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
