struts2杂记(一)——使用doubleSelect

叁歲伎倆 2022-07-14 09:44 134阅读 0赞

## 一、前言 ##

这段时间忙的要死，做项目，学框架，时间根本不够用，只能尽量抽出时间记录自己学过的东西。

1.1、doubleSelect

在之前学习中，我们使用过二级列表，相信很多人都理解其原理，在struts中，同样也为我们准备了二级列表，使用doubleSelect就能够时间

**进入主题**

1、搭建环境（这里笔者使用的struts框架是2.3的）

![1015653-20161205231129726-1264275288.png][]

2、配置struts2.3环境

2.1、web.xml配置过滤器

![复制代码][copycode.gif]

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
      <display-name>LearStruts2_4</display-name>
      <welcome-file-list>
        <welcome-file>default.jsp</welcome-file>
      </welcome-file-list>
      <filter>
          <filter-name>struts2</filter-name>
          <filter-class>
            org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
          </filter-class>
      </filter>
      <filter-mapping>
          <filter-name>struts2</filter-name>
          <url-pattern>/*</url-pattern>
      </filter-mapping>
    </web-app>

![复制代码][copycode.gif]

2.2、在WEB-INF中新建class文件夹，文件夹下新建struts.xml配置信息

![复制代码][copycode.gif]

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE struts PUBLIC
        "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
        "http://struts.apache.org/dtds/struts-2.3.dtd">
    <struts>
    
        <constant name="struts.enable.DynamicMethodInvocation" value="true" />
        <constant name="struts.devMode" value="true" />
        <package name="default" namespace="/" extends="struts-default">
               <action name="doubleselectTag" class="com.struts.ui.action.DoubleSelectTagAction">
                   <result name="success">/doubleSelectTag.jsp</result>
               </action>
        </package>
    
    </struts>

![复制代码][copycode.gif]

3、新建实体类

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][]

package com.struts.ui.action;
    
    public class City {
        private int id;
         
        private String name;
         
         public City(){
         }
         
         public City(int id,String name){
          this.id = id;
          this.name = name;
         }
        public int getId() {
          return id;
         }
        public void setId(int id) {
          this.id = id;
         }
        public String getName() {
          return name;
         }
        public void setName(String name) {
          this.name = name;
         }
    }

City

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][]

package com.struts.ui.action;
    
    public class Provice {
        private int id;
         
         private String name;
         
         public Provice(){
          
         }
         
         public Provice(int id,String name){
          this.id = id;
          this.name = name;
         }
        public int getId() {
          return id;
         }
        public void setId(int id) {
          this.id = id;
         }
        public String getName() {
          return name;
         }
        public void setName(String name) {
          this.name = name;
         }
         
    }

Provice

4、新建DoubleSelectTagAction类继承ActionSupport

![复制代码][copycode.gif]

package com.struts.ui.action;
    
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import org.apache.struts2.ServletActionContext;
    
    import com.opensymphony.xwork2.ActionSupport;
    import com.opensymphony.xwork2.util.ValueStack;
    
    
    /**
     * 使用doubleSelect 二级联下拉，配置环境是struts2.3 tomcat8.0
     * 相关的类有：
     * City.java
     * Provice.java
     * doubleSelectTag.jsp
     * DoubleSelectTagAction.java
     * 访问：http://localhost:8080/LearStruts2_4/doubleselectTag
     * 目的：简单就是选择一级列表之后出现二级菜单选项
     * 这里使用的是传递对象的id到jsp页面，之后通过id查找
     * */
    
    public class DoubleSelectTagAction extends ActionSupport {
        private List<Provice> provices;// Provice对象的列表
        private Map<Integer, List<City>> cityMap;// 以Provice对象为key,Provice对应的City对象的列表作为value
         
         public Map<Integer, List<City>> getCityMap() {
            return cityMap;
        }
        public DoubleSelectTagAction(){
          
          provices = new ArrayList<Provice>();
          
          Provice provice1 = new Provice(1,"四川省");
          Provice provice2 = new Provice(2,"山东省");
          Provice provice3 = new Provice(3,"湖南省");
          Provice provice4 = new Provice(4,"广东省");
          
          provices.add(provice1);
          provices.add(provice2);
          provices.add(provice3);
          provices.add(provice4);
          
          
          List<City> cities1 = new ArrayList<City>();
          List<City> cities2 = new ArrayList<City>();
          List<City> cities3 = new ArrayList<City>();
          List<City> cities4 = new ArrayList<City>();
          
          cities1.add(new City(1,"成都市"));
          cities1.add(new City(2,"绵阳市"));
          
          cities2.add(new City(1,"济南市"));
          cities2.add(new City(2,"青岛市"));
          
          cities3.add(new City(1,"长沙市"));
          cities3.add(new City(2,"郴州市"));
          
          cities4.add(new City(1,"广州市"));
          cities4.add(new City(2,"深圳市"));
          
          
          cityMap = new HashMap<Integer,List<City>>();
          cityMap.put(provice1.getId(), cities1);
          cityMap.put(provice2.getId(), cities2);
          cityMap.put(provice3.getId(), cities3);
          cityMap.put(provice4.getId(), cities4);
          
         }
        public String execute() throws Exception {
          return SUCCESS;
         }
         
         public List<Provice> getProvices(){
          return provices;
         }
    }

![复制代码][copycode.gif]

5、新建jsp视图页面显示数据

![复制代码][copycode.gif]

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <%@ taglib uri="/struts-tags" prefix="s"%>    
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
        <s:form action="doubleselectTag">
           <s:doubleselect label="请选择所在省市" name="provice" list="provices"
            listKey="id" listValue="name" doubleList="cityMap.get(top.id)" doubleListKey="id"
            doubleListValue="name" doubleName="city"
            headerValue="----请选择----" emptyOption="true" />
      </s:form>
      
    </body>
    </html>

![复制代码][copycode.gif]

注意点：此处是map集合的键是id，所以使用到cityMap.get(top.id)，下面这种是map集合为对象的时候，代码只是有点不同。

![ContractedBlock.gif][]DoubleSelectTagAction

jsp页面

![ContractedBlock.gif][]doubleSelectTag.jsp

效果如下：效果是有的，是笔者的录制软件的问题

![1015653-20161205233241647-446043464.gif][]

总结：

原理跟二级列表类似，需要注意的点是：当使用id时，必须保证listkey=id 和 doubleList= citymap.get(top.id) 中的top.id相同。代码亲测，可以使用。

[1015653-20161205231129726-1264275288.png]: /images/20220714/184697bf70bd4364953f3b27685a5aaf.png
[copycode.gif]: /images/20220714/6029b79af7964d4dbc966ae81f494845.png
[ContractedBlock.gif]: /images/20220714/6a902451143744878d40c89bd70c2110.png
[ExpandedBlockStart.gif]: /images/20220714/9d6966bef602473a934034ed11e59ee9.png
[1015653-20161205233241647-446043464.gif]: /images/20220714/617903c678dc42b893f9d36985ca86e5.png