@Controller

Spring MVC Web Controller

`@Controller` registers web controllers that return view names rendered by view resolvers.

Server-Side Template Rendering:

In traditional Web applications (built with Thymeleaf, FreeMarker, or JSP), @Controller methods return String view template names. Spring MVC's ViewResolver maps the returned string to a physical template file in resources/templates/.

• Model Injection: Inject org.springframework.ui.Model into controller methods to pass data attributes to HTML views.
• REST API Conversion: To return raw JSON instead of HTML view templates, combine @Controller with @ResponseBody or use @RestController.

Production Code Example:

package com.anujsingh.digitalguru.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class WebController {
    @GetMapping("/home")
    public String home() { return "home"; }
}

Key Architectural Concepts & Best Practices:

When working with @Controller in enterprise Spring Boot applications, keep these key architectural guidelines in mind:

• Separation of Concerns: Maintain a strict boundary between HTTP endpoints, service logic, and database persistence layers.
• Framework Conventions: Rely on Spring Boot auto-configuration defaults whenever possible, overriding settings only via application.yml or @Configuration classes when customized behavior is required.
• Production Monitoring & Reliability: Ensure proper exception handling, thread-safety, and resource cleanup to prevent memory leaks and unexpected runtime downtime.
• Developer Ergonomics: Write clean, self-documenting code with modern Java features (Records, Lambdas, Streams) to simplify code reviews and maintenance.

Summary Takeaway:

Mastering @Controller ensures that your Java & Spring Boot backend microservices remain maintainable, secure, and compliant with modern enterprise software engineering standards.