純JSP+DWR實現三級聯動下拉選擇菜單實現技巧

最後更新：2018-12-08 來源：互聯網

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網上看到一些例子，對於一個簡單的三級聯動，都加上什麼Struts, Hibernate諸如此類的架構。這個Ajax聯動殊不知和這些架構有什麼關係，一個小Demo幹嘛整得那麼大。

今天我做了一個dwr+jsp做的例子。
web.xml: 複製代碼代碼如下:<?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: 複製代碼代碼如下:<?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>

<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: 複製代碼代碼如下:<%@ page language="java" import="java.util.*,com.vo.*"
pageEncoding="GBK"%>
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c"%>
<html>
<head>
<title>DWR三級聯動</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">
//根據國家id查詢所屬省或州
function queryProvince()
{
var countryId = $("country").value;
//預設為不選擇
if(countryId == 0)
{
${"province"}.options.length=0;
${"city"}.options.length=0;
}
else
{
menu.queryProvinceById(countryId,provinceCallback);
}
}
//根據國家id查詢所屬省或州的回呼函數
function provinceCallback(provinces)
{
${"province"}.options.length=0;
//每次獲得新的資料的時候先把每二個下拉架構的長度清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);
//根據每組value和text標記的值建立一個option對象
try{
$("province").add(option);//將option對象添加到第二個下拉框中
}catch(e){
}
}
//同時關聯第三級
var provinceId = ${"province"}.value;
menu.queryCityById(provinceId,cityCallback);
}
//查詢所屬城市
function queryCity()
{
var provinceId = $("province").value;
menu.queryCityById(provinceId,cityCallback);
}
//查詢所屬城市回呼函數
function cityCallback(citys)
{
//每次獲得新的資料的時候先把每三個下拉架構的長度清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);
//根據每組value和text標記的值建立一個option對象
try{
$("city").add(option);//將option對象添加到第三個下拉框中
}catch(e){
}
}
}
function change1()
{
queryProvince();
}
function change2()
{
queryCity();
}
</script>
<div align="center">
<h3>
<br>
</h3>
<h3>
DWR三級聯動示範
</h3>

<select id="country" onchange="change1();">
<option selected="selected" value="0">
請選擇
</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>

servlet,dao就不帖了，想瞭解的可以去下載源碼

本文章原先以中文撰寫並發佈於 aliyun.com，亦設英文版本，僅作資訊用途。本網站不對文章的準確性，完整性或可靠性或其任何翻譯作出任何明示或暗示的陳述或保證。如對該文章有任何疑慮或投訴，請傳送電郵至 info-contact@alibabacloud.com 並提供相關疑慮或投訴的詳細說明。職員會於 5 個工作天內與您聯絡，一經驗證之後，即會刪除該侵權內容。

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