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Struts2

Struts2 subset Tag Example

The subset tag is a generic tag is used to output a subset or portion of an iterator elements. The following Example will shows how to implement the subset tag in the Struts2.

First we create a JSP file named subsettag.jsp as follows.

Now create a jsp page using <s:subset> and <s:iterator> tags as shown in the SubsetTag.jsp page. The subset tag takes an iterator and outputs a subset of it. The parameter count is of integer type and it sets the number of entries to be kept in the resulting subset iterator.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
 <%@ taglib prefix="s" uri="/struts-tags"%>
<!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=ISO-8859-1">
 <title>Subset Control Tag Struts2 | dineshonjava.com</title> 
</head>
<body>
 <h1><span style="background-color: #FFFFcc">Subset Tag Example! | dineshonjava.com
  </span></h1>
 <b>The Subset of first 2 values :</b>
 <s:subset source="userList" count="2">
  <ol> 
   <s:iterator>
    <li>
     <s:property value="userId" /> ,
     <s:property value="userName" /> ,
     <s:property value="age" />
    </li>
   </s:iterator>
  </ol><br>
 </s:subset>
<b>The Subset of 2 values starting from 3rd index :</b>
 <s:subset source="userList" start="2" count="2">
  <ol> 
   <s:iterator>
    <li>
     <s:property value="userId" /> ,
     <s:property value="userName" /> ,
     <s:property value="age" />
    </li>
   </s:iterator>
  </ol><br>
 </s:subset>
 </body>
</html>

The Struts mapping file Struts.xml is as follows-

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
 
<struts>
    <constant name="struts.enable.DynamicMethodInvocation" value="false" />
    <constant name="struts.devMode" value="false" />
    <constant name="struts.custom.i18n.resources" value="myapp" />
 
    <package name="default" extends="struts-default" namespace="/">
        <action name="subsettag" class="com.dineshonjava.struts2.action.ControlTagAction">
            <result name="success">/subsettag.jsp</result>
        </action>
        
    </package>
 </struts>

Create action class:

The action class ControlTagAction.java is as follows.

package com.dineshonjava.struts2.action;

import java.util.ArrayList;
import java.util.List;

import com.dineshonjava.struts2.domain.User;
import com.opensymphony.xwork2.ActionSupport;

/**
 * @author Dinesh Rajput
 *
 */
public class ControlTagAction extends ActionSupport{

 private static final long serialVersionUID = 1L;
 
 private List<User> userList = new ArrayList<User>();
 
 public String execute() {
  
  User user1 = new User();
  user1.setAge(27);
  user1.setUserId(111);
  user1.setUserName("Dinesh Rajput");
  
  User user2 = new User();
  user2.setAge(25);
  user2.setUserId(222);
  user2.setUserName("Anamika Rajput");
  
  User user3 = new User();
  user3.setAge(23);
  user3.setUserId(333);
  user3.setUserName("Aadesh");
  
  User user4 = new User();
  user4.setAge(21);
  user4.setUserId(444);
  user4.setUserName("Vinesh Rajput");
  
  userList.add(user1);
  userList.add(user2);
  userList.add(user3);
  userList.add(user4);
  
  return SUCCESS;
 }

 public List<User> getUserList() {
  return userList;
 }


 public void setUserList(List<User> userList) {
  this.userList = userList;
 }
}

Create web.xml file as below.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Struts2ControlTags</display-name>
  <filter>
        <filter-name>struts2</filter-name>
        <filter-class>
            org.apache.struts2.dispatcher.FilterDispatcher
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

Right click on the project name and click Export > WAR File to create a War file. Then deploy this WAR in the Tomcat’s webapps directory. Finally, start Tomcat server and try to access

URL http://localhost:8080/doj/subsettag.

This will give you following screen:

Download Source Code
Struts2SUbsetTag.zip

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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!