Understanding the Spring MVC Design Pattern

Spring MVC internally follows the MVC (Model–View–Controller) design pattern. It divides the application into three parts:

• Model – Manages data and business logic.
• View – Represents the front-end (such as JSP pages, Thymeleaf templates). It displays information to the user and collects input.
• Controller – Acts as an intermediary between the View and the Model. It processes user requests, invokes business logic, and sends data back to the View. In Spring MVC, the @Controller and @RequestMapping annotations are mainly responsible for handling HTTP requests.

Key Components in Spring MVC Pattern

1. Client
   • The browser (or any client) sends an HTTP request.
2. DispatcherServlet
   • Known as the Front Controller.
   • This is the entry point of the Spring MVC application.
   • It receives every request from the client and delegates it to the right component.
3. Handler Mapping
   • Determines which Controller should handle the incoming request.
4. Controller
   • Connects the View and the Model.
   • Handles the client request and invokes business logic from the Model.
5. Model
   • Represents the data and business logic of the application.
6. View Resolver
   • Selects the appropriate View (such as JSP, Thymeleaf).
   • In case of a REST controller, the data is returned directly without going through a View.
7. View
   • The final output shown to the user (HTML, JSON, XML, etc.).

Advantages of Spring MVC

• Lightweight – Works with a lightweight servlet container.
• Separation of concerns – Clear separation between front-end and back-end code.
• Loosely coupled – Easy to maintain and extend.
• Team-friendly – Multiple developers can work together efficiently (front-end and back-end separately).