Spring MVC Framework Concept for Interview
Spring MVC (Model/View/Controller) is a framework within the Spring framework that provides comprehensive support for creating web applications. It follows the Model/View/Controller design pattern, which helps in separating the different aspects of the application, such as input logic, business logic, and UI logic, while providing a loose coupling between these elements.
Key Components of Spring MVC
1. Dispatcher Servlet:
Acts as the front controller for Spring MVC applications.
Dispatches requests to appropriate handlers based on the configuration.
2. Controller:
Handles user requests and returns a Model and View object that contains both the model data and the view name.
Annotated with @Controller or @RestController (for RESTful web services).
3. Model:
Represents the application's data.
Typically consists of POJOs (Plain Old Java Objects) that are manipulated by the controllers.
4. View:
Responsible for rendering the UI.
Can be JSP, Thymeleaf, FreeMarker, or other templating engines.
The view name returned by the controller is resolved by a ViewResolver to render the appropriate view.
5. ModelAndView:
A holder for both Model and View in the web MVC framework.
Used to pass model data to the view.
6. HandlerMapping:
Maps incoming web requests to appropriate handler methods.
Different implementations available, like RequestMappingHandlerMapping, which maps requests to @RequestMapping annotated methods.
7. ViewResolver:
Resolves the logical view name returned by the controller to a specific view implementation.
Commonly used implementations include InternalResourceViewResolver for JSP and ThymeleafViewResolver for Thymeleaf templates.
Commonly asked interview questions related to Spring MVC
1. What is Spring MVC? Explain its architecture.
Spring MVC is a module within the Spring Framework that follows the ModelViewController (MVC) design pattern. Its architecture consists of the DispatcherServlet, Controllers, Models, Views, ViewResolver, and HandlerMapping.
2. What is DispatcherServlet and its role in Spring MVC?
The DispatcherServlet is the front controller in Spring MVC that handles all incoming web requests, delegates them to appropriate controllers, and manages the overall request handling process.
3. How do you configure Spring MVC in a web application?
Spring MVC can be configured using Javabased configuration (@EnableWebMvc and a configuration class) or XMLbased configuration (defining DispatcherServlet in web.xml and setting up the application context).
4. What is the role of the @Controller annotation in Spring MVC?
The @Controller annotation is used to define a class as a Spring MVC controller that handles web requests. Methods within this class can handle requests using @RequestMapping.
5. What is the difference between @Controller and @RestController?
@Controller is used for traditional web applications where the view is returned, whereas @RestController is a convenience annotation that combines @Controller and @ResponseBody, making it suitable for RESTful web services by returning the response directly as JSON or XML.
6. Explain the role of @RequestMapping annotation.
@RequestMapping is used to map web requests to specific handler methods in a controller. It can be applied at the class level and method level to specify the URL pattern, HTTP method, and other request parameters.
7. How does Spring MVC handle form submission?
Spring MVC handles form submission using a combination of form tags in the view, a formbacking object (model attribute), and controller methods annotated with @PostMapping or @RequestMapping to handle form data.
8. What is the use of ModelAndView in Spring MVC?
ModelAndView is a holder for both model data and view name in a Spring MVC application. It is used to pass model data to the view for rendering.
9. How do you validate form data in Spring MVC?
Form data validation can be performed using JSR303/JSR380 annotations (e.g., @NotNull, @Size) in the model class and the @Valid annotation in the controller method. BindingResult is used to check for validation errors.
10. What is the purpose of @ExceptionHandler in Spring MVC?
@ExceptionHandler is used to define methods in a controller or a global exception handling class to handle specific exceptions thrown during request processing.
11. How can you handle file uploads in Spring MVC?
File uploads can be handled using MultipartFile in the controller, and configuring MultipartResolver in the Spring context.
12. How do you configure an interceptor in Spring MVC?
Interceptors can be configured by implementing the HandlerInterceptor interface and registering it in the WebMvcConfigurer configuration class using addInterceptors method.
13. What are some best practices for developing Spring MVC applications?
Some best practices include using RESTful principles, proper exception handling, using Spring Security for authentication and authorization, efficient database access with Spring Data, and optimizing view rendering.
14. How can you improve the performance of a Spring MVC application?
Performance can be improved by using caching (e.g., @Cacheable), optimizing SQL queries, using a Content Delivery Network (CDN) for static resources, minimizing the use of session, and tuning the web server configuration.
Spring MVC application Real World Scenarios Question
15. How would you handle a scenario where you need to support multiple view technologies in a Spring MVC application?
This can be achieved by configuring multiple ViewResolvers in the Spring context, each resolving a different view technology (e.g., JSP, Thymeleaf, FreeMarker).
16. How do you test Spring MVC applications?
Testing Spring MVC applications can be done using tools like JUnit and Mockito for unit tests, and Spring's MockMvc for integration tests.