Introduction to Struts Framework and Struts Interceptors

1. STRUTS
INTERCEPTORS
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2. Agenda
 What is Apache Struts 2.x ?
 Features of Apache Struts 2.x
 How Struts 2.x works ?
 Struts 2.x Architecture Overview
 Struts 2.0 MVC Components
 Request – Response Pipeline
 Interceptors
 Need of Interceptors
 Understanding the Difference Between Filters & Interceptors
 Configuring Interceptor
 Frameworks(In-built) Interceptors
 Custom Inceptors
 Disadvantages of Struts
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3. What is Apache Struts 2.x?
 Apache Struts 2 is an Open Source, elegant &
extensible framework for creating enterprise-ready
Java web applications
 The framework is designed to streamline the full
development cycle, from building, to deploying, to
maintaining applications over time
 It is Action Based Framework
 Cerate's web application using MVC 2
architecture
 Apache Struts offer two major version
 Struts 1.x
 Struts 2.x
 Struts 2 = WebWork + Struts
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4. Features of Struts 2.x
 MVC Framework
 Struts provides a unified framework for deploying
servlet and JSP applications that use the MVC
architecture
 A Set of JSP Custom Tag Libraries
 Struts provides custom tag libraries for outputting
bean properties, generating HTML forms, iterating
over various types of data structures, and
conditionally outputting HTML
 A Collection of Utilities
 Struts provides utility classes to handle many of the
most common tasks in Web application development
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5. Features of Struts 2.x
continued…
 Centralized file-based configuration
 Rather then hard-coding information into Java
programs, many Struts values are represented in
XML or property files. This loose coupling means
that many changes can be made without
modifying or recompiling Java code, and that
wholesale changes can be made by editing a
single file. This approach also lets Java and Web
developers focus on their specific tasks
(implementing business logic, presenting certain
values to clients, etc.) without needing to know
about the overall system layout
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6. Features of Struts 2.x
continued…
 HTML tags
Apache Struts provides a set of
custom JSP tags to create HTML
forms that are associated with
JavaBeans components. This
bean/form association serves two
useful purposes:
It lets you get initial form-field values from
Java objects
It lets you redisplay forms with some or all
previously entered values intact
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7. Features of Struts 2.x
continued…
 Form field validation
 Apache Struts has builtin capabilities for checking
that form values are in the required format. If
values are missing or in an improper format, the
form can be automatically redisplayed with error
messages and with the previously entered values
maintained
 This validation can be performed on the server (in
Java), or both on the server and on the client (in
JavaScript)
 Consistent approach
 Struts encourages consistent use of MVC
throughout your app
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8. 8 How Struts 2.x works?
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9. Struts 2.x Architecture Overview
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10. Struts 2.x Architecture Overview
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11. Struts 2.0 MVC Components
Core components of the framework
 Controller:-
 Filter Dispatcher:-
 First component that start processing that is why this type of
MVC is called front controller MVC
 Looks at the request and apply the appropriate action.
 Struts framework handles all of the controller work.
 Its configured in web.xml
 Interceptors:-
 Can execute code before and after an Action is executed.
 They can be configured per action basis.
 Can be used for data validation, file upload, double submit
guards.
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12. Struts 2.0 MVC Components
contd.
 Model:-
 Implemented by action class
 For model you can use any data access
technologies like JDBC,EJB,Hibernate
 View
 Its your result part. It can be JSP,JSTL,JSF etc.
 Presentation part of the MVC
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13. Request – Response Pipeline
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14. Need of Interceptors
 Many Actions share common concerns
 Some Actions need input validated
 The framework makes it easy to share
solutions to these concerns using an
"Interceptor" strategy
 Interceptors can execute code before and after
an Action is invoked
 Interceptors "set the stage" for the Action
classes
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15. 15 Interceptor Looks like Filters
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16. Understanding the Difference
Filters Interceptors
Based on Servlet Specification Based on Struts2.
Executes on the pattern matches on the
request.
Executes for all the request qualifies for
a front controller( A Servlet filter ).And
can be configured to execute additional
interceptor for a particular action
execution.
Not configurable method calls Methods in the Interceptors can be
configured whether to execute or not by
means of excludemethods or
includeMethods
A Servlet Filter is used in the web layer
only, you can’t use it outside of a web
context.
Interceptors can be used anywhere.
That’s the main difference.
for authentication of web pages you
would use a servlet filter
For security stuff in your business layer
or logging/bugtracing (a.k.a.
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17. Understanding Interceptors
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18. Understanding Interceptors
Continued…
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19. Configuring Interceptor
 <action name="login"
class=“pack.className"> <interceptor-ref
name="timer"/>
<interceptor-ref name="logger"/>
<result name="input">login.jsp</result>
<result name="success“
type="redirectAction">home</result>
</action>
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20. Frameworks(In-built)
Interceptors
 ParametersInterceptor
 It sets request parameter into the action
 This interceptor gets all parameters from request
and sets them on the value stack, typically
resulting in the values submitted in a form request
being applied to an action in the value stack
 AliasInterceptor
 Converts similar parameters that may be named
differently between requests
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21. Frameworks(In-built)
Interceptors cont..
 ServletConfigInterceptor
 An interceptor which sets action properties based
on the interfaces an action implements
 For example, if the action implements
ServletRequestAware interface then setting of
HttpServletRequest is done by this interceptor
 This interceptor is designed to set all properties
an action needs if it's aware of servlet
parameters, the servlet context, the session, etc
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22. Frameworks(In-built)
Interceptors cont..
 WorkflowInterceptor
 An interceptor that makes sure there are not validation
errors before allowing the interceptor chain to continue
 This interceptor does not perform any validation
 ValidationInterceptor
 This interceptor runs the action through the standard
validation framework
 It checks the action against any validation rules (found in
files such as ActionClass-validation.xml)
 The workflow of the action request does not change due to
this interceptor
 Rather, this interceptor is often used in conjuction with
the workflow interceptor
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23. Disadvantages of Struts
 Bigger learning curve
 To use MVC with the standard RequestDispatcher, you need to
be comfortable with the standard JSP and servlet APIs. To use
MVC with Struts, you have to be comfortable with the standard
JSP and servlet APIs and a large and elaborate framework that is
almost equal in size to the core system. This drawback is
especially significant with smaller projects, near-term deadlines,
and less experienced developers; you could spend as much time
learning Struts as building your actual system
 Poor documentation
 Compared to the standard servlet and JSP APIs, Struts has
fewer online resources, and many first-time users find the online
Apache documentation confusing and poorly organized. There
are also fewer books on Apache Struts than on standard servlets
and JSP
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24. Disadvantages of Struts
 Less transparent
 With Struts applications, there is a lot more going on
behind the scenes than with normal Java-based Web
applications. As a result, Struts applications are:
 Harder to understand
 Harder to benchmark and optimize
 Rigid approach
 The flip side of the benefit that Struts encourages a
consistent approach to MVC is that Struts makes it
difficult (but by no means impossible) to use other
approaches
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25. 25 Thank You
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