>济南</city>");
out.println("<city>青岛</city>");
out.println("<city>威海</city>");
out.println("<city>烟台</city>");
out.println("<city>潍坊</city>");
out.println("</province>");
out.println("</china>");
}
public void doPost(HttpServletRequest request,IOException {
doGet(request,response);
}
}
4.效果：
