In the current example, 3 lists being merged, each list have 3 entries, the following will be the logic.
- Display first element of the first list.
- Display first element of the second list.
- Display first element of the third list.
- Display second element of the first list.
- Display second element of the second list.
- Display second element of the third list.
- Display third element of the first list.
- Display third element of the second list
- Display third element of the third list…..and so on..
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.List; 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>(); public String execute() { myList1.add("dinesh in list 1"); myList1.add("aadesh in list 1"); myList1.add("vinesh in list 1"); myList2.add("dinesh in list 2"); myList2.add("aadesh in list 2"); myList1.add("vinesh in list 2"); myList3.add("dinesh in list 3"); myList3.add("aadesh in list 3"); myList1.add("vinesh in list 3"); 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; } }
Create views
Create a file called merge.jsp with the following contents:
<%@ taglib prefix="s" uri="/struts-tags" %> <html> <head> <title>Merge Control Tag Struts2 | dineshonjava.com</title> </head> <body> <h1><span style="background-color: #FFFFcc">Merge Tag Example! | dineshonjava.com </span></h1> <s:merge id="mergeId"> <s:param value="%{myList1}" /> <s:param value="%{myList2}" /> <s:param value="%{myList3}" /> </s:merge> <s:iterator value="%{#mergeId}"> <s:property /><br> </s:iterator> </body> </html>
The merge 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="mergetag" class="com.dineshonjava.struts2.action.ControlTagAction"> <result name="success">/merge.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/mergetag.
This will give you following screen:
Download Source Code
Struts2AppendTag.zip