springboot-patterns

# Spring Boot Development Patterns Spring Boot architecture and API patterns for scalable, production-grade services. ## REST API Structure ```java @RestController @RequestMapping("/api/markets") @Validated class MarketController { private final MarketService marketService; MarketController(MarketService marketService) { this.marketService = marketService; } @GetMapping ResponseEntity<Page<MarketResponse>> list( @RequestParam(defaultValue = "0") int page, @RequestParam(defaultValue = "20") int size) { Page<Market> markets = marketService.list(PageRequest.of(page, size)); return ResponseEntity.ok(markets.map(MarketResponse::from)); } @PostMapping ResponseEntity<MarketResponse> create(@Valid @RequestBody CreateMarketRequest request) { Market market = marketService.create(request); return ResponseEntity.status(HttpStatus.CREATED).body(MarketResponse.from(market)); } } ``` ## Repository Pattern (Spring Data JPA) ```java public interface MarketRepository extends JpaRepository<MarketEntity, Long> { @Query("select m from MarketEntity m where m.status = :status order by m.volume desc") List<MarketEntity> findActive(@Param("status") MarketStatus status, Pageable pageable); } ``` ## Service Layer with Transactions ```java @Service public class MarketService { private final MarketRepository repo; public MarketService(MarketRepository repo) { this.repo = repo; } ...