Spring Boot Best Practices

Priority: P0

Implementation Guidelines

Dependency Injection (DI)

• Constructor Injection: ALWAYS use Constructor Injection for immutability. Use @RequiredArgsConstructor (Lombok) to reduce boilerplate. Mark all dependencies as final.
• Avoid @Autowired: NEVER use field injection. It prevents unit testing without Spring context and hides dependencies.

Configuration & Data

• Type-Safe Config: Use @ConfigurationProperties with Records (Java 17+) instead of @Value. Use Spring profile-specific files (e.g., application-dev.yml, application-prod.yml) and set active profile via SPRING_PROFILES_ACTIVE. Never hardcode secret values in properties files.
• Validation: Combine with @Validated and Jakarta Bean Validation (@NotNull, @NotEmpty) to fail fast at startup. Use application.yaml for structured configuration.
• DTOs: Use records as immutable DTOs to reduce boilerplate and ensure thread safety. Handle empty values with Optional to avoid NullPointerException.

Observability & Quality