Mastering Spring MVC: Core Concepts, Components, and Annotations Explained

Spring MVC is a lightweight Java web framework that implements the Model‑View‑Controller pattern, separating concerns to simplify development and improve maintainability.

Advantages

Supports multiple view technologies beyond JSP.

Integrates with the Spring IoC container and AOP.

Clear role distribution: DispatcherServlet, HandlerMapping, HandlerAdapter, ViewResolver.

Flexible request‑resource mapping strategies.

Core components

DispatcherServlet – front‑controller that receives all HTTP requests.

HandlerMapping – finds the appropriate controller based on the URL.

HandlerAdapter – invokes the controller.

Controller (Handler) – contains business logic; should be stateless to avoid thread‑safety issues.

ViewResolver – resolves logical view names to actual view implementations (JSP, Freemarker, etc.).

View – the rendered page.

Request processing flow

User sends a request to DispatcherServlet. DispatcherServlet obtains a Handler via HandlerMapping. DispatcherServlet calls the appropriate HandlerAdapter.

The Handler executes and returns a ModelAndView. HandlerAdapter passes the ModelAndView back to DispatcherServlet. DispatcherServlet forwards the model to ViewResolver, which selects the concrete View.

The view renders the model data and the response is sent to the client.

Transaction management

Spring provides programmatic (using TransactionTemplate) and declarative transaction management (using @Transactional with AOP). Declarative transactions support propagation behaviors (REQUIRED, REQUIRES_NEW, SUPPORTS, etc.) and isolation levels (READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE, etc.).

Common Spring MVC annotations @Controller – marks a class as a Spring MVC controller. @RequestMapping – maps URLs, HTTP methods, parameters, headers, consumes/produces media types. @PathVariable – binds URI template variables to method parameters. @RequestParam – binds request parameters to method arguments. @RequestBody – binds the request body (e.g., JSON) to a Java object. @ResponseBody – writes the return value directly to the HTTP response. @Autowired and @Resource – inject beans; @Autowired defaults to by‑type, @Resource defaults to by‑name. @ModelAttribute and @SessionAttributes – prepare model data before handler execution and store selected attributes in the HTTP session.

These annotations enable concise, type‑safe request handling and seamless integration with Spring’s IoC container.

Component scanning

Using <context:component-scan> with optional include-filter and exclude-filter allows selective registration of @Component, @Controller, @Service, and @Repository beans.

Comparison with Struts2

Spring MVC uses DispatcherServlet as the front controller; Struts2 uses a filter.

Spring MVC binds request data to method parameters (thread‑safe, singleton possible); Struts2 binds to action properties (prototype scope).

Spring MVC integrates naturally with the Spring ecosystem; Struts2 requires separate integration.