java完成的二級聯動菜單後果。本站提示廣大學習愛好者：（java完成的二級聯動菜單後果）文章只能為提供參考，不一定能成為您想要的結果。以下是java完成的二級聯動菜單後果正文
本文實例講述了java完成的二級聯動菜單後果。分享給年夜家供年夜家參考，詳細以下：
JSP代碼：
<%@ page language="java" pageEncoding="UTF-8"%>
<html>
<head>
<title>二級菜單聯動演示</title>
<script type="text/javascript">
var req;
window.onload=function()
{//頁面加載時的函數
}
function Change_Select(){//當第一個下拉框的選項產生轉變時挪用該函數
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);
//指定回調函數為callback
req.onreadystatechange = callback;
req.send(null);
}
}
//回調函數
function callback(){
if(req.readyState ==4){
if(req.status ==200){
parseMessage();//解析XML文檔
}else{
alert("不克不及獲得描寫信息:" + req.statusText);
}
}
}
//解析前往xml的辦法
function parseMessage(){
var xmlDoc = req.responseXML.documentElement;//取得前往的XML文檔
var xSel = xmlDoc.getElementsByTagName('select');
//取得XML文檔中的一切<select>標志
var select_root = document.getElementById('city');
//取得網頁中的第二個下拉框
select_root.options.length=0;
//每次取得新的數據的時刻先把每二個下拉框架的長度清0
for(var i=0;i<xSel.length;i++){
var xValue = xSel[i].childNodes[0].firstChild.nodeValue;
//取得每一個<select>標志中的第一個標志的值,也就是<value>標志的值
var xText = xSel[i].childNodes[1].firstChild.nodeValue;
//取得每一個<select>標志中的第二個標志的值,也就是<text>標志的值
var option = new Option(xText, xValue);
//依據每組value和text標志的值創立一個option對象
try{
select_root.add(option);//將option對象添加到第二個下拉框中
}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">
二級聯動示例
</td>
</tr>
<tr>
<td>
<select name="province" id="province" onChange="Change_Select()">
<!–第一個下拉菜單–>
<option value="0">
請選擇
</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">
<!–第二個下拉菜單–>
<option value="0">
請選擇
</option>
</select>
</td>
</tr>
<tr>
<td>
</td>
<tr>
</table>
</form>
</div>
</body>
</html>
Java代碼：
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);
// 取得要求中參數為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>豐台</text></select>";
xml += "<select><value>3</value><text>海澱</text></select>";
xml += "<select><value>4</value><text>旭日</text></select>";
} else if (targetId.equalsIgnoreCase("2"))
{
xml = "<select><value>1</value><text>塘沽區</text></select>";
xml += "<select><value>2</value><text>漢沽區</text></select>";
xml += "<select><value>3</value><text>年夜港區</text></select>";
xml += "<select><value>4</value><text>東麗區</text></select>";
} else
{// 假如是3,則前往上面的字符
xml = "<select><value>1</value><text>濟南</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
{
}
}
XML代碼：
<?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>
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願望本文所述對年夜家java法式設計有所贊助。
