Struts 2 Tutorial Series: Sample Application – Login Module

Under Category: Struts 2

Welcome to Struts 2 Tutorial series where we will explore how to create a Struts 2 application. In this tutorial, we will first make a very simple Login application, then we expand our application to use Hibernate and Tiles, Ajax, Interceptor, Validator, etc. Finally, there will be a fully functional Struts 2 application – Quick Memo.

Goal of this sample app

We will do a simple Login module in this tutorial, since this is common for all applications. We are going to get the basic knowledge about the framework.

Finally, the login app should like this.

When Login successfully,

When Login fails,

Tools and Libraries we Need
Before we start our example, we need several tools. I’m listing what I’m using. Of course, you can use higher version, but that may caused some problems. If you just start to learn Struts 2, you can save a lot of time by using the following versions. I provide the links for your download.
1. JDK 1.5 or above
2. Tomcat 6.0
3. Eclipse IDE for Java EE Developers
4. Struts 2.0.14 (link). JAR files required for this application. Download Link.

commons-logging-1.0.4.jar
freemarker-2.3.8.jar
ognl-2.6.11.jar
struts2-core-2.0.12.jar
xwork-2.0.6.jar

Getting Started
Create a Dynamic Web Project.

#notice my project directory is: C:\eclipseworkspace\Struts2Login
Copy the required JAR files to WebContent->WEB-INF->lib folder under project directory. Now, you project should like this.

Config web.xml file

Set Struts2 as filter in web.xml file. If you don’t understand why set it as a filter, check out here.

web.xml

<?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"
	id="WebApp_ID" version="2.5">
	<display-name>Struts2 Login</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>Login.jsp</welcome-file>
	</welcome-file-list>
</web-app>

Create Login Action Class

Note that, the above action class contains two fields, username and password. They will hold values passed from form, and also contains an authenticate() method that will authenticate users. Normally, this can be setup with LDAP or Database. But here for a simple demonstration, we are simply check if username is “admin” and password is “admin”. The authenticate() method returns a string which determines the result page.

LoginAction.java

package com.programcreek.struts2;
 
import com.opensymphony.xwork2.ActionSupport;
 
public class LoginAction extends ActionSupport{
	private String username;
	private String password;
 
	public String authenticate() {
 
		if (this.username.equals("admin")
				&& this.password.equals("admin")) {
			return "success";
		} else {
			addActionError(getText("error.login"));
                        //a function from ActionSupport, to get properties values from properties file
                        //we will explore this below.
			return "error";
		}
	}
 
	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;
	}
}

Create ResourceBundle

ResourceBundle is a very useful Java entity that helps separating static contents from source code. It can hold some static messages such as names for form elements. We define an ApplicationResources.properties file for our application. This file should be present in WEB-INF/classes folder.

Now we create a source folder called resources like this.

ApplicationResources.properties

label.username= Username
label.password= Password
label.login= Login
error.login= Invalid Username/Password. Please try again.

JSP Pages
Login.jsp

<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
<title>Struts 2 - Login Application</title>
</head>
<body>
<h2>Struts 2 - Login Application</h2>
<s:actionerror />
<s:form action="login.action" method="post">
	<s:textfield name="username" key="label.username" size="20" />
	<s:password name="password" key="label.password" size="20" />
	<s:submit method="execute" key="label.login" align="center" />
</s:form>
</body>
</html>

Welcome.jsp

<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<html>
 
<head>
<title>Welcome Page - Struts 2 - Login Application</title>
</head>
 
<body>
	<h2>Congratulations, <s:property value="username" />!</h2>
	Welcome to Struts 2 world.
</body>
</html>

struts.xml file

Create struts.xml file under resources directory like the ApplicationResources.properties file.

struts.xml

<?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="ApplicationResources" />
 
	<package name="default" extends="struts-default" namespace="/">
 
		<action name="login" method="authenticate"
			class="com.programcreek.struts2.LoginAction">
			<result name="success">Welcome.jsp</result>
			<result name="error">Login.jsp</result>
 
		</action>
	</package>
</struts>

We are done

Run the project now.

Next Step
Once a user is authenticated, the website content will displayed. Normally, the content will from database. Our next step is to make a simple database usage app with Hibernate.

I will make apps based on requirements. Database is the next most important thing to understand, so I make it next step.

References:
Freemarker

Struts 2 Tutorial Series: Sample Application – Login Module

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