Spring Boot Best Practices
Priority: P0 (CRITICAL)
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
- Error Handling: Implement
@ControllerAdvice and ProblemDetails (RFC 7807) for standardized error responses.
- Logging: Use
SLF4J with @Slf4j. Implement Structured Logging by logging arguments (log.info("id: {}", id)).
- Tooling: Mandate
Spotless or Checkstyle for code formatting. Use sdkman to manage JDK 21+ versions.
Anti-Patterns
- No @Autowired on fields: Use constructor injection via @RequiredArgsConstructor.
- No Setters on dependencies: Declare all injected fields as final.
- No context.getBean(): Inject dependencies via constructor DI.
- No log-and-swallow: Rethrow or handle exceptions explicitly.
References
