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纯JSP+DWR实现3 级联动下拉选择菜单实现技巧

　　发布时间：2023-07-10 12:52:40　

标签： , 联动,下拉,菜单

网上看到一些例子，对于一个简单的3 级联动，都加上什么Struts, Hibernate诸如此类的框架。这个Ajax联动殊不知和这些框架有什么关系，一个小Demo干嘛整得那么大。
今天我做了一个dwr+jsp做的例子。
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>dwr-invoker</servlet-name>
<servlet-class>
org.directwebremoting.servlet.DwrServlet
</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet>
<servlet-name>SelectServlet</servlet-name>
<servlet-class>com.action.SelectServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
<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>

dwr.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting
2.0//EN" "http://www.getahead.ltd.uk/dwr/dwr20.dtd">
<dwr>

<allow>
<create creator="new" javascript="menu">
<param name="class" value="com.dao.CountryDAO" />
</create>

<convert converter="bean" match="com.vo.Country" />
<convert converter="bean" match="com.vo.Province" />
<convert converter="bean" match="com.vo.City" />
</allow>
</dwr>

test.jsp:

<％@ page language="java" import="java.util.*,com.vo.*"
pageEncoding="GBK"％>
<％@ taglib uri="http://java.sun.com/jstl/core" prefix="c"％>
<html>
<head>
<title>DWR * 联动</title>
<script type='text/javascript'
src='/mutiplyMenu/dwr/interface/menu.js'></script>
<script type='text/javascript' src='/mutiplyMenu/dwr/engine.js'></script>
<script type='text/javascript' src='/mutiplyMenu/dwr/util.js'></script>
</head>
<body>
<script type="text/javascript">
//根据国家id查询所属省或州
function queryProvince()
{
var countryId = $("country").value;
//默认为不选择
if(countryId == 0)
{
${"province"}.options.length=0;
${"city"}.options.length=0;
}
else
{
menu.queryProvinceById(countryId,provinceCallback);
}
}
//根据国家id查询所属省或州的回调函数
function provinceCallback(provinces)
{
${"province"}.options.length=0;
//每次获得新的数据的时候先把每二个下拉框架的长度清0
for(var i=0;i< provinces.length;i ++){
var value = provinces[i].id;
var text = provinces[i].provinceName;
var option = new Option(text, value);
//根据每组value和text标记的值创建一个option对象
try{
$("province").add(option);//将option对象添加到第二个下拉框中
}catch(e){
}
}
//同时关联第 *
var provinceId = ${"province"}.value;
menu.queryCityById(provinceId,cityCallback);
}
//查询所属城市
function queryCity()
{
var provinceId = $("province").value;
menu.queryCityById(provinceId,cityCallback);
}
//查询所属城市回调函数
function cityCallback(citys)
{
//每次获得新的数据的时候先把每三个下拉框架的长度清0
${"city"}.options.length=0;
for(var i=0;i< citys.length;i ++){
var value = citys[i].id;
var text = citys[i].cityName;
var option = new Option(text, value);
//根据每组value和text标记的值创建一个option对象
try{
$("city").add(option);//将option对象添加到第三个下拉框中
}catch(e){
}
}
}
function change1()
{
queryProvince();
}
function change2()
{
queryCity();
}
</script>
<div align="center">
<h3>
<br>
</h3>
<h3>
DWR * 联动演示
</h3>

<select id="country" onchange="change1();">
<option selected="selected" value="0">
请选择
</option>
<％
@SuppressWarnings("unchecked")
List list = (List) request.getAttribute("countrys");
for (int i = 0; i < list.size(); i++)
{
Country temp = (Country) list.get(i);
％>
<option value="<％=temp.getId()％>"><％=temp.getCountryName()％></option>
<％
}
％>
</select>
<select id="province" onchange="change2();">
</select>
<select id="city">
</select>
</div>
</body>
</html>

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纯JSP+DWR实现3 级联动下拉选择菜单实现技巧

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