package com;

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

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class JstlFnAction extends Action {

 @Override
 public ActionForward execute(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response)
   throws Exception {
  
  request.setAttribute("hello", "Hello World !");
  
  List<String> list = new ArrayList<String>();
  list.add("a");
  list.add("b");
  request.setAttribute("list", list);
  
  request.setAttribute("username", "KIMURA SAORI");
  return mapping.findForward("success");
 }

}

 <?xml version="1.0" encoding="UTF-8" ?>

<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/j2eehttp://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
  version="2.0">
   
  <description>my functions library</description>
  <display-name>my functions</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>mf</short-name>
  <uri>myURI</uri>
 
  <function>
    <name>sayHello</name>
    <function-class>com.MyFunction</function-class>
    <function-signature>java.lang.String sayHello(java.lang.String)</function-signature>
  </function>

</taglib>

package com;

public class MyFunction {
 
 public static String sayHello(String name) {
  return "Hello "+name+" !";
 }
}