DWR（Direct Web Remoting）是一个用于改善web页面与Java类交互的远程服务器端Ajax开源框架，可以帮助开发人员开发包含AJAX技术的网站。它可以允许在浏览器里的代码使用运行在WEB服务器上的JAVA函数，就像它就在浏览器里一样。
使用DWR首先加入DWR的jar包.我这里用的是2.0.5的.
看代码吧,首先是index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>ajax三级联动</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page"> <script type="text/javascript" src="dwr/engine.js"></script>
<script type="text/javascript" src="dwr/util.js"></script>
<!-- 导入DWR 为Java 对象动态生成的JavaScript 文件-->
<script type="text/javascript" src="dwr/interface/mydwr.js"></script>
<script type="text/javascript" src="jquery-1.8.3.min.js"></script></head>
<script type="text/javascript">
$(function(){
mydwr.findProvince(function(pro){
for(var i=0;i<pro.length;i++){
$(".province").append("<option value="+pro[i].id+">"+pro[i].province+"</option>");
}
});
}); </script>
<body>
省：<select name="province" class="province">
<option value="0">==请选择==</option>
</select>
市：<select name="city" class="city">
<option>==请选择==</option>
</select>
区：<select name="town" class="town">
<option>==请选择==</option>
</select>
</body>
<script type="text/javascript">
$(".province").change(function(){
if($(".province").val()==0){
$(".city option").remove();
$(".city").append("<option value=0>==请选择==</option>");
$(".town option").remove();
$(".town").append("<option value=0>==请选择==</option>");
return;
}
mydwr.findCityById($(this).val(),function(city){
$(".city option").remove();
$(".city").append("<option value=0>==请选择==</option>");
for(var i=0;i<city.length;i++){
$(".city").append("<option value="+city[i].id+">"+city[i].city+"</option>");
}
});
});
$(".city").change(function(){
if($(".city").val()==0){
$(".town option").remove();
$(".town").append("<option value=0>==请选择==</option>");
return;
}
mydwr.findTownById($(this).val(),function(town){
$(".town option").remove();
$(".town").append("<option value=0>==请选择==</option>");
for(var i=0;i<town.length;i++){
$(".town").append("<option value="+town[i].id+">"+town[i].town+"</option>");
}
});
});
</script>
</html>
三个实体类
package cn.yo.entity; import java.util.HashSet;
import java.util.Set; public class Province implements java.io.Serializable { private Integer id;
private String province;
private Set cities = new HashSet(0);
//省略了get,set方法
}
package cn.yo.entity; import java.util.HashSet;
import java.util.Set; public class City implements java.io.Serializable { private Integer id;
private Province province;
private String city;
private Set towns = new HashSet(0);
//省略了get,set方法
}
package cn.yo.entity; public class Town implements java.io.Serializable { private Integer id;
private City city;
private String town;
//省略了get,set方法
}
dao类
package cn.yo.dao; import java.util.List;
import org.hibernate.Session;
import cn.yo.entity.City;
import cn.yo.entity.Province;
import cn.yo.entity.Town; public class ProvinceDao {
//查询全部省
public List<Province> findProvince(){
Session session=HibernateSessionFactory.getSession();
String hql="from Province";
List<Province> province=session.createQuery(hql).list();
if(province.size()>0){
return province;
}
else{
return null;
}
}
//根据省的Id查询该省下的全部市
public List<City> findCityById(int id){
Session session=HibernateSessionFactory.getSession();
String hql="from City c where c.province.id='"+id+"'";
List<City> city=session.createQuery(hql).list();
if(city.size()>0){
return city;
}else{
return null;
}
}
//根据市的Id查询该市下的全部镇
public List<Town> findTownById(int id){
Session session=HibernateSessionFactory.getSession();
String hql="from Town t where t.city='"+id+"'";
List<Town> town=session.createQuery(hql).list();
if(town.size()>0){
return town;
}else{
return null;
}
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- DWR -->
<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>
<init-param>
<param-name>crossDomainSessionSecurity</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>allowScriptTagRemoting</param-name>
<param-value>true</param-value>
</init-param> </servlet>
<servlet-mapping>
<servlet-name>dwr_invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>
dwr.xml:没有他就没有DWR哦,放在web.xml同一目录下
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE dwr PUBLIC
3 "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN"
4 "http://getahead.org/dwr/dwr20.dtd">
5
6 <dwr>
7 <allow>
8 <create javascript="mydwr" creator="new">
9 <param name="class" value="cn.yo.dao.ProvinceDao"/>
10 </create>
11 <convert match="cn.yo.entity.Province" converter="bean"/>
12 <convert match="cn.yo.entity.City" converter="bean"/>
13 <convert match="cn.yo.entity.Town" converter="bean"/>
14 </allow>
15 </dwr>
代码全部贴出,希望能给初学者一点帮助.写的不好,希望大家能提出建议.小弟感激不尽
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