Spring MVC Interview Questions and Answers for freshers

1. What is Spring MVC?

   • Answer: Spring MVC (Model-View-Controller) is a Java framework that provides a flexible and elegant way to build web applications. It's part of the larger Spring Framework and simplifies the development process by separating concerns into distinct layers: Model (data), View (presentation), and Controller (handling requests and responses).

2. Explain the Model-View-Controller (MVC) architectural pattern.

   • Answer: MVC separates application concerns into three interconnected parts: Model (data and business logic), View (user interface), and Controller (handling user input and updating the model and view). The controller receives requests, interacts with the model to process data, and then selects an appropriate view to display the results to the user.

3. What are the core components of Spring MVC?

   • Answer: Core components include DispatcherServlet (front controller), HandlerMapping (maps requests to controllers), Controller (processes requests), ModelAndView (holds model and view information), ViewResolver (selects the view), and View (renders the response).

4. What is the role of DispatcherServlet in Spring MVC?

   • Answer: DispatcherServlet is the central component, acting as the front controller. It intercepts all incoming requests, delegates them to appropriate controllers, and handles the response.

5. Explain HandlerMapping in Spring MVC.

   • Answer: HandlerMapping is responsible for mapping incoming requests to the appropriate controller. It determines which controller method should handle a specific request based on URL patterns or other criteria.

6. What are different types of Handler Mappings available in Spring MVC?

   • Answer: Common types include BeanNameUrlHandlerMapping (maps requests based on bean names), SimpleUrlHandlerMapping (maps requests based on URL patterns), and RequestMappingHandlerMapping (uses annotations like @RequestMapping).

7. How does a Controller handle requests in Spring MVC?

   • Answer: Controllers are annotated with @Controller or @RestController. They contain methods annotated with @RequestMapping that handle specific HTTP requests (GET, POST, PUT, DELETE). These methods process the request data, interact with the model, and return a ModelAndView object or a specific data type if using @RestController.

8. Explain the @RequestMapping annotation.

   • Answer: @RequestMapping maps HTTP requests to specific controller methods. It can specify URL patterns, HTTP methods (GET, POST, etc.), consumes (request content type), and produces (response content type).

9. What is the difference between @Controller and @RestController annotations?

   • Answer: @Controller marks a class as a controller that returns a ModelAndView object. @RestController is a specialized annotation that combines @Controller and @ResponseBody, automatically converting the returned object into HTTP response body (e.g., JSON or XML).

10. What is ModelAndView in Spring MVC?

    • Answer: ModelAndView is a class that holds both the model data (attributes) and the view name. The controller returns a ModelAndView object to the DispatcherServlet, which then uses it to select the view and populate it with the model data.

11. Explain ViewResolver in Spring MVC.

    • Answer: ViewResolver is responsible for resolving a logical view name (returned by the controller) into an actual View object. It determines which technology to use to render the view (e.g., JSP, Thymeleaf, FreeMarker).

12. What are different types of ViewResolvers?

    • Answer: InternalResourceViewResolver (for JSPs), UrlBasedViewResolver (for external views), BeanNameViewResolver (maps view names to beans), and others depending on the templating engine used (ThymeleafViewResolver, FreeMarkerViewResolver).

13. How do you handle exceptions in Spring MVC?

    • Answer: Use the @ExceptionHandler annotation in a controller or a dedicated exception handler class to catch and handle exceptions. This allows for customized error pages or responses.

14. What is data binding in Spring MVC?

    • Answer: Data binding automatically converts HTTP request parameters into Java objects. Spring MVC uses a DataBinder to handle this process, populating the properties of a controller method's parameter objects with values from the request.

15. Explain the use of @PathVariable annotation.

    • Answer: @PathVariable extracts values from the URI path and binds them to method parameters. For example, in a URL like /users/123, @PathVariable("id") int userId would extract "123" and assign it to the userId variable.

16. Explain the use of @RequestParam annotation.

    • Answer: @RequestParam extracts parameters from the query string or form data and binds them to method parameters. For example, in a URL like /search?query=spring, @RequestParam("query") String searchTerm would extract "spring" and assign it to searchTerm.

17. What is a Validator in Spring MVC?

    • Answer: A Validator is used to validate user input. It implements the Validator interface and checks if data meets certain criteria. Validation errors are typically added to a BindingResult object.

18. How to implement form validation in Spring MVC?

    • Answer: Use the @Valid annotation on the command object in the controller method. Implement a Validator or use annotations like @NotBlank, @Size, etc., on the command object's fields. The BindingResult object will contain validation errors.

19. What is the role of Interceptor in Spring MVC?

    • Answer: Interceptors are used to perform pre-processing or post-processing tasks before or after controller method execution. They are similar to filters but operate within the Spring MVC framework.

20. How to use MultipartResolver for file uploads in Spring MVC?

    • Answer: Configure a MultipartResolver (e.g., CommonsMultipartResolver) in the Spring configuration to handle file uploads. Use the MultipartFile parameter type in controller methods to access uploaded files.

21. Explain the concept of Spring Security in the context of Spring MVC.

    • Answer: Spring Security provides authentication and authorization for Spring MVC applications. It secures web applications by protecting URLs, enforcing access control, and managing user authentication.

22. What are different ways to configure Spring MVC?

    • Answer: Spring MVC can be configured using XML configuration files, Java-based configuration (@Configuration classes), or annotation-based configuration.

23. What is a Spring bean?

    • Answer: A Spring bean is an object managed by the Spring IoC container. It's created, configured, and managed by the container, promoting loose coupling and reusability.

24. What is dependency injection in Spring?

    • Answer: Dependency Injection is a design pattern where dependencies are provided to a class instead of being created within the class. Spring manages the creation and injection of dependencies.

25. Explain different types of dependency injection.

    • Answer: Constructor Injection (dependencies are injected through the constructor), Setter Injection (dependencies are injected through setter methods), and Field Injection (dependencies are injected directly into fields).

26. What is Inversion of Control (IoC) in Spring?

    • Answer: IoC is a design principle where the control of object creation and management is inverted from the application code to the Spring container. The container manages the lifecycle of beans.

27. What is Aspect-Oriented Programming (AOP) in Spring?

    • Answer: AOP allows separating cross-cutting concerns (like logging, security, transaction management) from the core business logic. Spring AOP uses aspects to add these concerns without modifying the main code.

28. Explain the concept of advice in AOP.

    • Answer: Advice is the action taken by an aspect. It can be before, after, around, or after throwing advice, specifying when the action should be performed.

29. What is a Pointcut in AOP?

    • Answer: A Pointcut defines where advice should be applied. It specifies the join points (method calls, field access, etc.) where the advice should be executed.

30. What is a Joinpoint in AOP?

    • Answer: A Joinpoint is a specific point in the execution of a program, such as a method call or exception handling.

31. What is an Aspect in AOP?

    • Answer: An Aspect is a modular unit of cross-cutting concerns. It combines pointcuts and advice to define where and what action should be taken.

32. How to configure AOP in Spring?

    • Answer: AOP can be configured using XML configuration or annotations (@Aspect, @Before, @After, etc.).

33. What is Spring Data JPA?

    • Answer: Spring Data JPA simplifies data access with JPA (Java Persistence API). It provides a higher-level abstraction over JPA, reducing boilerplate code for database interactions.

34. How to use Spring Data JPA with Spring MVC?

    • Answer: Integrate Spring Data JPA repositories into your Spring MVC controllers to access and manipulate data. Spring manages the persistence context.

35. What are the benefits of using Spring MVC?

    • Answer: Benefits include simplified development, separation of concerns, testability, flexibility, and integration with other Spring modules.

36. What are some common Spring MVC interview questions?

    • Answer: Many questions focus on MVC architecture, core components, annotations (@RequestMapping, @Controller, @RestController, etc.), data binding, exception handling, and integration with other Spring features.

37. How to handle file uploads in Spring MVC?

    • Answer: Use MultipartFile in controller methods, configure MultipartResolver (like CommonsMultipartResolver), and handle file storage and processing accordingly.

38. How to implement RESTful APIs in Spring MVC?

    • Answer: Use @RestController, choose appropriate HTTP methods (@RequestMapping with GET, POST, PUT, DELETE), and return data directly (often as JSON or XML) using a suitable HTTP status code.

39. What are the best practices for building Spring MVC applications?

    • Answer: Follow MVC pattern strictly, use appropriate annotations, validate user input, handle exceptions gracefully, write unit tests, and keep code clean and maintainable.

40. How do you configure a view resolver for JSP in Spring MVC?

    • Answer: Use InternalResourceViewResolver, setting the prefix (e.g., "/WEB-INF/jsp/") and suffix (e.g., ".jsp").

41. How do you handle internationalization (i18n) in Spring MVC?

    • Answer: Use MessageSource to load messages from properties files, configure LocaleResolver, and use Spring's message tag library in JSPs or similar mechanisms in other view technologies.

42. Explain the concept of a servlet filter in the context of Spring MVC.

    • Answer: Servlet filters are a standard Java EE mechanism for intercepting HTTP requests before they reach the servlet container (and thus, before the DispatcherServlet). They can be used for tasks like logging, security, or encoding.

43. What is the difference between a filter and an interceptor in Spring MVC?

    • Answer: Filters operate at the servlet container level and are applied before Spring MVC's DispatcherServlet. Interceptors operate within the Spring MVC framework, after the request reaches the DispatcherServlet, allowing for more fine-grained control over the request lifecycle.

44. Explain the concept of a servlet listener in the context of Spring MVC.

    • Answer: Servlet listeners are used to monitor events in the servlet container lifecycle, such as application startup and shutdown. They can be used for tasks like initializing Spring context or performing cleanup operations.

45. How can you inject dependencies into a servlet filter or listener?

    • Answer: Typically, you can't directly inject dependencies into servlet filters or listeners using the standard Spring mechanisms. You would need to obtain the Spring context using WebApplicationContextUtils and manually retrieve the beans needed.

46. How to integrate Spring MVC with a database?

    • Answer: Use Spring Data JPA, Hibernate, or JDBC to interact with a database. Spring provides convenient mechanisms for configuring data sources and managing transactions.

47. What is a transaction in Spring MVC?

    • Answer: A transaction is a unit of work that ensures data consistency. In Spring, transactions guarantee that a set of database operations either complete successfully as a whole or roll back if any part fails.

48. How do you manage transactions in Spring MVC?

    • Answer: Use the @Transactional annotation at the method level or class level to define transactional boundaries. Spring's transaction management infrastructure ensures the atomicity and consistency of database operations.

49. Explain different transaction propagation types in Spring.

    • Answer: Transaction propagation defines how a new transaction should behave relative to an existing transaction. Options include REQUIRED, REQUIRES_NEW, SUPPORTS, MANDATORY, NOT_SUPPORTED, NEVER, NESTED.

50. What is the role of the `@Autowired` annotation?

    • Answer: `@Autowired` is used for dependency injection. It automatically wires dependencies based on type, allowing Spring to resolve and inject the appropriate bean.

51. What is the role of the `@Qualifier` annotation?

    • Answer: `@Qualifier` is used when you have multiple beans of the same type and need to specify which one should be injected. It provides a way to disambiguate the dependency.

52. What is the difference between `@Component`, `@Service`, `@Repository`, and `@Controller` annotations?

    • Answer: These are stereotype annotations providing metadata about the role of a Spring bean. `@Component` is a general-purpose stereotype. `@Service` is used for business logic classes. `@Repository` is for data access classes. `@Controller` is for MVC controllers.

53. Explain the concept of loose coupling in Spring.

    • Answer: Loose coupling means that components are minimally dependent on each other. Spring achieves this through dependency injection, allowing for flexibility and maintainability.

54. How do you perform unit testing in Spring MVC?

    • Answer: Use testing frameworks like JUnit and Mockito. Mock dependencies to isolate components and test them independently. Use Spring's testing support classes to easily create and configure Spring contexts.

55. How do you handle JSON data in Spring MVC?

    • Answer: Use Jackson or Gson for JSON serialization/deserialization. Add the appropriate dependency and configure a `MappingJackson2HttpMessageConverter` to handle JSON requests and responses.

56. How do you handle XML data in Spring MVC?

    • Answer: Use JAXB or similar libraries for XML processing. Configure a `MarshallingHttpMessageConverter` or `UnmarshallingHttpMessageConverter` to handle XML requests and responses.

57. What is Spring Boot?

    • Answer: Spring Boot simplifies the creation of Spring-based applications. It provides auto-configuration, embedded servers, and opinionated defaults to reduce boilerplate code.

58. What are the advantages of using Spring Boot with Spring MVC?

    • Answer: Spring Boot significantly streamlines Spring MVC development by providing faster setup, easier configuration, and reduced complexity.

59. How do you create a simple REST API using Spring Boot and Spring MVC?

    • Answer: Create a Spring Boot project, add the necessary dependencies, create a `@RestController` class with `@RequestMapping` methods, and use a tool like Postman to test the API.

60. What are some common tools used for testing Spring MVC applications?

    • Answer: JUnit, Mockito, Spring Test, AssertJ, and various mocking libraries are commonly used.

61. What are some best practices for securing Spring MVC applications?

    • Answer: Use Spring Security, validate user input, prevent SQL injection and cross-site scripting (XSS) attacks, use HTTPS, and follow secure coding practices.

62. How do you implement pagination in Spring MVC?

    • Answer: Use Spring Data JPA's `Pageable` interface to define pagination criteria and retrieve data in pages. Present pagination controls in the UI.

63. How do you implement sorting in Spring MVC?

    • Answer: Use Spring Data JPA's `Sort` interface to define sorting criteria and retrieve data in sorted order. Provide sorting options in the UI.

64. How to handle different HTTP methods (GET, POST, PUT, DELETE) in Spring MVC?

    • Answer: Use the `method` attribute in `@RequestMapping` to specify the allowed HTTP methods for a controller method.

65. What is the difference between a forward and a redirect in Spring MVC?

    • Answer: A forward is an internal server-side operation. A redirect sends a response to the client, causing the client to make a new request. Redirects change the URL in the browser's address bar.

66. How to configure Spring MVC to use Thymeleaf as a templating engine?

    • Answer: Add the Thymeleaf dependency, configure a ThymeleafViewResolver, and use Thymeleaf templates instead of JSPs.

67. How to configure Spring MVC to use FreeMarker as a templating engine?

    • Answer: Add the FreeMarker dependency, configure a FreeMarkerViewResolver, and use FreeMarker templates.

68. What is the role of the `@ResponseBody` annotation?

    • Answer: `@ResponseBody` indicates that the method's return value should be written directly to the HTTP response body, often as JSON or XML.

69. What is the role of the `@RequestBody` annotation?

    • Answer: `@RequestBody` indicates that the method parameter should be populated with the data from the HTTP request body.

70. How to handle form submissions with Spring MVC?

    • Answer: Create a form in the view, use a command object in the controller method to receive form data, and use data binding to populate the command object.

71. How to use Spring's `@SessionAttributes` annotation?

    • Answer: `@SessionAttributes` is used to manage attributes in the HTTP session. It allows you to specify model attributes that should be stored in the session.

72. How to handle cookies in Spring MVC?

    • Answer: Use the `HttpServletRequest` and `HttpServletResponse` objects to access and set cookies.

73. How to use Spring's `@CookieValue` annotation?

    • Answer: `@CookieValue` allows you to directly access the value of a cookie in a controller method parameter.

74. How to handle headers in Spring MVC?

    • Answer: Use the `HttpServletRequest` and `HttpServletResponse` objects to access and set HTTP headers.

75. How to configure Spring MVC to use a different port number?

    • Answer: This depends on your deployment environment (e.g., embedded Tomcat in Spring Boot, external web server). You'll typically modify server configuration settings.

76. How to implement caching in Spring MVC?

    • Answer: Use Spring's caching abstraction with annotations like `@Cacheable`, `@CacheEvict`, etc., or use a caching provider like EhCache or Redis.

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