Struts 2 - Introduction

Java Hibernate Training
Introducing Struts Framework

Classification: Restricted
Agenda
• Introduction to Struts Framework
• Features
• Evolution
• Struts Demo
• Declarative validation
• Architecture
• Validators
• Interceptors

Struts framework
• The struts 2 framework is used to develop MVC-based
web application.
• The struts framework was initially created by Craig
McClanahan and donated to Apache Foundation in May,
2000 and Struts 1.0 was released in June 2001.
• Craig R. McClanahan is a programmer and original
author of the Apache Struts framework for building web
applications. He was part of the expert group that
defined the servlet 2.2, 2.3 and JSP 1.1, 1.2
specifications. He is also the architect of Tomcat's servlet
container Catalina.

Struts 2 Framework
• The Struts 2 framework is used to develop MVC (Model View Controller)
based web applications. Struts 2 is the combination of webwork
framework of opensymphony and struts 1.
struts2 = webwork + struts1

Struts 2 Features
• Configurable MVC components
• POJO based actions
• AJAX support
• Integration support – with Hibernate, Spring etc
• Various Result Types – JSP, Freemarker, Velocity etc
• Various Tag support
• Theme and Template support

Web Application Architecture - Evolution
• Model 1 Architecture
pag
e 5
• Navigation control is decentralized
• Time Consuming
• Hard to extend

Web Application Architecture - Evolution
• Model 2 Architecture
pag
e 6
• Navigation control is centralized Now only controller contains the logic to determine the next
page.
• Easy to maintain, extend and test
• Better separation of concerns
• (SOLID principles: OOP: Single Responsibility Principle)

Struts… building your first app
• Struts – Configuring in Eclipse demo

• JSP: Server Page technology… like ASP, BSP…
• Page is dynamically built on the server…
• Presentation logic goes into the server.
• Limitation:
• As number of clients increases, the server has more work to do. (Controller
logic + Presentation Logic)
• If your web app is responsive/adaptive, it has much more work to do on the
presentation logic.. It has to check the form factor of the device that is
trying to access the web page…
• Solution:
• Move the presentation logic to the client… JS libraries (Angular) + CSS (LESS,
SASS)..
• RESTful architecture.

Struts demo
• Login Page
• Validation Example

Declarative validation
//<ActionClassName>-validation.xml
<?xml version="1.0" encoding="UTF-8"?>
Use appropriate DTD here!!
<!DOCTYPE validators PUBLIC
"-//OpenSymphony Group//XWork Validator 1.0.2//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
<validators>
<field name="username">
<field-validator type="requiredstring">
<message>Name can't be blank</message>
</field-validator>
</field>

Struts 2 Architecture

Struts ready-to-use Validators
• requiredstring validator
• stringlength validator
• email validator
• date validator
• int validator
• double validator
• url validator
• regex validator

Struts 2 interceptors
• Interceptors are conceptually the same as servlet filters or the JDKs Proxy
class. Interceptors allow for crosscutting functionality to be implemented
separately from the action as well as the framework. You can achieve the
following using interceptors:
• Providing preprocessing logic before the action is called.
• Providing postprocessing logic after the action is called.
• Catching exceptions so that alternate processing can be performed.

17-08-2018 14
Interceptors
 Can execute code before and after execution
 Are thread-safe
 Can be used for
 Validation
 Pre populating fields
 Double-submit prevention
 Session control
 Authentication
 Type conversion

Some Struts 2 Interceptors
alias Allows parameters to have different name aliases across requests.
checkbox Assists in managing check boxes by adding a parameter value of
false for check boxes that are not checked.
conversionError Places error information from converting strings to parameter
types into the action's field errors.
createSession Automatically creates an HTTP session if one does not already
exist.
debugging Provides several different debugging screens to the developer.
execAndWait Sends the user to an intermediary waiting page while the action
executes in the background.
exception Maps exceptions that are thrown from an action to a result,
allowing automatic exception handling via redirection.
fileUpload Facilitates easy file uploading.
i18n Keeps track of the selected locale during a user's session.
logger Provides simple logging by outputting the name of the action being
executed.

Using interceptors
<?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.devMode" value="true" />
<package name="helloworld" extends="struts-default">
<action name="hello"
class="com.xyz.HelloWorldAction"
method="execute">
<interceptor-ref name="params"/>
<interceptor-ref name="timer" />
<result name="success">/HelloWorld.jsp</result>
</action>
</package>
</struts>

Topics to be covered in next session
• Struts 2
• Struts Action Class
• Validation
• Control Tags
• Data Tags

Thank you!

Struts 2 - Introduction

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