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Struts Interview Questions
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Q:
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What
is Struts?
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A:
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The core of the Struts framework
is a flexible control layer based on standard technologies like Java
Servlets, JavaBeans, ResourceBundles, and XML, as well as various Jakarta
Commons packages. Struts encourages application architectures based on the
Model 2 approach, a variation of the classic Model-View-Controller (MVC)
design paradigm.
Struts
provides its own Controller component and integrates with other technologies
to provide the Model and the View. For the Model, Struts can interact with
standard data access technologies, like JDBC and EJB, as well as most any
third-party packages, like Hibernate, iBATIS, or Object Relational Bridge.
For the View, Struts works well with JavaServer Pages, including JSTL and
JSF, as well as Velocity Templates, XSLT, and other presentation systems.
The
Struts framework provides the invisible underpinnings every professional web
application needs to survive. Struts helps you create an extensible
development environment for your application, based on published standards and
proven design patterns.
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[ Received from Ramakrishna
Potluri ]
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1.
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Q:
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What
is Jakarta Struts Framework?
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A:
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Jakarta Struts is open source implementation
of MVC (Model-View-Controller) pattern for the development of web based
applications. Jakarta Struts is robust architecture and can be used for the
development of application of any size. Struts framework makes it much easier
to design scalable, reliable Web applications with Java.
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[ Received from Dhiraj Sharma]
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2.
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Q:
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What
is ActionServlet?
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A:
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The class org.apache.struts.action.ActionServlet
is the called the ActionServlet. In the the Jakarta Struts Framework this
class plays the role of controller. All the requests to the server goes
through the controller. Controller is responsible for handling all the requests.
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[ Received from Dhiraj Sharma]
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3.
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Q:
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How
you will make available any Message Resources Definitions file to the Struts
Framework Environment?
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A:
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T Message Resources Definitions
file are simple .properties files and these files contains the messages that
can be used in the struts project. Message Resources Definitions files can be
added to the struts-config.xml file through <message-resources /> tag.
Example:
<message-resources
parameter=\"MessageResources\" />.
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[ Received from Dhiraj Sharma]
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4.
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Q:
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What
is Action Class?
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A:
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The Action Class is part of the
Model and is a wrapper around the business logic. The purpose of Action Class
is to translate the HttpServletRequest to the business logic. To use the
Action, we need to Subclass and overwrite the execute() method. In the Action
Class all the database/business processing are done. It is advisable to
perform all the database related stuffs in the Action Class. The
ActionServlet (commad) passes the parameterized class to Action Form using
the execute() method. The return type of the execute method is ActionForward
which is used by the Struts Framework to forward the request to the file as
per the value of the returned ActionForward object.
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[ Received from Dhiraj Sharma]
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5.
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Q:
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What
is ActionForm?
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A:
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An ActionForm is a JavaBean that
extends org.apache.struts.action.ActionForm. ActionForm maintains the session
state for web application and the ActionForm object is automatically
populated on the server side with data entered from a form on the client
side.
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[ Received from Dhiraj Sharma]
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6.
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Q:
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What
is Struts Validator Framework?
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A:
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Struts Framework provides the
functionality to validate the form data. It can be use to validate the data
on the users browser as well as on the server side. Struts Framework emits
the java scripts and it can be used validate the form data on the client
browser. Server side validation of form can be accomplished by sub classing
your From Bean with DynaValidatorForm class.
The
Validator framework was developed by David Winterfeldt as third-party add-on
to Struts. Now the Validator framework is a part of Jakarta Commons project
and it can be used with or without Struts. The Validator framework comes
integrated with the Struts Framework and can be used without doing any extra
settings.
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[ Received from Dhiraj Sharma]
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7.
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Q:
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Give
the Details of XML files used in Validator Framework?
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A:
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The Validator Framework uses two
XML configuration files validator-rules.xml and validation.xml. The
validator-rules.xml defines the standard validation routines, these are
reusable and used in validation.xml. to define the form specific validations.
The validation.xml defines the validations applied to a form bean.
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[ Received from Dhiraj Sharma]
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8.
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Q:
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How
you will display validation fail errors on jsp page?
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A:
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Following tag displays all the
errors:
<html:errors/>
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[ Received from Dhiraj Sharma]
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9.
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Q:
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How
you will enable front-end validation based on the xml in validation.xml?
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A:
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The <html:javascript> tag to
allow front-end validation based on the xml in validation.xml. For example
the code: <html:javascript formName=\"logonForm\"
dynamicJavascript=\"true\" staticJavascript=\"true\"
/> generates the client side java script for the form \"logonForm\"
as defined in the validation.xml file. The <html:javascript> when added
in the jsp file generates the client site validation script.
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[ Received from Dhiraj Sharma]
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10.
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Q:
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How
to get data from the velocity page in a action class?
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A:
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We can get the values in the
action classes by using data.getParameter(\"variable name defined in the
velocity page\");
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