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Struts Interview Questions and FAQs - 1
Q: What is Struts?
A: 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.
Q: What is Jakarta Struts Framework?
A: 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.
Q: What is ActionServlet?
A: 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.
Q: How you will make available any Message Resources
Definitions file to the Struts Framework Environment?
A: 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\" />.
Q: What is Action Class?
A: 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.
Q: What is ActionForm?
A: 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.
Q: What is Struts Validator Framework?
A: 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.
Q: Give the Details of XML files used in Validator
Framework?
A: 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.
Q: How you will display validation fail errors on jsp page?
A: Following tag displays all the errors:
<html:errors/>
Q: How you will enable front-end validation based on the
xml in validation.xml?
A: 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.
Q: How to get data from the velocity page in a action
class?
A: We can get the values in the action classes by using
data.getParameter(\"variable name defined in the velocity page\");
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