Ajax實(shí)現(xiàn)二級(jí)聯(lián)動(dòng)菜單
本文實(shí)例為大家分享了ajax二級(jí)聯(lián)動(dòng)菜單的具體代碼，供大家參考，具體內(nèi)容如下
index.jsp
<%@ page language="java" pageencoding="utf-8"%>
<html>
<head>
<title>二級(jí)菜單聯(lián)動(dòng)演示</title>
<script type="text/javascript">
var req;
window.οnlοad=function()
{//頁面加載時(shí)的函數(shù)
}
function change_select(){//當(dāng)?shù)谝粋€(gè)下拉框的選項(xiàng)發(fā)生改變時(shí)調(diào)用該函數(shù)
var province = document.getelementbyid('province').value;
var url = "select?id="+ escape(province);
if(window.xmlhttprequest){
req = new xmlhttprequest();
}else if(window.activexobject){
req = new activexobject("microsoft.xmlhttp");
}
if(req){
req.open("get",url,true);
//指定回調(diào)函數(shù)為callback
req.onreadystatechange = callback;
req.send(null);
}
}
//回調(diào)函數(shù)
function callback(){
if(req.readystate ==4){
if(req.status ==200){
parsemessage();//解析xml文檔
}else{
alert("不能得到描述信息:" + req.statustext);
}
}
}
//解析返回xml的方法
function parsemessage(){
var xmldoc = req.responsexml.documentelement;//獲得返回的xml文檔
var xsel = xmldoc.getelementsbytagname('select');
//獲得xml文檔中的所有<select>標(biāo)記
var select_root = document.getelementbyid('city');
//獲得網(wǎng)頁中的第二個(gè)下拉框
select_root.options.length=0;
//每次獲得新的數(shù)據(jù)的時(shí)候先把每二個(gè)下拉框架的長(zhǎng)度清0
for(var i=0;i<xsel.length;i++){
var xvalue = xsel[i].childnodes[0].firstchild.nodevalue;
//獲得每個(gè)<select>標(biāo)記中的第一個(gè)標(biāo)記的值,也就是<value>標(biāo)記的值
var xtext = xsel[i].childnodes[1].firstchild.nodevalue;
//獲得每個(gè)<select>標(biāo)記中的第二個(gè)標(biāo)記的值,也就是<text>標(biāo)記的值
var option = new option(xtext, xvalue);
//根據(jù)每組value和text標(biāo)記的值創(chuàng)建一個(gè)option對(duì)象
try{
select_root.add(option);//將option對(duì)象添加到第二個(gè)下拉框中
}catch(e){
}
}
}
</script>
</head>
<body>
<div align="center">
<form name="form1" method="post" action="">
<table width="70%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="center">
二級(jí)聯(lián)動(dòng)示例
</td>
</tr>
<tr>
<td>
<select name="province" id="province" onchange="change_select()">
<!--第一個(gè)下拉菜單-->
<option value="0">
請(qǐng)選擇
</option>
<option value="1">
北京
</option>
<option value="2">
天津
</option>
<option value="3">
山東
</option>
</select>
<select name="city" id="city">
<!--第二個(gè)下拉菜單-->
<option value="0">
請(qǐng)選擇
</option>
</select>
</td>
</tr>
<tr>
<td>
</td>
<tr>
</table>
</form>
</div>
</body>
</html>
selectservlet.java
package com;
import java.io.ioexception;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
/***
*
* @author zdw
*
*/
public class selectservlet extends httpservlet
{
private static final long serialversionuid = 1l;
public selectservlet()
{
super();
}
public void destroy()
{
super.destroy();
}
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception
{
// response.setcharacterencoding("gbk");
response.setcontenttype("text/xml");
response.setheader("cache-control", "no-cache");
request.setcharacterencoding("gbk");
response.setcharacterencoding("utf-8");
string targetid = request.getparameter("id").tostring();
system.out.println(targetid);
// 獲得請(qǐng)求中參數(shù)為id的值
string xml_start = "<selects>";
string xml_end = "</selects>";
string xml = "";
if (targetid.equalsignorecase("0"))
{
xml = "<select><value>0</value><text>請(qǐng)選擇</text></select>";
} else if (targetid.equalsignorecase("1"))
{
xml = "<select><value>1</value><text>昌平</text></select>";
xml += "<select><value>2</value><text>豐臺(tái)</text></select>";
xml += "<select><value>3</value><text>海淀</text></select>";
xml += "<select><value>4</value><text>朝陽</text></select>";
} else if (targetid.equalsignorecase("2"))
{
xml = "<select><value>1</value><text>塘沽區(qū)</text></select>";
xml += "<select><value>2</value><text>漢沽區(qū)</text></select>";
xml += "<select><value>3</value><text>大港區(qū)</text></select>";
xml += "<select><value>4</value><text>東麗區(qū)</text></select>";
} else
{// 如果是3,則返回下面的字符
xml = "<select><value>1</value><text>濟(jì)南</text></select>";
xml += "<select><value>2</value><text>青島</text></select>";
xml += "<select><value>3</value><text>淄博</text></select>";
xml += "<select><value>4</value><text>棗莊</text></select>";
}
string last_xml = xml_start + xml + xml_end;
response.getwriter().write(last_xml);
}
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception
{
doget(request, response);
}
public void init() throws servletexception
{
}
}
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> <servlet-name>selectservlet</servlet-name> <servlet-class>com.selectservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>selectservlet</servlet-name> <url-pattern>/select</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持碩編程。
學(xué)習(xí)AJAX