Why my attempt to apply tdd failed?

Intent of my Blog

The intent of this blog is to write down the reasons for my failure to apply test driven development in my current project. Uncle Bob Martin in his interview on infoq said that “Developer is not professional if he does not practice test driven development”. We tried following tdd but failed (are we not professionals 😦 )!!

Brief Background

We had a major release few months back and till that time we were not following Test Driven Development so when the talks for the subsequent releases started we thought that we should follow tdd.I was given the responsibility to come up with strategy on how we will be applying tdd in our project. So i started with reading kent beck book Test Driven Development: By Example. I also read lots of articles  on infoq and testdriven.com to get a good and thorough understanding of tdd and was convinced that we should apply “TDD”.I gave a presentation-cum-coding demo to my team and after my demo we all were convinced that we will be applying TDD.

Ist Iteration using TDD :-Whenever you start some new thing you are excited, the same was the case with us.So before writing any class or any piece of code we used to write a test for the same. We were developing our code in an incremental manner, letting the design evolve as tdd gurus says and we were seeing small benefits like fixing programming errors like NullPointerException were caught in the early stages before the code goes to the QA team for testing.
For the next two weeks i was on leave and when i came Iteration 2 had started and tdd was no where…. So what went wrong………………

I asked my team why now we are not using tdd and the answer was that client changed the contract of one the web service that we published in iteration 1 although we had taken the feedback from him on the previous contract but somehow later he felt that this was not correct and we have to re-implement the web service with new contract and because of pressure of time we commented out all the tests and wrote the code without tests.

I started thinking about our failure to apply tdd because i think time pressure is not the only reason why teams fail to apply tdd there are many reasons. So i am writing down some reasons(in no particular order) which i think led to us not apply tdd:-

  1. Time:- Developers think that writing test cases before writing code requires more time and most often under pressure circumstances time is more important than writing test cases.
  2. Boring to write test cases first:– Its very difficult to get into the habit of writing test first than code so developers are reluctant to write test first.
  3. Client Support:- When we told our client that we will be applying tdd in our code, the response was that tdd doesn’t provide better results and in a longer run developers don’t maintain the test and they become irrelevant after some iteration.Client cares about money not test cases.
  4. Writing Exhaustive test cases :- I think tdd will make sense when you are able to cover most of the scenarios in your test class. More often what happens is that developers just write the basic test and test class doesnt evolve to incorporate all the test cases as a result developer thinks that when the number of bugs getting raised is not decreasing why should i write test.
  5. Patience :- I think it is very important that we should not expect everything to go fine and everyone to become tdd guru in one iteration. So we should give tdd few iterations before we can judge whether its useful or not.
  6. Poor Examples :- The example with which tdd is often taught are very simple as compared to the one you face in real life scenarios.So it becomes difficult to follow tdd when there is some real complex problem come.
  7. Legacy Code

In short, i can say that applying tdd requires a complete change in mindset you have start fresh.These are some of the reasons that i could think of at this point of time why applying tdd failed.
Please share your views also.

Creating Struts2 application on Google App Engine (GAE)

Why i am writing this blog?

I faced lot of problems while creating my first application using Struts 2 on Google App Engine . So i decided to write a blog detailing how developers can create their application on Struts2 by avoiding the problems that i faced while developing my application.

Note

If you want to do FileUpload using struts 2  on google app engine please refer to this post.

Prerequisites for starting Struts2 Application on Google App Engine

Before you start building your sample application on google app engine using struts 2 you will need the following:-

  1. Google App Engine runs on java 5 and above so if necessary, download and install the Java SE Development Kit (JDK) for your platform and for mac users download and install the latest version.
  2. In this example we will be using Eclipse as our ide. So if necessary, download eclipse and google app engine plugin for eclipse.You will also need to download the google  java app engine SDK. For more information you can refer to installing the java SDK for google app engine.
  3. Download the latest release of Struts2 framework.If you want to learn struts 2 a very good reference is struts 2 in action book.Please buy Struts 2 in Action.

Step by Step procedure to create Struts2 application on Google App Engine.

Step 1: Create a new project by clicking the New Web Application Project button in the toolbarnew_app_button.

1

Step 2 : Give the project name say login  as we are going to create a simple login application. Enter package name as com.login and uncheck “Use Google Web Toolkit,” and ensure “Use Google App Engine” is checked and click the finish button.

2

Step3 : When you click the finish button you will get a sample HelloWorld application, which you can run going in the Run menu, select Run As > Web Application.By default application will run at port 8080, you can view the sample application at http://locahost:8080. For more information on the sample google web application created by the plugin you can refer to Google java app engine documentation .Please keep in mind that intent of this document is not to provide developers the overview of Google App engine for Java.

Step4 : By now you are ready with the google app engine infrastructure and we can move to the next step of creating a login application in Struts 2.

  • for creating a struts 2 application you will need to first add the required dependencies to the login project. The required struts 2 jars are below mentioned and you can find these jars in struts2 package you downloaded inside the lib folder :-
    • commons-fileupload-1.2.1.jar
    • commons-io-1.3.2.jar
    • commons-logging-1.1.jar
    • freemarker-2.3.13.jar
    • ognl-2.6.11.jar
    • struts2-core-2.1.6.jar
    • xwork-2.1.2.jar
  • Add these dependencies in your eclipse java build path.

3

  • Add these dependencies in the war/WEB-INF/lib folder so that these jars gets deployed along with your application.

4

  • As you can see in the above image there are some warnings in the problems view like  “commons-fileupload-1.2.1.jar’ will not be available on the server’s classpath” .To remove these warnings you need to right click on the project and select properties and then go to Google > web application and click the add button and add all the jars and then press ok.

5

  • First step in creating a struts 2 application is configuring the web.xml (deployment descriptor) which is located in WEB-INF folder.You can remove the servlet declaration from web.xml as we will not be needing this.We need to add the FilterDispatcher declaration in web.xml because in struts2 every request goes  pass through FilterDispatcher which will invoke the appropriate action corresponding to the URL mapping.So our web.xml will 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_2_5.xsd"
	version="2.5">
	<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.html</welcome-file>
	</welcome-file-list>
</web-app>
  • To start we will be creating a jsp login page using struts 2 tag library and we will call login page from index.html.To call the login page there are two ways first, we can directly call the login.jsp page from link second, we can calling it through struts. We will be taking the second step as this will show you how to configure actions when you dont need to invoke any action.Lets first see how our login page and index.html will look like :-

index.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Struts2 on Google App Engine</title>
</head>

<body>
<h1>Struts2 on Google App Engine!</h1>
<table>
<tr>
<td colspan="2" style="font-weight: bold;">Available Application:</td>
</tr>
<tr>
<td><a href="/member/login" />Login</td>
</tr>
</table>
</body>
</html>

login.jsp

<%@ 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>Please login</title>
</head>
<body>
 <s:actionerror/>
 <s:form action="home" method="post">
 <s:textfield name="username" label="UserName"></s:textfield>
 <s:textfield name="password" label="Password"></s:textfield>
 <s:submit name="login" value="login"></s:submit>
 </s:form>
</body>
</html>
  • After creating the login.jsp we need to configure this as action in the struts.xml file which you be should put inside source folder parallel to log4j.properties file.We can configure action as mentioned below:-
<?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>
	<include file="struts-default.xml"></include>
<package name="member" namespace="/member" extends="struts-default">
		<action name="login">
			<result>/login.jsp</result>
		</action>
	</package>
</struts>
  • Now try running this application by right click on project run as > web application and click http://localhost:8080. You will see index.html and when you click on login you will get this exception :-

SEVERE: Unable to set parameter [location] in result of type    [org.apache.struts2.dispatcher.ServletDispatcherResult]

Caught OgnlException while setting property ‘location’ on type ‘org.apache.struts2.dispatcher.ServletDispatcherResult’. – Class: ognl.OgnlRuntime

File: OgnlRuntime.java

Method: invokeMethod

Line: 508 – ognl/OgnlRuntime.java:508:-1

at com.opensymphony.xwork2.ognl.OgnlUtil.internalSetProperty(OgnlUtil.java:392)

Caused by: java.lang.IllegalAccessException: Method [public void org.apache.struts2.dispatcher.StrutsResultSupport.setLocation(java.lang.String)] cannot be accessed.

at ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:508)

at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:812)

at ognl.OgnlRuntime.setMethodValue(OgnlRuntime.java:964)

at ognl.ObjectPropertyAccessor.setPossibleProperty(ObjectPropertyAccessor.java:75)

at ognl.ObjectPropertyAccessor.setProperty(ObjectPropertyAccessor.java:131)

at com.opensymphony.xwork2.ognl.accessor.ObjectAccessor.setProperty(ObjectAccessor.java:28)

at ognl.OgnlRuntime.setProperty(OgnlRuntime.java:1656)

at ognl.ASTProperty.setValueBody(ASTProperty.java:101)

at ognl.SimpleNode.evaluateSetValueBody(SimpleNode.java:177)

at ognl.SimpleNode.setValue(SimpleNode.java:246)

at ognl.Ognl.setValue(Ognl.java:476)

at com.opensymphony.xwork2.ognl.OgnlUtil.setValue(OgnlUtil.java:192)

at com.opensymphony.xwork2.ognl.OgnlUtil.internalSetProperty(OgnlUtil.java:385)

… 73 more

  • In order to resolve this problem we  need to create an ServletContextListner which will set OGNL security manager to null when the context is initialized.
package com.login;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import ognl.OgnlRuntime;

public class OgnlListener implements ServletContextListener {

	@Override
	public void contextDestroyed(ServletContextEvent arg0) {
		// TODO Auto-generated method stub

	}

	@Override
	public void contextInitialized(ServletContextEvent arg0) {
		OgnlRuntime.setSecurityManager(null);
	}

}
  • Also we will need to make entry in web.xml file also for OgnlListener
	<listener>
	<listener-class>com.login.OgnlListener</listener-class>
</listener>
  • Now if you run the web application you will see the login page.
  • You need to add this step if you are using Google App Engine 1.2.6 because when you run struts2 application on google app engine 1.2.6 you will get the following error:-

javax.servlet.ServletException: java.lang.NoClassDefFoundError: javax.swing.tree.TreeNode is a restricted class. Please see the Google App Engine developer’s guide for more details.
at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:825)
at org.apache.jasper.runtime.PageContextImpl.access$1100(PageContextImpl.java:64)
at org.apache.jasper.runtime.PageContextImpl$12.run(PageContextImpl.java:745)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:743)
at org.apache.jsp.login_jsp._jspService(login_jsp.java:86)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
at com.google.appengine.tools.development.PrivilegedJspServlet.access$101(PrivilegedJspServlet.java:23)
at com.google.appengine.tools.development.PrivilegedJspServlet$2.run(PrivilegedJspServlet.java:59)
at java.security.AccessController.doPrivileged(Native Method)
at com.google.appengine.tools.development.PrivilegedJspServlet.service(PrivilegedJspServlet.java)

To avoid this error you need to create a new package “freemarker.core” in your source folder and add the following class

</span></span>

/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above
copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software
itself,
 *    if and wherever such third-party acknowledgements normally
appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names
of the
 *    project contributors may be used to endorse or promote products
derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigo...@visigoths.org.
 *
 * 5. Products derived from this software may not be called
"FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software
Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.core;

import java.io.IOException;

/**
 * A TemplateElement representing a block of plain text.
 *
 * @version $Id: TextBlock.java,v 1.17 2004/01/06 17:06:42 szegedia Exp $
 */
public final class TextBlock extends TemplateElement {
 private static final char[] EMPTY_CHAR_ARRAY = new char[0];
 static final TextBlock EMPTY_BLOCK = new TextBlock(EMPTY_CHAR_ARRAY, false);
 // We're using char[] instead of String for storing the text block because
 // Writer.write(String) involves copying the String contents to a char[]
 // using String.getChars(), and then calling Writer.write(char[]).By
 // using Writer.write(char[]) directly, we avoid array copying on each
 // write.
 private char[] text;
 private final boolean unparsed;

 public TextBlock(String text) {
 this(text, false);
 }

 public TextBlock(String text, boolean unparsed) {
 this(text.toCharArray(), unparsed);
 }

 private TextBlock(char[] text, boolean unparsed) {
 this.text = text;
 this.unparsed = unparsed;
 }

 /**
 * Simply outputs the text.
 */
 public void accept(Environment env) throws IOException {
 env.getOut().write(text);
 }

 public String getCanonicalForm() {
 String text = new String(this.text);
 if (unparsed) {
 return "<#noparse>" + text + "</#noparse>";
 }
 return text;
 }

 public String getDescription() {
 String s = new String(text).trim();
 if (s.length() == 0) {
 return "whitespace";
 }
 if (s.length() > 20) {
 s = s.substring(0, 20) + "...";
 s = s.replace('\n', ' ');
 s = s.replace('\r', ' ');
 }
 return "text block (" + s + ")";
 }

 TemplateElement postParseCleanup(boolean stripWhitespace) {
 if (text.length == 0)
 return this;
 int openingCharsToStrip = 0, trailingCharsToStrip = 0;
 boolean deliberateLeftTrim = deliberateLeftTrim();
 boolean deliberateRightTrim = deliberateRightTrim();
 if (!stripWhitespace || text.length == 0) {
 return this;
 }
 if (parent.parent == null && previousSibling() == null)
 return this;
 if (!deliberateLeftTrim) {
 trailingCharsToStrip = trailingCharsToStrip();
 }
 if (!deliberateRightTrim) {
 openingCharsToStrip = openingCharsToStrip();
 }
 if (openingCharsToStrip == 0 && trailingCharsToStrip == 0) {
 return this;
 }
 this.text = substring(text, openingCharsToStrip, text.length
 - trailingCharsToStrip);
 if (openingCharsToStrip > 0) {
 this.beginLine++;
 this.beginColumn = 1;
 }
 if (trailingCharsToStrip > 0) {
 this.endColumn = 0;
 }
 return this;
 }

 /**
 * Scans forward the nodes on the same line to see whether there is a
 * deliberate left trim in effect. Returns true if the left trim was
 * present.
 */
 private boolean deliberateLeftTrim() {
 boolean result = false;
 for (TemplateElement elem = this.nextTerminalNode(); elem != null
 && elem.beginLine == this.endLine; elem = elem
 .nextTerminalNode()) {
 if (elem instanceof TrimInstruction) {
 TrimInstruction ti = (TrimInstruction) elem;
 if (!ti.left && !ti.right) {
 result = true;
 }
 if (ti.left) {
 result = true;
 int lastNewLineIndex = lastNewLineIndex();
 if (lastNewLineIndex >= 0 || beginColumn == 1) {
 char[] firstPart = substring(text, 0,
 lastNewLineIndex + 1);
 char[] lastLine = substring(text, 1 + lastNewLineIndex);
 if (trim(lastLine).length == 0) {
 this.text = firstPart;
 this.endColumn = 0;
 } else {
 int i = 0;
 while (Character.isWhitespace(lastLine[i])) {
 i++;
 }
 char[] printablePart = substring(lastLine, i);
 this.text = concat(firstPart, printablePart);
 }
 }
 }
 }
 }
 if (result) {
 }
 return result;
 }

 /**
 * Checks for the presence of a t or rt directive on the same line. Returns
 * true if the right trim directive was present.
 */
 private boolean deliberateRightTrim() {
 boolean result = false;
 for (TemplateElement elem = this.prevTerminalNode(); elem != null
 && elem.endLine == this.beginLine; elem = elem
 .prevTerminalNode()) {
 if (elem instanceof TrimInstruction) {
 TrimInstruction ti = (TrimInstruction) elem;
 if (!ti.left && !ti.right) {
 result = true;
 }
 if (ti.right) {
 result = true;
 int firstLineIndex = firstNewLineIndex() + 1;
 if (firstLineIndex == 0) {
 return false;
 }
 if (text.length > firstLineIndex
 && text[firstLineIndex - 1] == '\r'
 && text[firstLineIndex] == '\n') {
 firstLineIndex++;
 }
 char[] trailingPart = substring(text, firstLineIndex);
 char[] openingPart = substring(text, 0, firstLineIndex);
 if (trim(openingPart).length == 0) {
 this.text = trailingPart;
 this.beginLine++;
 this.beginColumn = 1;
 } else {
 int lastNonWS = openingPart.length - 1;
 while (Character.isWhitespace(text[lastNonWS])) {
 lastNonWS--;
 }
 char[] printablePart = substring(text, 0, lastNonWS + 1);
 if (trim(trailingPart).length == 0) {
 // THIS BLOCK IS HEINOUS! THERE MUST BE A BETTER
 // WAY! REVISIT (JR)
 boolean trimTrailingPart = true;
 for (TemplateElement te = this.nextTerminalNode(); te != null
 && te.beginLine == this.endLine; te = te
 .nextTerminalNode()) {
 if (te.heedsOpeningWhitespace()) {
 trimTrailingPart = false;
 }
 if (te instanceof TrimInstruction
 && ((TrimInstruction) te).left) {
 trimTrailingPart = true;
 break;
 }
 }
 if (trimTrailingPart)
 trailingPart = EMPTY_CHAR_ARRAY;
 }
 this.text = concat(printablePart, trailingPart);
 }
 }
 }
 }
 return result;
 }

 /*
 * private String leftTrim(String s) { int i =0; while (i<s.length()) { if
 * (!Character.isWhitespace(s.charAt(i))) break; ++i; } return
 * s.substring(i); }
 */
 private int firstNewLineIndex() {
 String content = new String(text);
 int newlineIndex1 = content.indexOf('\n');
 int newlineIndex2 = content.indexOf('\r');
 int result = newlineIndex1 >= 0 ? newlineIndex1 : newlineIndex2;
 if (newlineIndex1 >= 0 && newlineIndex2 >= 0) {
 result = Math.min(newlineIndex1, newlineIndex2);
 }
 return result;
 }

 private int lastNewLineIndex() {
 String content = new String(text);
 return Math.max(content.lastIndexOf('\r'), content.lastIndexOf('\n'));
 }

 /**
 * figures out how many opening whitespace characters to strip in the
 * post-parse cleanup phase.
 */
 private int openingCharsToStrip() {
 int newlineIndex = firstNewLineIndex();
 if (newlineIndex == -1 && beginColumn != 1) {
 return 0;
 }
 ++newlineIndex;
 if (text.length > newlineIndex) {
 if (newlineIndex > 0 && text[newlineIndex - 1] == '\r'
 && text[newlineIndex] == '\n') {
 ++newlineIndex;
 }
 }
 if (new String(text).substring(0, newlineIndex).trim().length() > 0) {
 return 0;
 }
 // We look at the preceding elements on the line to see if we should
 // strip the opening newline and any whitespace preceding it.
 for (TemplateElement elem = this.prevTerminalNode(); elem != null
 && elem.endLine == this.beginLine; elem = elem
 .prevTerminalNode()) {
 if (elem.heedsOpeningWhitespace()) {
 return 0;
 }
 }
 return newlineIndex;
 }

 /**
 * figures out how many trailing whitespace characters to strip in the
 * post-parse cleanup phase.
 */
 private int trailingCharsToStrip() {
 String content = new String(text);
 int lastNewlineIndex = lastNewLineIndex();
 if (lastNewlineIndex == -1 && beginColumn != 1) {
 return 0;
 }
 String substring = content.substring(lastNewlineIndex + 1);
 if (substring.trim().length() > 0) {
 return 0;
 }
 // We look at the elements afterward on the same line to see if we
 // should strip any whitespace after the last newline
 for (TemplateElement elem = this.nextTerminalNode(); elem != null
 && elem.beginLine == this.endLine; elem = elem
 .nextTerminalNode()) {
 if (elem.heedsTrailingWhitespace()) {
 return 0;
 }
 }
 return substring.length();
 }

 boolean heedsTrailingWhitespace() {
 if (isIgnorable()) {
 return false;
 }
 for (int i = 0; i < text.length; i++) {
 char c = text[i];
 if (c == '\n' || c == '\r') {
 return false;
 }
 if (!Character.isWhitespace(c)) {
 return true;
 }
 }
 return true;
 }

 boolean heedsOpeningWhitespace() {
 if (isIgnorable()) {
 return false;
 }
 for (int i = text.length - 1; i >= 0; i--) {
 char c = text[i];
 if (c == '\n' || c == '\r') {
 return false;
 }
 if (!Character.isWhitespace(c)) {
 return true;
 }
 }
 return true;
 }

 boolean isIgnorable() {
 if (text == null || text.length == 0) {
 return true;
 }
 if (!isWhitespace()) {
 return false;
 }
 // trick here
 boolean atTopLevel = true;
 TemplateElement prevSibling = previousSibling();
 TemplateElement nextSibling = nextSibling();
 return ((prevSibling == null && atTopLevel) || nonOutputtingType(prevSibling))
 && ((nextSibling == null && atTopLevel) || nonOutputtingType(nextSibling));
 }

 private boolean nonOutputtingType(TemplateElement element) {
 return (element instanceof Macro || element instanceof Assignment
 || element instanceof AssignmentInstruction
 || element instanceof PropertySetting
 || element instanceof LibraryLoad || element instanceof Comment);
 }

 private static char[] substring(char[] c, int from, int to) {
 char[] c2 = new char[to - from];
 System.arraycopy(c, from, c2, 0, c2.length);
 return c2;
 }

 private static char[] substring(char[] c, int from) {
 return substring(c, from, c.length);
 }

 private static char[] trim(char[] c) {
 if (c.length == 0) {
 return c;
 }
 return new String(c).trim().toCharArray();
 }

 private static char[] concat(char[] c1, char[] c2) {
 char[] c = new char[c1.length + c2.length];
 System.arraycopy(c1, 0, c, 0, c1.length);
 System.arraycopy(c2, 0, c, c1.length, c2.length);
 return c;
 }

 boolean isWhitespace() {
 return text == null || trim(text).length == 0;
 }

}

  • Next step is to create the LoginAction which will be do the business processing of whether usename and password are correct .
package com.login;

import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport {

	private static final long serialVersionUID = 1L;
	private String username;
	private String password;

	public String login(){
		if(username.equals("whyjava") && password.equals("password")){
			addActionMessage("You are successfully logged in.");
			return SUCCESS;
		}
		addActionError("Username and Password Combination doesnot match.");
		return INPUT;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

}

  • Next we need to modify struts.xml so that we LoginAction is configured.
<?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>
	<include file="struts-default.xml"></include>
<package name="member" namespace="/member" extends="struts-default">
		<action name="login">
			<result>/login.jsp</result>
		</action>
		<action name="home" method="login" class="com.login.LoginAction">
			<result>/home.jsp</result>
			<result name="input">/login.jsp</result>
		</action>
	</package>
</struts>
  • finally we need to add one more jsp which is home.jsp which will be called when user is able to successfully login.
<%@ 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>Home Page</title>
</head>
<body>
<s:actionmessage />

</body>
</html>
  • Now try running this application by right click on project run as > web application and click http://localhost:8080.

index

  • Now click on the login link you will be taken to the login page

login

  • Now enter username as whyjava and password as password you will be an struts 2 action will fire and you will be taken to the home page.

home

I have tried to cover all the steps you will need to start of your first struts 2 project. Hope you all find this post useful.

If you need to start learning struts2 you can read Struts 2 in Action. It is a very good book to get a very good understanding of all the struts 2 concepts.