JSP自定义标签无限极（数据来源于数据库）下拉联动
说明：这个工程的环境需要：JSP自定义标签、dwr，这个例子提供了几个实际应用的例子，包括了修改时候自动选中等。
首先看看web.xml的配置：
1、
<?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">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>dwr-remote</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-mapping>
<servlet-name>dwr-remote</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
<jsp-config>
<taglib>
<taglib-uri>/tag</taglib-uri>
<taglib-location>/WEB-INF/ne.tld</taglib-location>
</taglib>
</jsp-config>
</web-app>
2、dwr的配置文件dwr.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "dwr30.dtd"> <dwr> <allow> <create creator="new" javascript="LINK"> <param name="class" value="com.core.LinkageAdapter"></param> </create> </allow> </dwr>
3、tag.xml，jsp自定义标签的配置文件
<?xml version="1.0" encoding="utf-8"?> <taglib> <tlib-version>1.0</tlib-version> <jsp-version>1.2</jsp-version> <uri>/tag</uri> <tag> <name>select</name> <body-content>empty</body-content> <info>下拉框标签</info> <tag-class>com.tag.link.SelectTag</tag-class> <attribute> <description>select框的name属性</description> <required>true</required> <rtexprvalue>true</rtexprvalue> <name>name</name> </attribute> <attribute> <description>select框的sql属性</description> <required>true</required> <rtexprvalue>true</rtexprvalue> <name>sql</name> </attribute> <attribute> <name>bind</name> <description>绑定下一级别的ID属性</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>bindSelectValue</name> <description>绑定联动的下拉框的值，当联动的下拉框的值为当前的值的时候选中</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>bindSql</name> <description>下一级别的查询SQL语句</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>select:link</name> <body-content>empty</body-content> <info>联动的子级标签</info> <tag-class>com.tag.link.LinkSelect</tag-class> <attribute> <description>select框的name属性</description> <required>true</required> <rtexprvalue>true</rtexprvalue> <name>name</name> </attribute> <attribute> <name>bind</name> <description>绑定下一级别的ID属性</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>bindSql</name> <description>绑定下一级别的ID属性</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>bindSelectValue</name> <description>选中该下拉框的属性值</description> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>
4、有了上面的配置后，在jsp页面调用如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="tag" uri="/tag" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>下拉联动的测试</title>
<style type="text/css">
*{
padding: 15px;
}
</style>
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<meta http-equiv="expires" content="0" />
<script type='text/javascript' src='<%=request.getContextPath() %>/dwr/interface/LINK.js'></script>
<script type='text/javascript' src='<%=request.getContextPath() %>/dwr/engine.js'></script>
<script type='text/javascript' src='<%=request.getContextPath() %>/dwr/util.js'></script>
</head>
<body>
<fieldset>
<legend>省县乡级联</legend>
<tag:select name="province" sql="select povinceid,povincename from povince" bind="city"
bindSql="select cityid,cityname from city where father = " />
<tag:select:link name="city" bind="area"
bindSql="select areaid,areaname from area where father = "/>
<tag:select:link name="area" />
</fieldset>
<fieldset>
<legend>省县级联</legend>
<tag:select name="sheng" sql="select povinceid,povincename from povince" bind="xian" bindSql="select cityid,cityname from city where father = "/>
<tag:select:link name="xian" />
</fieldset>
<fieldset>
<legend>县乡级联</legend>
<tag:select name="xianxian" sql="select cityid,cityname from city " bind="xiangxiang" bindSql="select areaid,areaname from area where father = "/>
<tag:select:link name="xiangxiang" />
</fieldset>
<script type="text/javascript" src="<%=request.getContextPath() %>/js/select.js"></script>
</body>
</html>
5、请注意查看标签调用的那部分，这个页面就实现了3组的联动，详细的就不说了，附上可以运行的工程。
详细也可以看
http://haiyangyiba.iteye.com/admin/blogs/650250
这里有详细的信息。