Struts2 DoubleSelect标签的使用-出家如初,成佛有余

Struts2本身提供了级联下拉选择框标签，这对简化诸如省份/城市这样的典型需求的操作是大有好处的，同时也有利于架构的统一，没有必要引入一大堆的javascript代码，使用方法如下：

1、Action层

DoubleListAction.java

package com.mobilesoft.esales.webapp.action;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.log4j.Logger;

import com.mobilesoft.framework.tree.model.FileWrapper;
import com.mobilesoft.framework.tree.model.OssCategory;
import com.mobilesoft.framework.tree.service.TreeService;

public class DoubleListAction extends BaseAction {
    /**
     * Logger for this class
     */
    private static final Logger logger = Logger.getLogger(DoubleListAction.class);

    public String execute() {
        Map map=new HashMap();
        ArrayList list1=new ArrayList();
        list1.add("11");
        list1.add("12");
        list1.add("13");
        map.put("1", list1);
        ArrayList list2=new ArrayList();
        list2.add("21");
        list2.add("22");
        list2.add("23");
        map.put("2", list2);
        ArrayList list3=new ArrayList();
        list3.add("31");
        list3.add("32");
        list3.add("33");
        map.put("3", list3);
        getRequest().setAttribute("map", map);
        return SUCCESS;
    }

    public String doubleSelectTest(){
        Map map=new HashMap();
        ArrayList list1=new ArrayList();
        list1.add("11");
        list1.add("12");
        list1.add("13");
        map.put("1", list1);
        ArrayList list2=new ArrayList();
        list2.add("21");
        list2.add("22");
        list2.add("23");
        map.put("2", list2);
        ArrayList list3=new ArrayList();
        list3.add("31");
        list3.add("32");
        list3.add("33");
        map.put("3", list3);
        getRequest().setAttribute("map", map);
        return SUCCESS;
    }
    public String doubleSelectPost(){

        Map map=getRequest().getParameterMap();
        Set set=map.entrySet();
        Iterator iterator=set.iterator();
        while(iterator.hasNext()){
            Map.Entry mapEntry=(Map.Entry)iterator.next();
            logger.fatal("The key is: "+mapEntry.getKey()+",value is :"+mapEntry.getValue());
        }
        getRequest().setAttribute("map", map);
        return SUCCESS;
    }

}

2、页面

doubleslect.jsp

<%@ taglib prefix="s" uri="/struts-tags" %>
<%@ page language="java" errorPage="/error.jsp" pageEncoding="GBK" contentType="text/html;charset=GBK" %>
<html>
<head>
    <title>Struts 2 Cool Tags - <s:doubeselect/ ></title>
    <s:head />
</head>
<body>
<h2>Doubleselect Tag Example</h2>
<s:form action="doubleSelectPost" name="form1">
Doubleselect演示1
<s:set name="technology"
     value="#{
         'Java': {'Spring', 'Hibernate', 'Struts 2'},
         '.Net': {'Linq', ' ASP.NET 2.0'},
         'Database': {'Oracle', 'SQL Server', 'DB2', 'MySQL'}
         }" />
<s:doubleselect label="技术选择"
list="#technology.keySet()"
name="doubleselect1"
doubleName="techdetail"
formName="form1"
doubleList="#technology[top]" />
<br/><br/>
Doubleselect演示数据演示2：
<s:set name="mymap" value="#request.map"/>
<s:doubleselect list="#request.map.keySet()"
                doubleName="mymap1"
                name="doubleselect2"
                formName="form1"
                doubleList="#request.map[top]"
                label="Map Test" />

<s:submit/>
</s:form>
</body>
</html>

doubleselectpost.jsp

<%@ taglib prefix="s" uri="/struts-tags" %>
<%@ page language="java" errorPage="/error.jsp" pageEncoding="GBK" contentType="text/html;charset=GBK" %>
<html>
<head>
    <title>Struts 2 Cool Tags - <s:doubeselect/ ></title>
    <s:head />
</head>
<body>
<h2>Doubleselect Tag Example</h2>
<s:form name="form1">
<table border="0" cellspacing="0" cellpadding="1">
<tr>
  <th>参数值</th>
</tr>
<s:iterator value="#request.map.keySet()" status="keys">
    <tr>
        <td><s:property/></td>
    </tr>
</s:iterator>
</s:form>
</body>
</html>

3、struts.xml配置文件

<action name="doubleSelectTest" method="doubleSelectTest" class="com.mobilesoft.esales.webapp.action.DoubleListAction">
    <result name="success">test/doubleselect.jsp</result>
</action>
<action name="doubleSelectPost" method="doubleSelectPost" class="com.mobilesoft.esales.webapp.action.DoubleListAction">
    <result name="success">test/doubleselectpost.jsp</result>
</action>

4、级联下拉框间的换行<br >问题

缺省情况下，两个级联下拉框间是换行的，Struts2采用Freemarker来做模板，可以通过修改模板来定制标签缺省的树形。参看“Struts2中Datetimepicker控件的中文问题”中的方法，也即：

修改struts.mxl，增加如下内容。

注意在struts2-core-2.0.11.jar/org/apache/struts2/default.properties中有几个与Freemarker对应的配置参数：

struts.ui.theme=xhtml
struts.ui.templateDir=template
#sets the default template type. Either ftl, vm, or jsp
struts.ui.templateSuffix=ftl

覆盖缺省的静态文件

在resource目录（与WEB-INF同级或WEB-INF下）创建struts目录,并：

解压struts2-core-2.0.11.jar:/org/apache/struts2/static/ to /struts/

解压struts2-core-2.0.11.jar:/template/simple/ to /struts/simple/

解压struts2-core-2.0.11.jar:/template/xhtml/ to /struts/xhtml/

解压struts2-core-2.0.11.jar:/template/css_xhtml/ to /struts/css_xhtml/

解压struts2-core-2.0.11.jar:/template/ajax/ to /struts/ajax/

解压struts2-core-2.0.11.jar:/template/archive/ to /struts/archive

最后的目录结构如下：

struts/
– ajax/
– archive/
– css_xhtml/
– dojo/
– nls/
– src/
– animation/
– …
– xml/
– struts/
– widget/
– widgets/
– niftycorners/
– simple/
– xhtml/