Struts Framework Interview Questions And Answers
Jakarta Apache Struts 2 is an 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.
Apache Struts 2 was originally known as WebWork 2. After working independently for several years, the WebWork and Struts communities joined forces to create Struts2. This new version of Struts is simpler to use and closer to how Struts was always meant to be.
11. What are difference between ActionErrors and ActionMessage?
ActionMessage: A class that encapsulates messages. Messages can be either global or they are specific to a particular bean property. Each individual message is described by an ActionMessage object, which contains a message key (to be looked up in an appropriate message resources database), and up to four placeholder arguments used for parametric substitution in the resulting message. ActionErrors: A class that encapsulates the error messages being reported by the validate() method of an ActionForm. Validation errors are either global to the entire ActionForm bean they are associated with, or they are specific to a particular bean property (and, therefore, a particular input field on the corresponding form).
12. What are Tag Libraries provided with Struts?
Struts provides a number of tag libraries that helps to create view components easily. These tag libraries are: a) Bean Tags: Bean Tags are used to access the beans and their properties. b) HTML Tags: HTML Tags provides tags for creating the view components like forms, buttons, etc.. c) Logic Tags: Logic Tags provides presentation logics that eliminate the need for scriptlets. d) Nested Tags: Nested Tags helps to work with the nested context.
13. What are the components of Struts?
Struts is based on the MVC design pattern. Struts components can be categories into Model, View and Controller. Model: Components like business logic / business processes and data are the part of Model. View: JSP, HTML etc. are part of View Controller: Action Servlet of Struts is part of Controller components which works as front controller to handle all the requests.
14. What are the disadvantages of Struts?
Struts is very robust framework and is being used extensively in the industry. But there are some disadvantages of the Struts: a) High Learning Curve Struts requires lot of efforts to learn and master it. For any small project less experience developers could spend more time on learning the Struts. b) Harder to learn Struts are harder to learn, benchmark and optimize.
15. What are the uses of tiles-def.xml file, resourcebundle.properties file, validation.xml file?
tiles-def.xml is is an xml file used to configure tiles with the struts application. You can define the layout / header / footer / body content for your View. See more at http://www.roseindia.net/struts/using-tiles-defs-xml.shtml. The resourcebundle.properties file is used to configure the message (error/ other messages) for the struts applications. The file validation.xml is used to declare sets of validations that should be applied to Form Beans. Fpr more information please visit http://www.roseindia.net/struts/address_struts_validator.shtml.
16. What do you understand by DispatchAction?
DispatchAction is an action that comes with Struts 1.1 or later, that lets you combine Struts actions into one class, each with their own method. The org.apache.struts.action.DispatchAction class allows multiple operation to mapped to the different functions in the same Action class. For example: A package might include separate RegCreate, RegSave, and RegDelete Actions, which just perform different operations on the same RegBean object. Since all of these operations are usually handled by the same JSP page, it would be handy to also have them handled by the same Struts Action. A very simple way to do this is to have the submit button modify a field in the form which indicates which operation to perform. SAVE SAVE AS NEW DELETE Then, in the Action you can setup different methods to handle the different operations, and branch to one or the other depending on which value is passed in the dispatch field. String dispatch = myForm.getDispatch(); if ("create".equals(dispatch)) { ... if ("save".equals(dispatch)) { ... The Struts Dispatch Action [org.apache.struts.actions] is designed to do exactly the same thing, but without messy branching logic. The base perform method will check a dispatch field for you, and invoke the indicated method. The only catch is that the dispatch methods must use the same signature as perform. This is a very modest requirement, since in practice you usually end up doing that anyway. To convert an Action that was switching on a dispatch field to a DispatchAction, you simply need to create methods like this public ActionForward create( ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { ... public ActionForward save( ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { ... Cool. But do you have to use a property named dispatch? No, you don't. The only other step is to specify the name of of the dispatch property as the "parameter" property of the action-mapping. So a mapping for our example might look like this: If you wanted to use the property "o" instead, as in o=create, you would change the mapping to Again, very cool. But why use a JavaScript button in the first place? Why not use several buttons named "dispatch" and use a different value for each? You can, but the value of the button is also its label. This means if the page designers want to label the button something different, they have to coordinate the Action programmer. Localization becomes virtually impossible. (Source: http://husted.com/struts/tips/002.html).
17. 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.
18. 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.
19. 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.
20. 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.
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