[실습] 게시글 조회 로직 최적화하기 (

JSCODE 박재성

2025-12-06

✅ 게시글 조회 로직 최적화하기

board-service에서 아래 코드 작성하기

1. Board 엔티티에 연관 관계 매핑하기
domain/Board

@Entity
@Table(name = "boards")
public class Board {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long boardId;

  private String title;

  private String content;

  @ManyToOne
  @JoinColumn(name = "user_id", insertable = false, updatable = false) // 조회용
  private User user; 
  
  @Column(name = "user_id")
  private Long userId;

  public Board() {
  }

  public Board(String title, String content, Long userId) {
    this.title = title;
    this.content = content;
    this.userId = userId;
  }

  ...

  public User getUser() {
    return user;
  }
}

 

2. 게시글 조회 로직 수정하기
service/BoardService

@Service
public class BoardService {
  ...
  
  // 연관관계를 활용한 게시글 조회
  public BoardResponseDto getBoard2(Long boardId) {
    Board board = boardRepository.findById(boardId)
        .orElseThrow(() -> new IllegalArgumentException("게시글을 찾을 수 없습니다."));

    // BoardResponseDto 생성
    BoardResponseDto boardResponseDto = new BoardResponseDto(
        board.getBoardId(),
        board.getTitle(),
        board.getContent(),
        new UserDto(
            board.getUser().getUserId(),
            board.getUser().getName()
        )
    );
    
    return boardResponseDto;
  }
  
  // 연관관계를 활용한 게시글 전체 조회
  public List<BoardResponseDto> getBoards2() {
    List<Board> boards = boardRepository.findAll();

    return boards.stream()
        .map(board -> new BoardResponseDto(
            board.getBoardId(),
            board.getTitle(),
            board.getContent(),
            new UserDto(
                board.getUser().getUserId(),
                board.getUser().getName()
            )
        ))
        .toList();
  }
}

 

3. 컨트롤러 로직 바꾸기
controller/BoardController

@RestController
@RequestMapping("/boards")
public class BoardController {
	...

	@GetMapping("/{boardId}")
  public ResponseEntity<BoardResponseDto> getBoard(@PathVariable Long boardId) {
		// BoardResponseDto boardResponseDto = boardService.getBoard(boardId);
    BoardResponseDto boardResponseDto = boardService.getBoard2(boardId);
    return ResponseEntity.ok(boardResponseDto);
  }

  @GetMapping()
  public ResponseEntity<List<BoardResponseDto>> getBoards() {
    // List<BoardResponseDto> boardResponseDtos = boardService.getBoards();
    List<BoardResponseDto> boardResponseDtos = boardService.getBoards2();
    return ResponseEntity.ok(boardResponseDtos);
  }
}

 

4. 서버 다시 실행시키기



 

5. 테스트를 위해 게시글 데이터 2개 넣기





 

6. API 테스트 해보기
1. 특정 게시글 조회하기



 
2. 전체 게시글 조회하기