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Struts Interview Questions and Answers
1. What is Struts?
Struts is a web page development framework and an open source software that helps developers build web applications quickly and easily. Struts combines Java Servlets, Java Server Pages, custom tags, and message resources into a unified framework. It is a cooperative, synergistic platform, suitable for development teams, independent developers, and everyone between.
2. How is the MVC design pattern used in Struts framework?
In the MVC design pattern, application flow is mediated by a central Controller. The Controller delegates requests to an appropriate handler. The handlers are tied to a Model, and each handler acts as an adapter between the request and the Model. The Model represents, or encapsulates, an application's business logic or state. Control is usually then forwarded back through the Controller to the appropriate View. The forwarding can be determined by consulting a set of mappings, usually loaded from a database or configuration file. This provides a loose coupling between the View and Model, which can make an application significantly easier to create and maintain.
Controller--Servlet controller which supplied by Struts itself; View --- what you can see on the screen, a JSP page and presentation components; Model --- System state and a business logic JavaBeans.
3. Who makes the Struts?
Struts is hosted by the Apache Software Foundation(ASF) as part of its Jakarta project, like Tomcat, Ant and Velocity.
4. Why it called Struts?
Because the designers want to remind us of the invisible underpinnings that hold up our houses, buildings, bridges, and ourselves when we are on stilts. This excellent description of Struts reflect the role the Struts plays in developing web applications.
5. Do we need to pay the Struts if being used in commercial purpose?
No. Struts is available for commercial use at no charge under the Apache Software License. You can also integrate the Struts components into your own framework just as if they were writtern in house without any red tape, fees, or other hassles.
6. What are the core classes of Struts?
Action, ActionForm, ActionServlet, ActionMapping, ActionForward are basic classes of Structs.
7. What is the design role played by Struts?
The role played by Structs is controller in Model/View/Controller(MVC) style. The View is played by JSP and Model is played by JDBC or generic data source classes. The Struts controller is a set of programmable components that allow developers to define exactly how the application interacts with the user.
8. How Struts control data flow?
Struts implements the MVC/Layers pattern through the use of ActionForwards and ActionMappings to keep control-flow decisions out of presentation layer.
9. What configuration files are used in Struts?
These two files are used to bridge the gap between the Controller and the Model.
10. What helpers in the form of JSP pages are provided in Struts framework?
11. Is Struts efficient?
- The Struts is not only thread-safe but thread-dependent(instantiates each Action once and allows other requests to be threaded through the original object.
- ActionForm beans minimize subclass code and shorten subclass hierarchies
- The Struts tag libraries provide general-purpose functionality
- The Struts components are reusable by the application
- The Struts localization strategies reduce the need for redundant JSPs
- The Struts is designed with an open architecture--subclass available
- The Struts is lightweight (5 core packages, 5 tag libraries)
- The Struts is open source and well documented (code to be examined easily)
- The Struts is model neutral
12. What is Jakarta Struts Framework?
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.
13. What is ActionServlet?
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.
14. How you will make available any Message Resources Definitions file to the Struts Framework Environment?
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.
< message-resources parameter= MessageResources / >
15. What is Action Class?
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.
16. Write code of any Action Class?
Here is the code of Action Class that returns the ActionForward object.
public class TestAction extends Action
public ActionForward execute(
HttpServletResponse response) throws Exception
17. What is ActionForm?
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.
18. What is Struts Validator Framework?
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.
19. Give the Details of XML files used in Validator Framework?
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.
How you will display validation fail errors on jsp page? - The following tag displays all the errors:
< html:errors/ >
20. How you will enable front-end validation based on the xml in validation.xml?
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