spring-boot-3

Enforce constructor injection in Spring Boot 3 by defining dependencies as final fields and using a single parameterized constructor, which improves testability and immutability across your service layer.

The best way to manage configuration properties in Spring Boot 3 is using @ConfigurationProperties with validation, which avoids scattered @Value usage and standardizes typed configuration binding.

Structure your Spring Boot 3 REST controller by delegating business logic to a dedicated @Service layer, using @Bean wiring for end-to-end flows and maintaining clear separation of concerns.

You should use @ConfigurationProperties instead of @Value for dependency injection because it provides validated, structured, and typed configuration binding, eliminating scattered @Value annotations and maintenance challenges.

Spring Boot 3 works best with constructor injection by default for bean wiring, as it enforces immutability and improves testability without requiring additional annotations for single-constructor classes.

You need to add validation to Spring Boot 3 configuration properties when binding external configurations via @ConfigurationProperties, ensuring invalid or missing values fail fast during application startup.