Ajax动态更新上拉列表
日期：2014-05-16 浏览次数：20703 次
Ajax动态更新下拉列表
动态更新下拉列表是交互性Web应用的必备功能，可以为用户使用带去很大方便，希望以下示例能给学习Ajax的朋友们一些启示。
JSP页面：select-tag.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%
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%>">
<title>My JSP 'select-tag.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<script type="text/javascript">
var xmlHttp;
function createXMLHttpRequest(){
if(window.ActiveXObject){
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp=new XMLHttpRequest();
}
}
function updateSelect(){
var selected=document.all.slt1.value;
createXMLHttpRequest();
xmlHttp.onreadystatechange=processor;
xmlHttp.open("GET","CreateXML?selected="+selected);
xmlHttp.send(null);
}
function processor(){
var result;
if(xmlHttp.readyState==4){
if(xmlHttp.status==200){
result=xmlHttp.responseXML.getElementsByTagName("city");
while(document.all.slt2.options.length>0){
document.all.slt2.removeChild(document.all.slt2.childNodes[0]);
}
for(var i=0;i<result.length;i++){
var option=document.createElement("OPTION");
option.text=result[i].childNodes[0].childNodes[0].nodeValue;
option.value=result[i].childNodes[1].childNodes[0].nodeValue;
document.all.slt2.options.add(option);
}
}
}
}
</script>
<body>
This is my JSP page. <br>
<p>请选择省份：
<select id="slt1" onChange="updateSelect()">
<option value="1">陕西</option>
<option value="2">湖南</option>
</select>
城市：
<select id="slt2">
<option>请选择城市</option>
</select>
</body>
</html>
配置文件：web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>CreateXML</servlet-name>
<servlet-c
动态更新下拉列表是交互性Web应用的必备功能，可以为用户使用带去很大方便，希望以下示例能给学习Ajax的朋友们一些启示。
JSP页面：select-tag.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%
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%>">
<title>My JSP 'select-tag.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<script type="text/javascript">
var xmlHttp;
function createXMLHttpRequest(){
if(window.ActiveXObject){
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp=new XMLHttpRequest();
}
}
function updateSelect(){
var selected=document.all.slt1.value;
createXMLHttpRequest();
xmlHttp.onreadystatechange=processor;
xmlHttp.open("GET","CreateXML?selected="+selected);
xmlHttp.send(null);
}
function processor(){
var result;
if(xmlHttp.readyState==4){
if(xmlHttp.status==200){
result=xmlHttp.responseXML.getElementsByTagName("city");
while(document.all.slt2.options.length>0){
document.all.slt2.removeChild(document.all.slt2.childNodes[0]);
}
for(var i=0;i<result.length;i++){
var option=document.createElement("OPTION");
option.text=result[i].childNodes[0].childNodes[0].nodeValue;
option.value=result[i].childNodes[1].childNodes[0].nodeValue;
document.all.slt2.options.add(option);
}
}
}
}
</script>
<body>
This is my JSP page. <br>
<p>请选择省份：
<select id="slt1" onChange="updateSelect()">
<option value="1">陕西</option>
<option value="2">湖南</option>
</select>
城市：
<select id="slt2">
<option>请选择城市</option>
</select>
</body>
</html>
配置文件：web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>CreateXML</servlet-name>
<servlet-c
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