Spring Mvc

Skill: spring-mvc

Type

core

Purpose

Provide server-side rendering using Spring MVC with HTML templates.

When to Use

Use when building applications that render HTML on the server.

Rules

• Use @Controller (NOT @RestController)
• Return template names (not JSON)
• Use Model to pass data to views
• Prefer immutable web model types; use Java record for request/response/view DTOs when mutability is not required
• For @ModelAttribute, prefer constructor binding for dedicated web-binding objects

Architecture

• Controller → handles HTTP requests
• Service → business logic
• Repository → data access

Routing

• Each route returns a full HTML page OR a fragment
• Use clear URL structure (e.g. /users, /users/{id})

Web Model Design (Java 17)

• Preferred: Java record for immutable web-facing objects (request DTOs, response DTOs, view models, form command objects that are constructor-bound)
• Keep web-binding objects separate from domain/persistence objects
• Use mutable classes only when property mutation is required by the use case
• Do NOT use records for JPA entities that require mutable lifecycle behavior

Example

@Controller
@RequestMapping("/users")
public class UserController {

    @GetMapping
    public String list(Model model) {
        model.addAttribute("users", userService.findAll());
        return "users/list";
    }
}

Defaults

• Template folder: src/main/resources/templates
• Naming: feature-based (users/list.html)

Anti-Patterns

• Do NOT return JSON
• Do NOT use @RestController
• Do NOT mix REST and MVC