1. What is Struts framework?
Struts is a Java-based open-source framework used for developing web applications. It follows the Model-View-Controller (MVC) architecture and is based on the Java Servlet and JavaServer Pages (JSP) technologies.

2. What is the advantage of using Struts framework?
The main advantage of using Struts is that it provides a clear separation of concerns between model, view, and controller components, making development and maintenance easier. It also provides features like form validation, localization, and easy integration with other frameworks.

3. Explain the key components of Struts framework.
The key components of the Struts framework are:
– ActionServlet: Acts as a front controller for handling requests and managing the workflow.
– Action classes: Implement the business logic and interact with the model.
– ActionForm: Represents the form data submitted by the user and provides data validation.
– JSP pages: Display the output to the users.
– Configuration files: Define the mapping between URLs, actions, and resources.

4. What is the purpose of the struts-config.xml file?
The struts-config.xml file is used to configure the actions, forms, mappings, and other resources in a Struts application. It defines the overall structure and behavior of the application, including the mapping between URLs and actions.

5. How is validation performed in Struts?
Struts provides built-in support for form validation. It uses the validator framework, which allows developers to define simple or complex validation rules for form fields. These rules can be defined in XML or programmatic configuration files.

6. Explain the difference between ActionForm and DynaActionForm.
ActionForm is a regular Java bean that encapsulates the form data submitted by the user. The properties of the ActionForm correspond to the fields of the form. On the other hand, DynaActionForm is a variant of ActionForm that allows dynamic (runtime) properties to be added to the form based on the form data.

7. What is the purpose of the ActionMapping class?
ActionMapping class is used to define the mapping between an incoming request and the corresponding Action class. It specifies the URL pattern, the form bean associated with the action, and the forward or redirect to be performed after executing the action.

8. How can you configure database connectivity in Struts?
Database connectivity in Struts can be achieved through data source configuration. The configuration can be done in the struts-config.xml file by defining the data source information, such as driver class, URL, username, and password.

9. What is the difference between forward and redirect in Struts?
Forward is a server-side redirect where the control is transferred to another resource (JSP, Servlet) on the server without the client’s knowledge. Redirect, on the other hand, is a client-side redirect where the control is transferred to a different URL, and the client sends a new request to that URL.

10. How can you handle exceptions in Struts?
Struts provides exception handling through the ExceptionHandler interface and the struts-config.xml file. Exceptions can be handled globally or at the level of individual actions. The ExceptionHandler interface allows the developer to customize the error handling logic.

11. What is the purpose of the DispatchAction in Struts?
DispatchAction is a subclass of Action that allows grouping related actions into a single class. It uses a parameter in the request to determine which specific action to perform. DispatchAction simplifies the configuration by eliminating the need to define multiple Action mappings.

12. How can you use internationalization (i18n) in Struts?
Struts provides built-in support for internationalization. It allows developers to define resource bundles containing localized strings for different languages. These resource bundles can be used in JSP pages or Action classes to display messages in the user’s preferred language.

13. What are the different types of interceptors in Struts?
The different types of interceptors in Struts are:
– Pre-Interceptors: Executed before the action is invoked.
– Post-Interceptors: Executed after the action is invoked and before the output is rendered.
– Exception Interceptors: Executed when an exception occurs during action processing.

14. Explain the role of ActionForward in Struts.
ActionForward represents the target resource (JSP, HTML, or another action mapping) to which control is transferred after executing an action. It encapsulates the forward or redirect information along with path details.

15. What is the purpose of the Struts tag library?
The Struts tag library provides custom tags that simplify the development of Struts-based applications. These tags encapsulate commonly used functionality, such as form fields, HTML rendering, internationalization, and action mapping.

16. How can you use Tiles framework in Struts?
Tiles is a templating framework that allows developers to define reusable page layouts and insert dynamic content into the layout. Struts provides integration with Tiles, allowing developers to define the overall structure of web pages and reuse the layout across multiple pages.

17. What is the difference between Struts 1 and Struts 2?
Struts 1 is an older version of the framework, while Struts 2 is a newer version that provides enhanced features and better modularization. Struts 2 is built on top of the WebWork framework and offers improved testability, extensibility, and ease of use compared to Struts 1.

18. How can you handle form data in Struts?
Struts provides several mechanisms to handle form data, such as using ActionForm beans, DynaActionForm for dynamic forms, or directly accessing the HttpServletRequest object in the Action class. Form data can be accessed using getters and setters or through the request object’s parameter map.

19. What is the role of the Struts configuration file struts-config.xml?
The struts-config.xml file is used to define the overall structure and configuration of the Struts application. It contains configuration elements for actions, forms, mappings, forwards, exception handling, and other resources.

20. How can you implement AJAX functionality in Struts?
To implement AJAX functionality in Struts, you can use JavaScript frameworks like jQuery or Prototype to make asynchronous requests to the server. By using Struts actions as endpoints, you can process the AJAX requests and return JSON or XML responses to update the client-side content dynamically.

1. What is the difference between Struts 1 and Struts 2?
Struts 1 is based on the Model-View-Controller (MVC) design pattern and uses ActionForms for data handling, while Struts 2 is built on a newer architecture called the WebWork framework and uses POJO-based actions.

2. Explain the concept of Interceptors in Struts 2?
Interceptors in Struts 2 are responsible for intercepting requests and responses. They provide a way to perform additional processing before and after the execution of an action. Interceptors can be used for tasks such as validation, authentication, logging, and exception handling.

3. What is the purpose of the Struts.xml file?
The Struts.xml file is the main configuration file in Struts 2. It defines the mapping between URLs and actions, as well as other configuration details like global result types, interceptors, etc.

4. How can you handle file uploads in Struts 2?
Struts 2 provides a built-in file upload mechanism using the `` tag. By default, it stores the uploaded file in a temporary location and provides a reference to it in the action class. The file can then be processed or saved to a desired location.

5. How is validation implemented in Struts 2?
Struts 2 provides a powerful validation framework based on XML configuration. The validation rules can be defined using annotations in the action class or through XML configuration files. Validation can be performed on both server-side and client-side.

6. What is the use of the Struts PrepareInterceptor?
The Struts PrepareInterceptor is used to prepare the action for execution. It sets the property values on the action before invoking the action method. It performs tasks like parameter population, model-driven initialization, and validation preparation.

7. How do you handle internationalization (i18n) in Struts 2?
Struts 2 provides built-in support for internationalization. It uses resource bundles to store localized strings. The framework automatically detects the user’s locale and selects the appropriate resource bundle for rendering localized content.

8. What is the difference between the Redirect and Chain result types?
When the Redirect result type is used, the client browser is redirected to a new URL, and a new request is generated. On the other hand, the Chain result type simply forwards the request to a new action, without the client being aware of the change.

9. What is the purpose of the Dynamic Method Invocation (DMI) feature in Struts 2?
Dynamic Method Invocation allows you to invoke action methods dynamically using the value specified in the `method` parameter of the request. It allows for greater flexibility in dynamically handling actions.

10. How can you integrate Struts 2 with Spring?
Struts 2 can be easily integrated with Spring by using the `struts2-spring-plugin`. This plugin provides seamless integration between the Struts 2 framework and the Spring container, allowing you to leverage Spring’s powerful dependency injection and AOP features.

11. Explain the concept of OGNL (Object-Graph Navigation Language) in Struts 2.
OGNL is an expression language used in Struts 2 for accessing and manipulating object properties. It provides a concise syntax for working with objects, arrays, collections, and maps. OGNL expressions are commonly used in Struts 2 for data binding and accessing action properties.

12. What are the different result types available in Struts 2?
Struts 2 provides a variety of result types, including `dispatcher`, `redirect`, `chain`, `redirectAction`, `stream`, `freemarker`, `velocity`, `jasper`, `json`, `xml`, etc. These result types determine how the output generated by the action is handled and rendered.

13. How can you handle exceptions in Struts 2?
Struts 2 provides a global exception mapping mechanism to handle exceptions. By configuring the `` in the Struts.xml file, you can map exceptions to specific error pages or actions to handle them gracefully.

14. What is the purpose of the TokenInterceptor in Struts 2?
The TokenInterceptor in Struts 2 is used for preventing duplicate form submissions. It generates a unique token for each request and verifies it during form submission. If the token is not valid or has already been used, it prevents the action from being executed.

15. How can you unit test Struts 2 actions?
Struts 2 actions can be unit tested using frameworks like JUnit. By instantiating the action class, setting the required properties, and invoking the action method, you can test the behavior and functionality of the action in isolation.

16. What is the purpose of the DeferredResult support in Struts 2?
The DeferredResult support in Struts 2 allows long-polling and asynchronous processing of requests. It provides a way to defer the response until the desired result is available, improving the efficiency and scalability of the application.

17. How can you achieve AJAX support in Struts 2?
Struts 2 provides out-of-the-box support for AJAX requests. It offers tags like `` and `` that can be easily configured to perform AJAX requests. Additionally, Struts 2 provides custom AJAX result types to handle AJAX responses.

18. What is the JSON Plugin in Struts 2?
The JSON Plugin in Struts 2 is used to generate JSON responses. It allows you to convert Java objects to JSON format and vice versa. The JSON Plugin also provides support for JSON validation and JSON-based result types.

19. How can you integrate Hibernate with Struts 2?
Hibernate can be easily integrated with Struts 2 by using the `struts2-hibernate-plugin`. This plugin provides seamless integration between the Struts 2 framework and Hibernate, allowing you to leverage Hibernate’s powerful ORM capabilities.

20. Explain the concept of Convention over Configuration in Struts 2.
Convention over Configuration is an architectural principle followed by Struts 2, where sensible defaults and naming conventions are used to reduce configuration. It allows for a simplified development process by minimizing the need for explicit configuration.