SPRING MVC – SLAVICO

Spring MVC (Model-View-Controller)

Overview: Spring MVC is a web application framework that is part of the broader Spring Framework. It follows the Model-View-Controller (MVC) architectural pattern, which separates an application into three main components: Model (data and business logic), View (user interface), and Controller (handles requests and responses). Spring MVC provides a powerful and flexible mechanism for building web-based applications and RESTful services in Java.

By leveraging Spring’s core features such as dependency injection, aspect-oriented programming, and robust configuration options, Spring MVC enables developers to build scalable and maintainable web applications with ease.

Purpose and Architecture:

Spring MVC simplifies the development of web applications by:

Decoupling business logic from presentation logic.
Handling HTTP requests through annotated controllers.
Mapping requests to handler methods.
Providing multiple view rendering options (JSP, Thymeleaf, PDF, JSON, etc.).

The MVC architecture enhances maintainability and modularity by clearly separating application concerns.

Spring MVC Request Flow:

Client sends a request (e.g., via browser).
DispatcherServlet receives the request and acts as the front controller.
HandlerMapping determines which controller method to call.
Controller processes the request and returns a ModelAndView object.
ViewResolver identifies the appropriate view template.
View renders the response and sends it back to the client.

Key Components:

DispatcherServlet: Central controller to dispatch requests to appropriate handlers.
Controller: Handles incoming requests and binds them to business logic.
Model: Holds application data.
View: Renders output using technologies like JSP, Thymeleaf, or HTML.
HandlerMapping: Maps URLs to controller methods.
ViewResolver: Resolves the name of the view into an actual view page.

Example – Basic Spring MVC Controller:

@Controller
public class HelloController {

    @RequestMapping("/hello")
    public String sayHello(Model model) {
        model.addAttribute("message", "Hello, Spring MVC!");
        return "hello"; // Returns the view name
    }
}

hello.jsp (View):

<html>
  <body>
    <h2>${message}</h2>
  </body>
</html>

Annotations Used in Spring MVC:

@Controller – Declares a class as a controller.
@RequestMapping – Maps URLs to controller methods.
@GetMapping, @PostMapping – Specialized versions of @RequestMapping.
@ModelAttribute – Binds method parameters to model attributes.
@ResponseBody – Sends the return value directly to the response body (used in REST).
@RestController – Combines @Controller and @ResponseBody for REST APIs.

Advantages of Spring MVC:

Clean separation of concerns (MVC)
Flexible and powerful URL routing
Annotation-based configuration
Integration with Spring ecosystem
RESTful API support out of the box
Support for multiple view technologies
Highly testable architecture

Limitations:

Complex configuration in traditional Spring MVC (before Spring Boot)
Verbose XML configurations (mitigated with annotations and Java config)
Steep learning curve for beginners

Use Cases:

Dynamic web applications
Enterprise portals and intranet systems
RESTful API development
Admin dashboards and backend interfaces
Hybrid applications combining server-side and client-side rendering

Spring MVC vs Traditional Java Web Development:

Feature	Spring MVC	Traditional Servlets/JSP
Configuration	Declarative (annotations, Java config)	Manual and XML-based
Reusability & Testability	High	Low
RESTful Support	Built-in	Requires custom logic
Scalability	High modularity	Harder to manage growth

Conclusion:

Spring MVC is a mature and robust web framework that has become a cornerstone in Java web development. Its clean architecture, ease of integration, and flexibility make it a preferred choice for building both traditional web applications and modern RESTful services. When paired with Spring Boot, it enables rapid development and deployment of scalable web solutions with minimal configuration.