Struts 2 Append Tag Example

In this example we will discuss about the append tag in the strust2. Append tag is actually combine two iterators into a single iterator. he append tag is a generic tag that is used to merge multiple iterators into one iterator.

Append Iterator Tag is used to append iterators to form an appended iterator through which the entries goes from one iterator to another after each respective iterator is exhausted of entries.

In this example you see how to append the following.
  • Combine three ArrayList into a single Iterator.
  • Combine three HashMap into a single Iterator.
  • Combine ArrayList and HashMap into a single Iterator.
Create action classes:
First of all let us create a simple class called ControlTagAction.java which looks like:
package com.dineshonjava.struts2.action;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.opensymphony.xwork2.ActionSupport;

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

 private static final long serialVersionUID = 1L;
 
 private List<String> myList1 = new ArrayList<String>();
 private List<String> myList2 = new ArrayList<String>();
 private List<String> myList3 = new ArrayList<String>();
 
 private Map<String,String> myMap1 = new HashMap<String,String>();
 private Map<String,String> myMap2 = new HashMap<String,String>();
 private Map<String,String> myMap3 = new HashMap<String,String>();
 
 
 public String execute() {
  myList1.add("dinesh in list 1");
  myList1.add("anamika in list 1");
  
  myList2.add("dinesh in list 2");
  myList2.add("anamika in list 2");
  
  myList3.add("dinesh in list 3");
  myList3.add("anamika in list 3");
  
  myMap1.put("map1-key1", "dinesh in map1");
  myMap1.put("map1-key2", "anamika in map1");
  
  myMap2.put("map2-key1", "dinesh in map2");
  myMap2.put("map2-key2", "anamika in map2");
  
  myMap3.put("map3-key1", "dinesh in map3");
  myMap3.put("map3-key2", "anamika in map3");
  
  return SUCCESS;
 }


 public List<String> getMyList1() {
  return myList1;
 }


 public void setMyList1(List<String> myList1) {
  this.myList1 = myList1;
 }


 public List<String> getMyList2() {
  return myList2;
 }


 public void setMyList2(List<String> myList2) {
  this.myList2 = myList2;
 }


 public List<String> getMyList3() {
  return myList3;
 }


 public void setMyList3(List<String> myList3) {
  this.myList3 = myList3;
 }


 public Map<String, String> getMyMap1() {
  return myMap1;
 }


 public void setMyMap1(Map<String, String> myMap1) {
  this.myMap1 = myMap1;
 }


 public Map<String, String> getMyMap2() {
  return myMap2;
 }


 public void setMyMap2(Map<String, String> myMap2) {
  this.myMap2 = myMap2;
 }


 public Map<String, String> getMyMap3() {
  return myMap3;
 }


 public void setMyMap3(Map<String, String> myMap3) {
  this.myMap3 = myMap3;
 }

}

Create views
Create a file called appendtag.jsp with the following contents:
<%@ taglib prefix="s" uri="/struts-tags" %>
 <html>
<head>
<title>APPEND Control Tag Struts2 | dineshonjava.com</title>
</head>
 
<body>
<h1>Struts 2 Append tag in struts2 | dineshonjava.com</h1>
 
Combine 3 ArrayList into a single iterator.
<s:append var="mycombinelists">
     <s:param value="%{myList1}" />
     <s:param value="%{myList2}" />
     <s:param value="%{myList3}" />
</s:append>
<ol>
<s:iterator value="%{#mycombinelists}">
     <li><s:property /></li>
</s:iterator>
</ol>
 
 Combine 3 HashMap into a single iterator.
<s:append var="mycombinemaps">
     <s:param value="%{myMap1}" />
     <s:param value="%{myMap2}" />
     <s:param value="%{myMap3}" />
</s:append>
<ol>
<s:iterator value="%{#mycombinemaps}">
     <li><s:property /></li>
</s:iterator>
</ol>
 
Combine ArrayList and HashMap into a single iterator.
<s:append var="mycombinelistmap">
     <s:param value="%{myList1}" />
     <s:param value="%{myMap2}" />
</s:append>
<ol>
<s:iterator value="%{#mycombinelistmap}">
     <li><s:property /></li>
</s:iterator>
</ol>
 
</body>
</html>
The append tag takes two or more lists as parameters.

Configuration Files
Your struts.xml should look like:
<?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="appendtag" class="com.dineshonjava.struts2.action.ControlTagAction">
            <result name="success">/appendtag.jsp</result>
        </action>
        
    </package>
 </struts>
Your web.xml should look like:
<?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/appendtag

This will give you following screen:



Download Source Code
Struts2Append_Tag.zip


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