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AJAX级联菜单
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AJAX级联菜单实例
说明 ajax级联菜单，例如，一级菜单选择中国，二级菜单列出中国城市；一级菜单选择美国，二级菜单列出美国城市。
数据库脚本 count.sql
DROP TABLE IF EXISTS `country`;
CREATE TABLE `country` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(50) default NULL,
`city` varchar(50) default NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
insert into country values(1,'中国','沈阳') ;
insert into country values(2,'中国','北京') ;
insert into country values(3,'美国','洛杉矶') ;
insert into country values(4,'美国','纽约') ;
DAO
package edu.syict.www.dao;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import edu.syict.www.HibernateSessionFactory;
public class DBOperator {
@SuppressWarnings("unchecked")
public List queryByName(String name){
Session session = HibernateSessionFactory.getSession();
List list=null ;
String hql="SELECT co.city FROM Country AS co WHERE co.name=?" ;
System.out.println(hql+name);
Transaction tx = null;
try {
tx = session.beginTransaction();
Query query=session.createQuery(hql) ;
query.setString(0, name) ;
list=query.list() ;
System.out.println("数据库中记录个数:"+list.size()) ;
tx.commit() ;
} catch (HibernateException e) {
if (tx != null)
tx.rollback();
throw e;
}finally{
session.close();
}
return list ;
}
}
Bean类（Hibernate反向工程）Country.java
package edu.syict.www.POJO;
@SuppressWarnings("serial")
public class Country implements java.io.Serializable {
private Integer id;
private String name;
private String city;
public Country() {
}
public Country(String name, String city) {
this.name = name;
this.city = city;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getCity() {
return this.city;
}
public void setCity(String city) {
this.city = city;
}
}
Country.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="edu.syict.www.POJO.Country" table="country" catalog="test">
<id name="id" type="java.lang.Integer">
<column name="id" />
<generator class="identity" />
</id>
<property name="name" type="java.lang.String">
<column name="name" length="50" />
</property>
<property name="city" type="java.lang.String">
<column name="city" length="50" />
</property>
</class>
</hibernate-mapping>
JSP页面
<%@ page language="java" pageEncoding="UTF-8"%>
<%@ page import="java.util.*" %>
<%@ page import="edu.syict.www.dao.*" %>
<%@ page import="edu.syict.www.POJO.*" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'menu.jsp' starting page</title>
</head>
<body>
<%
Country c=null ;
DBOperator dbo=new DBOperator() ;
List listname=dbo.query("SELECT DISTINCT co.name FROM Country AS co") ;
List listcity=dbo.query("SELECT DISTINCT co.city FROM Country AS co") ;
%>
<center>
<script type="text/javascript">
var XMLHttpReq;
var currentSort;
//创建XMLHttpRequest对象
function createXMLHttpRequest() {
if(window.XMLHttpRequest) { //Mozilla 浏览器
XMLHttpReq = new XMLHttpRequest();
}
else if (window.ActiveXObject) { // IE浏览器
try {
XMLHttpReq = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
}
//发送请求函数
function sendRequest(url) {
createXMLHttpRequest();
XMLHttpReq.open("GET", url, true);
XMLHttpReq.onreadystatechange = processResponse;//指定响应函数
XMLHttpReq.send(null); // 发送请求
}
// 处理返回信息函数
function processResponse() {
if (XMLHttpReq.readyState == 4) { // 判断对象状态
if (XMLHttpReq.status == 200) { // 信息已经成功返回，开始处理信息XMLHttpReq.status == 200
updateMenu();
} else { //页面不正常
alert("您所请求的页面有异常。");
}
}
}
//更新菜单函数
function updateMenu() {
var res=XMLHttpReq.responseXML.getElementsByTagName("res") ;
//alert("res===="+res[0].firstChild.nodeValue);
/**下面是用innerHTML输出控件内容的一般用法**/
//var subMenu = "";
//for(var i = 0; i < res.length; i++) {
// subMenu = subMenu + " " + res[i].firstChild.data + "";
//}
//currentSort.innerHTML = subMenu;
var list = document.all.list;
list.options.length=0;
list.add(new Option("---请选择---",""));
for(var i=0;i<res.length;i++){
list.add(new Option(res[i].firstChild.nodeValue,res[i].firstChild.nodeValue));
}
}
// 创建级联菜单函数
function showSubMenu(obj) {
//currentSort =document.getElementById(obj);
//currentSort.parentNode.style.display = "";
sendRequest("menujsp.jsp?sort=" + obj);
/**下面这一句的作用是：每次选择后回到第一个选项**/
//document.all.mli.options[0].selected=true;
}
</script>
<select name="mli" onchange="showSubMenu(this.options[this.options.selectedIndex].value)" style="width:150px;">
<option value="">---bbb---</option>
<%
for(int i=0;i<listname.size();i++){
//c=(Country)listname.get(i) ;
out.println("<option value='"+listname.get(i)+"'>"+listname.get(i)+"</option>") ;
}
%>
</select>
<select name="list" style="width:100px;">
<option value="">---aaa---</option>
<%
for(int i=0;i<listcity.size();i++){
out.println("<option value='"+listcity.get(i)+"'>"+listcity.get(i)+"</options>") ;
}
%>
</select>
<br>
</center>
</body>
</html>
JSP页面后台
<%@ page language="java" pageEncoding="UTF-8"%>
<%@ page import="java.util.*" %>
<%@ page import="edu.syict.www.dao.*" %>
<%@ page import="edu.syict.www.POJO.*" %>
<%
response.setContentType("text/xml; charset=UTF-8");
response.setHeader("Cache-Control","no-cache");
String sort=request.getParameter("sort") ;
sort=new String(sort.getBytes("ISO8859-1"),"GB2312") ;
System.out.println("转换编码后sort:"+sort) ;
DBOperator dbo=new DBOperator() ;
List cityes=new ArrayList() ;
try{
cityes=dbo.queryByName(sort) ;
}catch(Exception e){
e.printStackTrace() ;
}
out.println("<response>");
for(int i=0;i<cityes.size();i++){
out.println("<res>"+cityes.get(i).toString()+"</res>") ;
System.out.println(cityes.get(i)) ;
}
out.println("</response>");
%>
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2010-12-03
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