Tutorial: Creating Struts application in NetBeans

Things We Need

Before we starts with our first Hello World Struts  Example, we will need following Software & Resource.


Software or ResourceVersion Required
NetBeans IDE7.1, 7.2, 7.3, 7.4, Java EE
Java Development Kit (JDK)6 or 7
GlassFish server 
or 
Tomcat servlet container		Open Source Edition 3.x or 4.0 
  
version 6.x or 7.x
Notes:
  • The Java installation enables you to optionally install the GlassFish server and the Apache Tomcat servlet container. You must install one of these (or register a different server in the IDE) to work through this tutorial.
  • If you need to compare your project with a working solution, you can download the sample application.

Getting Started

Let us start with our first Struts based application.

Open  NetBeans and goto File -> New  Project and select  JAVA Web --> Web Application in the New Project wizard screen.


After selecting Web Application Project, press Next.



Write the name of the project. For example StrutsHelloWorld. Once this is done, select the target runtime environment (e.g. Apache Tomcat 7.0.34.0). This is to run the project inside NetBeans environment. After this press Next.


Select the  Struts 1.3.10 frameworks  and Select Add Struts TLDs. After this press Finish.

Once the project is created, you can see its structure in Project Explorer.



Mapping Struts in WEB.xml





The Action Class

We will need an Action class that will authenticate our user and holds the value for username and password. For this we will create a package com.myapp.struts.action in the source folder. This package will contain the action file.


Create a class called LoginAction in com.myapp.struts,action package with following content.


package com.myapp.struts.action;

public class LoginAction {

    private String username;
    private String password;

    public String execute() {

        if (this.username.equals("admin")
                && this.password.equals("admin123")) {
            return "success";
        } else {
            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;
    }
}


Note that, above action class contains two fields, username and password which will hold the values from form and also contains an execute() method that will authenticate the user. In this simple example, we are checking if username is admin and password is admin123.

Also note that unlike Action class in Struts1, Struts2 action class is a simple POJO class with required attributes and method.

The execute() method returns a String value which will determine the result page. Also, in Struts2 the name of the method is not fixed. In this example we have define method execute(). You may want to define a method authenticate() instead.

The ResourceBundle

ResourceBundle is very useful Java entity that helps in putting the static content away from the source file. Most of the application define a resource bundle file such as ApplicationResources.properties file which contains static messages such as Username or Password and include this with the application.

ResourceBundle comes handy when we want to add Internationalization (I18N) support to an application.

We will define an ApplicationResources.properties file for our application. This property file should be present in WEB-INF/classes folders when the source is compiled. Thus we will create a source folder called resources and put the ApplicationResources.properties file in it.

a file ApplicationResources.properties under com.myapp.struts folder.


Copy following content in ApplicationResources.properties.
label.username= Username
label.password= Password
label.login= Login

The JSP

We will create two JSP files to render the output to user. Login.jsp will be the starting point of our application which will contain a simple login form with username and password. On successful authentication, user will be redirected to Welcome.jsp which will display a simple welcome message.

Create two JSP files Login.jsp and Welcome.jsp in WebContent folder of your project. Copy following content into it.

Login.jsp

<%@ page contentType="text/html; charset=UTF-8"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %>
<html>
<head>
<title>Struts 2- Login Application</title>
</head>
<body>
<h2>Struts2- Login Application</h2>
<html:actionerror />
<html:form action="login.action" method="post">
    <html:textfield name="username" key="label.username" size="20" />
    <html:password name="password" key="label.password" size="20" />
    <html:submit method="execute" key="label.login" align="center" />
</html:form>
</body>
</html>

WelcomeStruts.jsp

<%@page contentType="text/html"%>
<%@page pageEncoding="UTF-8"%>

<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean" %>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %>
<%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic" %>

<html:html lang="true">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title><bean:message key="welcome.title"/></title>
        <html:base/>
    </head>
    <body style="background-color: white">

        <h2>Howdy, <html:property value="username" />...!</h2>   
        <h3><bean:message key="welcome.heading"/></h3>
        <p><bean:message key="welcome.message"/></p>

    </body>
</html:html>
Note that we have used struts <html:> tag to render the textboxes and labels. Struts  comes with a powerful built-in tag library to render UI elements more efficiently.

The struts.xml file

Struts reads the configuration and class definition from an xml file called struts.xml. This file is loaded from the classpath of the project. We will define struts.xml file in the com.myapp.struts folder. Create file struts.xml in resources folder.
Copy following content into 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"
            class="net.viralpatel.struts2.LoginAction">
            <result name="success">Welcome.jsp</result>
            <result name="error">Login.jsp</result>
        </action>
    </package>
</struts>
Note that in above configuration file, we have defined Login action of our application. Two result paths are mapped with LoginAction depending on the outcome of execute() method. If execute() method returns success, user will be redirected to WelcomeStruts.jsp else to Login.jsp.

Also note that a constant is specified with name struts.custom.i18n.resources. This constant specify the resource bundle file that we created in above steps. We just have to specify name of resource bundle file without extension (ApplicationResources without .properties).

Our LoginAction contains the method execute() which is the default method getting called by Sturts2. If the name of method is different, e.g. authenticate(); then we should specify the method name in <action> tag.

<action name="login" method="authenticate"
    class="com.myapp.struts.LoginAction">

Final Touch

To add this functionality first we will add the error message in our ResourceBundle file.

Open ApplicationResources.properties and add an entry for error.login in it. The final ApplicationResources.properties will look like:

label.username= Username
label.password= Password
label.login= Login
error.login= Invalid Username/Password. Please try again.
Also we need to add logic in LoginAction to add error message if user is not authenticated. But there is one problem. Our error message is specified in ApplicationResources.properties file. We must specify key error.login in LoginAction and the message should be displayed on JSP page.

For this we must implement com.opensymphony.xwork2.TextProvider interface which provides method getText(). This method returns String value from resource bundle file. We just have to pass the key value as argument to getText() method. The TextProvider interface defines several method that we must implement in order to get hold on getText() method. But we don’t want to spoil our code by adding all those methods which we do not intend to use. There is a good way of dealing with this problem.

Struts2 comes with a very useful class com.opensymphony.xwork2.ActionSupport. We just have to extend our LoginAction class with this class and directly use methods such as getText(), addActionErrors() etc. Thus we will extend the LoginAction class with ActionSupport class and add the logic for error reporting into it. The final code in LoginAction must look like:

package com.myapp.struts.action;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction extends ActionSupport {
    private String username;
    private String password;
    public String execute() {
        if (this.username.equals("admin")
                && this.password.equals("admin123")) {
            return "success";
        } else {
            addActionError(getText("error.login"));
            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;
    }
}

That’s All Folks

Execute the application in NetBeans and run it in your favorite browser.
Login page
 
 

Welcome page
 

Login page with error

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