Spring Boot Best Practices

Priority: P0

Implementation Guidelines

Dependency Injection (DI)

• Constructor Injection: ALWAYS use constructor injection (via @RequiredArgsConstructor) for immutability.
• Final Fields: Mark all dependencies as final.
• Avoid @Autowired: Do not use field injection. It hides dependencies.

Configuration

• Type-Safe Config: Use @ConfigurationProperties with Records instead of @Value.
• Validation: Combine with @Validated and Jakarta constraints (@NotNull) to fail fast.
• Externalization: Follow strict precedence (Env vars > Config files).

Observability & Logging

• SLF4J: Use @Slf4j. NEVER use System.out.
• Structured Logging: Log arguments (log.info("id: {}", id)), not concatenated strings.

Anti-Patterns

• Field Injection: **No @Autowired on fields**: Use constructor injection.
• Mutable Components: **No Setters**: Use final fields.
• Manual Bean Lookup: **No context.getBean()**: Inject dependencies.
• Swallowed Exceptions: **No log-and-swallow**: Rethrow or handle cleanly.

References

• Implementation Examples