struts2杂记——使用doubleSelect

Posted 2020-08-22 书升

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了struts2杂记——使用doubleSelect相关的知识，希望对你有一定的参考价值。

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，传送门）

2、配置struts2.3环境

　2.1、web.xml配置过滤器

<?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>

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

<?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>

3、新建实体类

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

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

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;
     }
}

5、新建jsp视图页面显示数据

<%@ 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>
  <!--
      需要注意的点：
        1、list 是doubleSelectTagAction中第一个泛型集合的名称
        2、listKey 是City类的属性id    
        3、listValue 是City类的属性name
        4、doubleList  是读取map集合，top是当前list中集合的对象，注意 cityMap.get(top.id)中的id和listkey的值必须相同，cityMap是集合名称
        5、doublelistkey  是map集合对象的id
        
        如果DoubleSelectTagAction中 map集合存放的键是对象的话，那么doubleList就必须改为对象【doubleList="cities"】
   -->
</body>
</html>