Struts 2 tutorial

Presented By: Prof. Vinod Pillai.

(M) 9909023599

[email protected]

http://vinodthebest.wordpress.com

mailto:[email protected]

Agenda Part – I : Understanding Struts.

Introduction.

Jakarta Struts.

Struts 2 Architecture.

Part – II : Setting Up Struts.

Getting required Packages.

“Welcome to Struts 2” – Application.

Part – III : Application Development.

10 Applications using Struts 2.

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Part – IUnderstanding

Struts3Prof. Vinod Pillai

Introduction Java Application = Desktop || Web || Mobile.

Struts = Apache Struts Web Framework.

Framework:

Peace of Software that Automates all tedioustask.

Use Design patterns commonly agreed byIndustry.

In built features that commonly needed by mostof project.

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Jakarta Struts The Apache Struts web framework is a free open-

source solution for creating Java web applications.

Apache Struts was launched in May 2000, withversion 1.0 officially released in July 2001.

Why we need it?

Web applications based on JSP sometimes combinesdatabase code, page design code, and control flow code.

In practice, we find that unless these concerns areseparated, larger applications become difficult tomaintain.

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Jakarta Struts One way to separate concerns in a software

application => Model-View-Controller (MVC)architecture.

MVC

Model = Business or database code

View = Page design code

Controller = Navigational code.

Struts framework is designed to help developerscreate web applications that utilize a MVCarchitecture.

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Model View Controller (MVC)

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Struts 2 Apache Struts Project offers two major versions:

Struts 1 is recognized as the most popular web applicationframework for Java.

Struts 2 was originally known as WebWork 2.WebWorkand Struts communities joined forces to create Struts 2.

Struts 2 is a pull-MVC framework. i.e. the data that is tobe displayed to user has to be pulled from the Action.

Action class in Struts 2 act as the model in the webapplication.

Unlike Struts, Struts 2 Action class are plain POJOobjects thus simplifying the testing of the code.

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Struts 2 Struts2 also comes with power APIs to configure

Interceptors that reduce greatly the coupling inapplication.

The view part of Struts 2 is highly configurable and itsupports different result-types such as Velocity,FreeMarker, JSP, etc.

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Struts 2 Architecture

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Struts 2 Architecture1. Request is generated by user and sent to Servlet

container.

2. Servlet container invokes FilterDispatcher filter which inturn determines appropriate action.

3. One by one Intercetors are applied before calling theAction. Interceptors performs tasks such as Logging,Validation, File Upload, Double-submit guard etc.

4. Action is executed and the Result is generated byAction.

5. The output of Action is rendered in the view (JSP,Velocity, etc) and the result is returned to the user.


Part – II

Setting Up Struts


Setting Up Struts*Before we start we need the following tools:

JDK 1.7 (Download)

Eclipse Java EE IDE for Web Developers (Indigo)

Tomcat 7 or any other container (Glassfish, JBoss,Websphere, Weblogic etc) (Download)

Apache Struts-2.0.6 JAR (Download)

MySQL Database.

MySQL Query Browser.

MySQL Java JAR File – Database connectivity.


JDK 1.7

http://www.oracle.com/technetwork/java/javase/downloads/index.html 14Prof. Vinod Pillai

Eclipse Java EE IDE

http://eclipse.org/downloads/ 15Prof. Vinod Pillai

Apache Tomcat 7

http://tomcat.apache.org/download-70.cgi 16Prof. Vinod Pillai

Apache Struts 2

http://struts.apache.org/download.cgi 17Prof. Vinod Pillai

MySQL

http://dev.mysql.com/downloads/ 18Prof. Vinod Pillai

Setting Up Struts

JDK 1.7 = .exe

Eclipse Java EE IDE = zip

Tomcat 7 = zip

Apache Struts-2.0.6 JAR = zip

MySQL Database = .exe

Simply Install the software & make sure you remember thepath.


Setting Up Struts


1“Welcome to Apache Struts 2”

Our Goal :

Our goal is to create a basic Struts2 application with a Submit Button.

User will click on the button and the page will be redirected to a Welcome page which will display message “Welcome to Apache Struts 2”.


Getting Started

Start Eclipse and enter the workspace name:


Open Eclipse and go to File -> New -> Project and selectDynamic Web Project in the New Project wizard screen.


Project Name: Welcome Struts. Target runtime: <Select New Runtime> & show the path where you have unzipped the Tomcat Server. Dynamic web module version: 2.5.


Copy JAR files in WebContent -> WEB-INF -> lib folder.


The entry point of Struts2 application will be the Filterdefine in deployment descriptor (web.xml). Hence we willdefine an entry oforg.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter class in web.xml.

Open web.xml file which is under WEB-INF folder and copypaste following code.


web.xml


The JSP

We will create two JSP files to render the output to user.

And we need index.jsp will be the starting point of our application which will contain a simple form with Button.

On clicking it will be redirected to Welcome.jsp which will display a simple welcome message.

Create three JSP files [WebContent folder ]:

index.jsp

/WEB-INF/Welcome.jsp

/WEB-INF/Error.jsp


index.jsp


Welcome.jsp

Error.jsp


struts.xml

Struts2 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 source/src folder.


The Action Class

We will need an Action class that will accept the requestand return success. For this we will create a packagecom.vinod.struts in the source folder/src. This package willcontain the action file.


Run the Application:

To run the project, right click on Project name from Project Explorer and select Run as -> Run on Server.

Note:

In Eclipse if you run the Web Application it will run inside the Eclipse inside Web Browser if you would like to change it to system installed browser then:

Select Window -> Web Browser -> Firefox.


Part – III

Application Development


2“Action & Form – Name & Last name –

Display.”Our Goal :

To create a Struts2 application with a index page. User will enter his First Name & Last Name and it will be redirected to a Welcome page which will display <First Name> & <Last Name>.


Final Structure:


index.jsp


struts.xml


Action Class


Welcome.jsp


Note: [Most Important Flow]

Request is generated by user and sent to Servlet container.

Servlet container invokes FilterDispatcher filter which in turn determines appropriate action.

One by one Intercetors are applied before calling the Action.

Action is executed and the Result is generated by Action.

The output of Action is rendered in the view (JSP, Velocity, etc) and the result is returned to the user.


3“Action Class (POJO/Plain Old Java Object)

& Form”Our Goal :

To create a Struts2 application with an index page. User willenter his First Name, Last Name and Address and it will beredirected to a Welcome page which will display <Name><Last Name> & <Address>.

Same as the above application only change is here thatAction Class is a POJO Class.

Other all same only change in Action Class.


Final Structure:


Action Class:


Note:

Here the action class doesn't extend any other class orinterface. The method invoked in the processing of an actionis the "execute" method.

How this happened?

All actions may implement this interface, which exposes theexecute() method.

You are free to create POJOs that maintains the samecontract defined by this interface without actuallyimplementing the interface.


Note:


Interceptors Interceptors are one of the most powerful features

of Struts 2.

As Interceptor, as the name suggests, intercepts therequest, and provides some additional processingbefore and after the execution of action and result.

Common functionalities required by each action areimplemented as Interceptors.

These functionalities may include validation ofinput data, pre-processing of file upload, andsometimes pre-processing of controls with somedata before the web page appears, etc.


Interceptors The interceptor approach helps in modularizing

common code into reusable classes.

The framework provides a set of Interceptors, whichcan be used to provide the required functionalitiesto an action.

User can create his custom interceptors, to get thefunctionality required for each action.


Interceptors Observe that in the figure the Action class is

executed, then a request passes through the set ofInterceptors which provide request pre-processingwhich is required before the action is executed.

Similarly after the execution of Action class allInterceptors are executed once more to providepost-processing if any.

But this time the execution order of Interceptors isreversed.


Interceptors Creating Custom Interceptor : [Two Ways]

Implementing Interceptor Interface.

Extending AbstractInterceptor Class.

Configuring Interceptors:


4“Interceptors”

Our Goal :

To create a Struts2 application with an index page. Userclicks the submit button before passing the request toAction it will be send to Interceptor then it will go to Actionand finally before showing the result it will send toInterceptor and then to Welcome.jsp/result.


Final Structure:


Interceptor Class:


Struts.xml:


Output:


Note:

With most web applications, we find ourselves wanting toapply the same set of Interceptors over and over again.Rather than reiterate the same list of Interceptors, we canbundle these Interceptors together using an InterceptorStack.


5“Common Action Class – Multiple Execute

Method ”Our Goal :

To create a Struts2 application with an index page. When theuser clicks the Update or Insert Button both goes to sameAction Class but different execute for each button.


Final Structure:


Index.jsp:


Struts.xml:


Action Class :


Insert.jsp:


Update.jsp:


Output:


6“Validation – Using validate () Method & XML”

Our Goal :

To create a Struts2 application with an index page. If userclicks the Login Button without entering the Username orPassword then it should display message appropriately errormessage.


Final Structure:


Index.jsp:


Struts.xml:


Action Class:


Welcome.jsp:


Second Option : XML File Validation


Final Structure:


LoginAction-validation.xml :


Action Class :


7“User Form”

Our Goal :

To create a Struts2 application with an index page. If userclicks the Login Button it will redirect him to Welcome pagewhere some field values are coming from Action Classvariable & some major Form Fields.


Action Class :


Welcome.jsp:


8“Integrating Tiles Plug-in”

Our Goal :

To create a Struts2 application with an index page. As userclicks the Login Button it will redirect him to Welcome pagewhich having a common design layout which will becommon for all the pages.


Final Structure:


Index.jsp:


Struts.xml:


tiles.xml:


MainLayout.jsp:


Header.jsp:

Menu.jsp:


FirstPage.jsp:

SecondPage.jsp:


8 & 9“HttpServletRequest, HttpServletResponse, ServletContext

& HttpSession”Our Goal :

Getting ServletContext Object.

Getting HttpServletRequest Object.

Getting HttpServletResponse Object.

Getting HttpSession Object.


ApplicationAware/ServletContext:


SessionAware/HttpSession:


ServletRequestAware/HttpServletRequest:


ServletResponseAware :


10“Database – Insert + Validation + View + Update”

Our Goal :

To create a Struts2 Final application in we will provide usertwo options:

First : Allow to create a New Account and the data willentered to Database.

Second : Allow user to login into the system and view hisdetails + Update his details.

Major features:

Database connectivity.

HttpServletRequest.

Session.93Prof. Vinod Pillai

Database Output:


Final Structure :


Index.jsp :


Struts.xml :


Login Action :


UserClass.java / POJO /Bean:


EditUser.jsp :


UpdateUserAction.java :


Conclusion:


What is Framework? & MVC.

Struts Architecture.

Setting Up Struts.

Welcome Struts 2 – Application.

Action – POJO.

Multiple Execute method in Action Class.

Major Form Fields.

Validation using validate() & .xml File.

Tiles Plug-in.

Request & Session Object.

Database.

Real Struts 2 Architecture


Thank You

[email protected]


Struts 2 tutorial

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Transcript of Struts 2 tutorial