Struts Interview Questions and Answers for experienced

1. What is Struts?

   • Answer: Struts is a free, open-source framework for creating Java web applications based on the Model-View-Controller (MVC) design pattern. It simplifies the development process by providing a structured approach to building web applications.

2. Explain the MVC architecture in Struts.

   • Answer: In Struts, the Model represents the business logic and data, the View handles the presentation to the user (JSPs, etc.), and the Controller (ActionServlet) manages user requests and interacts with the Model and View.

3. What is ActionServlet in Struts?

   • Answer: ActionServlet is the heart of Struts. It's a servlet that acts as the central controller, receiving all incoming requests, intercepting them, and dispatching them to the appropriate Action class based on the configuration in struts-config.xml.

4. Explain the role of struts-config.xml.

   • Answer: struts-config.xml is the configuration file for Struts. It defines the mapping between incoming requests (URLs) and Action classes, as well as form beans, data sources, and other crucial components of the application.

5. What are Action classes in Struts?

   • Answer: Action classes are Java classes that handle user requests. They process the request, interact with the model to perform business logic, and return a result that determines the next view to display.

6. What are ActionForms in Struts?

   • Answer: ActionForms are JavaBeans that encapsulate data submitted by the user through HTML forms. They provide data validation and simplify data handling in the Action classes.

7. What are Interceptors in Struts?

   • Answer: Interceptors are pluggable components that provide pre- and post-processing capabilities for Action invocations. They allow developers to add functionalities like logging, security checks, and exception handling without modifying the Action classes themselves.

8. Explain the concept of Tiles in Struts.

   • Answer: Tiles is a templating framework integrated into Struts that allows developers to create reusable UI components (tiles) and assemble them dynamically to build complex layouts. This promotes code reusability and maintainability.

9. How do you handle exceptions in Struts?

   • Answer: Exceptions can be handled using exception handling mechanisms within Action classes or through global exception handling mechanisms configured in struts-config.xml (or by using interceptors).

10. How to perform data validation in Struts?

    • Answer: Data validation can be implemented within ActionForms using validate() method, using custom validators, or through the use of validation frameworks integrated with Struts.

11. What is the difference between Struts 1 and Struts 2?

    • Answer: Struts 2 is a significant improvement over Struts 1. It utilizes a more streamlined architecture (using a value stack instead of ActionForms), offers better performance, and includes enhanced features like interceptors, annotations, and improved AJAX support.

12. Explain the concept of a ValueStack in Struts 2.

    • Answer: The ValueStack in Struts 2 is a data structure that holds the data for the current request. It simplifies data access in JSPs by eliminating the need for explicit getters and setters on Action classes.

13. How do you integrate Struts with other frameworks like Spring or Hibernate?

    • Answer: Integration with Spring typically involves using Spring's IoC container to manage Struts actions and other components. Integration with Hibernate involves using Hibernate for data persistence and accessing data within Struts actions.

14. What are OGNL expressions in Struts 2?

    • Answer: OGNL (Object-Graph Navigation Language) is an expression language used in Struts 2 to access and manipulate objects within the ValueStack. It simplifies data access and manipulation within JSPs.

15. Explain the use of result types in Struts.

    • Answer: Result types define how an Action responds after processing a request. Common result types include dispatcher (for JSPs), redirect, redirectAction, etc. They determine the next view or action to execute.

16. How do you handle file uploads in Struts?

    • Answer: File uploads are handled using the Commons FileUpload library integrated with Struts. The uploaded file data is typically accessed through a specialized ActionForm or directly in the Action class.

17. Describe the process of creating a simple Struts application.

    • Answer: It involves setting up the project, adding Struts libraries, configuring struts.xml (or struts-config.xml for Struts 1), creating Action classes and ActionForms (or utilizing POJOs in Struts 2), designing JSPs, and deploying the application to a servlet container.

18. What are the advantages and disadvantages of using Struts?

    • Answer: Advantages include a mature framework, established community support, clear MVC structure, and ease of development for simpler applications. Disadvantages include a steeper learning curve for complex applications, potential verbosity in Struts 1, and the rise of more modern frameworks.

19. How does Struts handle internationalization?

    • Answer: Struts supports internationalization through resource bundles which contain localized text and messages. This allows developers to easily create applications that support multiple languages.

20. What are some common security vulnerabilities in Struts applications and how can they be mitigated?

    • Answer: Common vulnerabilities include Cross-Site Scripting (XSS), SQL Injection, and Cross-Site Request Forgery (CSRF). Mitigation strategies involve input validation, parameterized queries (to prevent SQL injection), proper encoding of output (to prevent XSS), and implementing CSRF tokens.

21. How can you improve the performance of a Struts application?

    • Answer: Optimizations include using caching mechanisms, efficient database access, optimizing JSPs, using connection pooling, and proper use of interceptors and result types.

22. Explain the concept of a Struts plugin.

    • Answer: Plugins extend the functionality of Struts by adding new features or integrating third-party libraries. They can provide additional functionalities such as security enhancements, support for different databases, or integration with other frameworks.

23. How do you debug Struts applications?

    • Answer: Debugging involves using IDE debuggers to step through code, examining log files, using logging statements within Actions, and leveraging browser developer tools to inspect network requests and responses.

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