%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
html>
head>
script type="text/javascript" language="javaScript">
var xmlHttp = false; //全局變量，用于記錄XMLHttpRequest對象
function createXMLHttpRequest() {
if(window.ActiveXObject) { //Internet Explorer時，創(chuàng)建XMLHttpRequest對象的方法
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
try { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
//舊版本的Internet Explorer，創(chuàng)建XMLHttpRequest對象
} catch(e) {
window.alert("創(chuàng)建XMLHttpRequest對象錯誤"+e);
}
}
} else if(window.XMLHttpRequest) { //mozilla時，創(chuàng)建XMLHttpRequest對象的方法
xmlHttp = new XMLHttpRequest();
}
if(!(xmlHttp)) { //未成功創(chuàng)建XMLHttpRequest對象
window.alert("創(chuàng)建XMLHttpRequest對象異常！");
}
}
//下拉列表項改變時的操作
function proChange(objVal) {
createXMLHttpRequest(); //創(chuàng)建XMLHttpRequest對象
document.getElementById("city").length = 1; //根據(jù)ID獲取指定元素，并賦值
xmlHttp.onreadystatechange = cityList; //指定onreadystatechange處理函數(shù)
var url="CityByXMLServlet?province="+objVal; //請求的URL地址
xmlHttp.open("POST",url,true);
xmlHttp.send(null);
}
function cityList() { //onreadystatechange的處理函數(shù)
if(xmlHttp.readyState==4) {
if(xmlHttp.status==200) {
parseXML(xmlHttp.responseXML); //解析服務(wù)器返回的XML數(shù)據(jù)
}
}
}
//解析xml信息，以添加地市
function parseXML(xmlDoc) {
var len = xmlDoc.getElementsByTagName("city");
//獲取XML數(shù)據(jù)中所有的“city”元素對象集合
var _citySel = document.getElementById("city"); //根據(jù)ID獲取頁面中的select元素
for(var i=0;ilen.length;i++) { //遍歷XML數(shù)據(jù)并給select元素添加選項
var opt = document.createElement("OPTION"); //創(chuàng)建option對象
opt.text = xmlDoc.getElementsByTagName("city")[i].firstChild.data;
//指定新創(chuàng)建元素的text屬性值
opt.value = xmlDoc.getElementsByTagName("city")[i].firstChild.data;
//指定新創(chuàng)建元素的value屬性值
_citySel.add(opt); //為select元素添加option
}
}
/script>
title>動態(tài)加載組合框/title>
/head>
body>
table align="center" border=1 width="320">
tr>
td>省份：/td>
td>
select id="province" onChange="proChange(this.value);" style="width:85">
option value="gd">廣東/option>
option value="gx">廣西/option>
option value="hn">湖南/option>
option value="hb">湖北/option>
option value="ah">安徽/option>
/select>
/td>
/tr>
tr>
td>城市：/td>
td>
select id="city" style="width:85">
option value="">--請選擇--/option>
/select>
/td>
/tr>
/table>
/body>
/html>
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
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 CityByXMLServlet
*/
@WebServlet("/CityByXMLServlet")
public class CityByXMLServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String CONTENT_TYPE = "text/xml; charset=UTF-8";
/**
* @see HttpServlet#HttpServlet()
*/
public CityByXMLServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType(CONTENT_TYPE); //設(shè)置服務(wù)器響應(yīng)類型
String province =request.getParameter("province");
StringBuffer city = new StringBuffer("citys>"); //記錄返回XML串的對象
if("gx".equals(province)){
List list=cityInit(); //獲取城市列表
for(int i=0;ilist.size();i++){
city.append("city>"+list.get(i)+"/city>");
}
}else if("hn".equals(province)){
List list = cityInit1(); //獲取城市列表
for(int j=0;jlist.size();j++){
city.append("city>"+list.get(j)+"/city>");
}
}else if("hb".equals(province)){
List list = cityInit2(); //獲取城市列表
for(int j=0;jlist.size();j++){
city.append("city>"+list.get(j)+"/city>");
}
}
city.append("/citys>");
PrintWriter out = response.getWriter();
out.println(city.toString());
out.flush(); //輸出流刷新
out.close(); //關(guān)閉輸出流
}
/*
* 初始化城市
*/
public ListString> cityInit2() {
ListString> cityList = new ArrayListString>();
//添加城市列表
cityList.add("武漢");
cityList.add("襄陽");
cityList.add("黃岡");
cityList.add("荊門");
cityList.add("十堰");
cityList.add("黃石");
return cityList;
}
public ListString> cityInit(){
ListString> cityList = new ArrayListString>();
//添加城市列表
cityList.add("南寧");
cityList.add("桂林");
cityList.add("北海");
cityList.add("河池");
cityList.add("梧州");
cityList.add("玉林");
return cityList;
}
public ListString> cityInit1() {
ListString> cityList = new ArrayListString>();
//添加城市列表
cityList.add("長沙");
cityList.add("湘潭");
cityList.add("岳陽");
cityList.add("常德");
cityList.add("衡陽");
cityList.add("邵陽");
return cityList;
}
/**
*當前Servelt的初始化方法. br>
*
* @throws ServletException發(fā)生ServletExceptio時拋出
*/
public void init() throws ServletException {
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
?xml version="1.0" encoding="UTF-8"?>
web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.4">
servlet>
servlet-name>CityByXMLServlet/servlet-name>
servlet-class>servlet.CityByXMLServlet/servlet-class>!--類的位置 -->
/servlet>
servlet-mapping>
servlet-name>CityByXMLServlet/servlet-name>!--你創(chuàng)建的類名 -->
url-pattern>/CityByXMLServlet/url-pattern>
/servlet-mapping>
以上所述是小編給大家介紹的Ajax實現(xiàn)動態(tài)加載組合框的實例代碼，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言，小編會及時回復(fù)大家的！
