本文实例为大家分享了AJAX二级联动效果的具体代码，供大家参考，具体内容如下
Ajax.js
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var createAjax = function(){
var ajax = null;
try{
ajax = new ActiveXObject("microsoft.xmlhttp");
}catch(e1){
try{
ajax = new XMLHttpRequest();
}catch(e2){
alert("请换掉你的浏览器");
}
}
return ajax;
}
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test3.xml
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<%@ page language="Java" contentType="text/html; charset=UTF-8"
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>
<script type="text/javascript" src="js/ajax.js"></script>
<base href="<%=basePath%>" rel="external nofollow" >
<title>??</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">
</head>
<body>
<select id="province">
<option>请选择省份</option>
<option>江苏</option>
<option>江西</option>
</select>
<select id="city">
<option>请选择城市</option>
</select>
<script type="text/javascript">
document.getElementById("province").onchange = function(){
var cityElement = document.getElementById("city");
cityElement.options.length = 1;
/* 拿到第一个下拉框中选中的值 */
var index = this.selectedIndex;
var optionElement = this[index];
var optionValue = optionElement.innerHTML;
/* 把这个值发送给服务器 */
var ajax = createAjax();
var url = "${pageContext.request.contextPath }/SelectServlet?time="+new Date().getTime();
var method = "POST";
ajax.open(method , url);
ajax.setRequestHeader("content-type" , "application/x-www-form-urlencoded");
var content = "province=" + optionValue;
ajax.send(content);
/* -----接收相应的数据----- */
ajax.onreadystatechange = function(){
if(ajax.readyState == 4 && ajax.status == 200){
/* 拿到xml */
var xmlDocument = ajax.responseXML;
/* 用xml的解析方式拿到城市根据标签名称 */
var cityArray = xmlDocument.getElementsByTagName("cityOption");
for (var i = 0; i < cityArray.length; i++){
/* 用xml的解析方式拿到城市的值 */
var city = cityArray[i].firstChild.nodeValue;
var option = document.createElement("option");
option.innerHTML = city;
cityElement.appendChild(option);
}
}
}
}
</script>
</body>
</html>
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SelectServlet.java
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package com.newtouch.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class SelectServlet
*/
@WebServlet("/SelectServlet")
public class SelectServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public SelectServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
// 这里是text/xml是把数据放到了xml中
response.setContentType("text/xml;charset=utf-8");
String province = request.getParameter("province");
response.getWriter().write("<?xml version='1.0' encoding='utf-8' ?>");
response.getWriter().write("<root>");
if ("江苏".equals(province)) {
response.getWriter().write("<cityOption>1</cityOption>");
response.getWriter().write("<cityOption>2</cityOption>");
response.getWriter().write("<cityOption>3</cityOption>");
response.getWriter().write("<cityOption>4</cityOption>");
} else if ("江西".equals(province)) {
response.getWriter().write("<cityOption>一</cityOption>");
response.getWriter().write("<cityOption>二</cityOption>");
response.getWriter().write("<cityOption>三</cityOption>");
response.getWriter().write("<cityOption>四</cityOption>");
}
response.getWriter().write("</root>");
}
}
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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服务器之家。
原文链接：http://www.cnblogs.com/ShaoXin/p/7412467.html