Springboot Patterns

# Spring Boot Development Patterns

Spring Boot architecture and API patterns for scalable, production-grade services.

## When to Activate

- Building REST APIs with Spring MVC or WebFlux
- Structuring controller → service → repository layers
- Configuring Spring Data JPA, caching, or async processing
- Adding validation, exception handling, or pagination
- Setting up profiles for dev/staging/production environments
- Implementing event-driven patterns with Spring Events or Kafka

## 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)