spring-boot-web-api

Spring Boot 4 REST APIs use @Valid annotations on controller methods to validate request bodies against Bean Validation 3.1 constraints. Immutable DTOs via records define validation rules, and a global exception handler catches violations to return consistent RFC 9457 ProblemDetail error responses with typed error details and unique error URIs.

Centralized exception handling with ProblemDetail implements RFC 9457 standards for error responses. Configure a global @ControllerAdvice handler to catch validation and business exceptions, returning structured error details with unique URIs, HTTP status codes, and machine-readable error types for all REST endpoints.

Yes. Spring Boot 4 supports reactive REST endpoints via WebFlux with identical validation using @Valid, Bean Validation 3.1, immutable DTOs, and centralized ProblemDetail-based exception handling. Jackson 3 configuration works with both Spring MVC and WebFlux for content negotiation.

Spring Boot 4 supports native API versioning directly in request mappings, allowing multiple API versions to coexist. Configure version strategies in controller mappings to route requests to appropriate handlers without altering endpoint URLs or requiring separate codebases.

Spring Boot 4 includes Jackson 3 configuration by default for REST controllers and WebFlux endpoints. Custom content negotiation and serialization rules can be configured globally, but basic REST serialization of DTOs and error responses works out of the box.

Controllers should delegate business logic to service layers and data access to repositories, keeping controllers thin. This separation makes validation at the DTO boundary, exception handling in global advisors, and business rules in services testable and maintainable.