纯JSP+DWR实现三级联动下拉选择菜单实现技巧-巨人网络通讯

纯JSP+DWR实现三级联动下拉选择菜单实现技巧

网上看到一些例子，对于一个简单的三级联动，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:

复制代码代码如下:

 
?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:

复制代码代码如下:

 
?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> 
!-- 没有它DWR什么也做不了 --> 
allow> 
create creator="new" javascript="menu"> 
param name="class" value="com.dao.CountryDAO" /> 
/create> 
!-- 要转换的Bean --> 
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:

复制代码代码如下:

 
%@ page language="java" import="java.util.*,com.vo.*" 
pageEncoding="GBK"%> 
%@ taglib uri="http://java.sun.com/jstl/core" prefix="c"%> 
html> 
head> 
title>DWR三级联动/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){ 
} 
} 
//同时关联第三级 
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三级联动演示 
/h3> 
!-- 我都奇怪了，我的c>标签在这里不能用 --> 
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> 