js使用xml数据载体实现城市省份二级联动效果

更新时间：2020-06-14 19:54:01 作者：startmvc

本文实例为大家分享了使用xml数据载体实现城市省份二级联动的具体代码，供大家参考，具

本文实例为大家分享了使用xml数据载体实现城市省份二级联动的具体代码，供大家参考，具体内容如下

首先写好前台页面testProvince.jsp，将请求通过open、send发送到服务器


<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
 <head> 
 <base href="<%=basePath%>" rel="external nofollow" > 
 <title>二级联动</title> 
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0"> 
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <style type="text/css"> 
 select{ 
 width:111px; 
 } 
 </style> 
 </head> 
 
 <body> 
 <select id="provinceID"> 
 <option>选择省份</option> 
 <option>湖南</option> 
 <option>广东</option> 
 </select> 
 
 <select id="cityID"> 
 <option>选择城市</option> 
 </select> 
 </body> 
 <script type="text/javascript"> 
 //创建ajax对象 
 function createAjax(){ 
 var ajax = null; 
 try{ 
 ajax = new ActiveXObject("microsoft.xmlhttp"); 
 }catch(e){ 
 try{ 
 ajax = new XMLHttpRequest(); 
 }catch(e1){ 
 alert("请更换浏览器"); 
 } 
 } 
 return ajax; 
 } 
 </script> 
 
 <script type="text/javascript"> 
 document.getElementById("provinceID").onchange = function(){ 
 //清空城市除了第一项 
 var cityElem = document.getElementById("cityID"); 
 cityElem.options.length = 1; 
 
 //获取选中的省份 
 var province = this.value; 
 //进行编码处理 
 province = encodeURI(province); 
 if("选择省份" != province){ 
 var ajax = createAjax(); 
 //提交方式为GET 
 var method = "GET"; 
 //提交路径为servlet路径 
 var url = "${pageContext.request.contextPath}/ProvinceServlet?time=" + new Date().getTime()+ 
 "&province=" +province; 
 //准备发送异步请求 
 ajax.open(method, url); 
 //由于是get请求，所以不需要设置请求头 
 //发送请求 
 ajax.send(null); 
 
 //监听服务器响应状态的变化 
 ajax.onreadystatechange = function(){ 
 //响应状态为4 表示ajax已经完全接受到服务器的数据了 
 if(ajax.readyState == 4){ 
 //接收到的数据正常 
 if(ajax.status == 200){ 
 //获取服务器传来的html数据 
 var xmlDocument = ajax.responseXML; 
 //进行dom操作解析xml 
 //解析xml数据 
 var citys = xmlDocument.getElementsByTagName("city"); 
 for(var i = 0; i< citys.length;i++){ 
 //获取xml中的值 :不能用innerHTML,要用nodeValue 
 var city = citys[i].firstChild.nodeValue; 
 //创建option 
 var optElement = document.createElement("option"); 
 optElement.innerHTML = city; 
 //获取city 
 var cityElems = document.getElementById("cityID"); 
 cityElems.appendChild(optElement); 
 } 
 
 } 
 } 
 } 
 } 
 
 } 
 
 
 </script> 
</html>

然后在后台ProvinceServlet中通过GET方式获取请求，将返回的数据以O（输出）流的方式发送出去,上面代码的ajax.responseXML获取输出的数据，并进行dom操作


public class ProvinceServlet extends HttpServlet { 
 @Override 
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
 throws ServletException, IOException { 
 req.setCharacterEncoding("utf-8"); 
 resp.setCharacterEncoding("utf-8"); 
 String province = req.getParameter("province"); 
 //重新编码 
 province = new String(province.getBytes("ISO-8859-1"),"utf-8"); 
 //设置格式为xml 
 resp.setContentType("text/xml;charset=utf-8"); 
 //获取字符输出流 
 PrintWriter pw = resp.getWriter(); 
 //拼接xml头 
 pw.write("<?xml version='1.0' encoding='UTF-8'?>"); 
 pw.write("<citys>"); 
 if ("湖南".equals(province)) { 
 pw.write("<city>长沙</city>"); 
 pw.write("<city>株洲</city>"); 
 pw.write("<city>湘潭</city>"); 
 pw.write("<city>岳阳</city>"); 
 }else if("广东".equals(province)){ 
 pw.write("<city>广州</city>"); 
 pw.write("<city>深圳</city>"); 
 pw.write("<city>中山</city>"); 
 } 
 pw.write("</citys>"); 
 pw.flush(); 
 pw.close(); 
 } 
}

运行结果如下: