[Spring] 페이지네이션 1페이지부터 시작하기

1. 페이지네이션 1페이지부터 시작하기

    @GetMapping("/board/listings")
    public String listings(HttpServletRequest request,@RequestParam(defaultValue = "1")int page) {
        List<BoardResponse.boardAndUserDTO> responseDTO = boardRepository.findByBoardtbAndUsertb(page);
        // 회원 테이블에서 개인 기업 구분
List<BoardResponse.boardAndUserDTO> employerList = new ArrayList<>();
        for (BoardResponse.boardAndUserDTO dto : responseDTO) {
            if (dto.isEmployer()) {
                employerList.add(dto);
            }
        }
        request.setAttribute("employerList", employerList);


        int currentPage = page;
        int nextPage = currentPage + 1;
        int prevPage = currentPage - 1;

        request.setAttribute("nextPage", nextPage);
        request.setAttribute("prevPage", prevPage);


        boolean first = (currentPage == 1 ? true : false);
        request.setAttribute("first", first);

        int totalPage = boardRepository.countIsEmployerTrue();

        int totalCount = (totalPage % 10 == 0) ? (totalPage / 10) : (totalPage / 10 + 1);
        boolean last = (currentPage == totalCount);
        List<Integer> numberList = new ArrayList<>();
        int allPage = totalCount ;

        for (int i = 1; i <= allPage; i++) {
            numberList.add(i);
            request.setAttribute("numberList", numberList);
        }

        request.setAttribute("last", last);

        return "/board/listings";
        }

    public List<BoardResponse.boardAndUserDTO> findByBoardtbAndUsertb(int page){
        final int COUNT = 10;
        int value = (page - 1) * COUNT;
        String q = """
            SELECT b.id, b.user_id, b.title, b.content, b.field, b.position, b.salary, b.opening_date, b.closing_date, b.created_at, u.username, u.address, u.is_employer, u.business_name FROM board_tb b INNER JOIN user_tb u ON b.user_id = u.id WHERE u.is_employer = true ORDER BY b.id DESC LIMIT ?,?;               
                    """;
				// 개인 기업 유무 확인을 위해 쿼리에 true false 포함되어있음
        Query query = entityManager.createNativeQuery(q);
        query.setParameter(1,value);
        query.setParameter(2,COUNT);
        List<Object[]> results = query.getResultList();
        List<BoardResponse.boardAndUserDTO> responseDTO = new ArrayList<>();

        for(Object[] result :results){

            BoardResponse.boardAndUserDTO dto = new BoardResponse.boardAndUserDTO();
            dto.setId((Integer) result[0]);
            dto.setUserId((Integer) result[1]);
            dto.setTitle((String) result[2]);
            dto.setContent((String) result[3]);
            dto.setField((String) result[4]);
            dto.setPosition((String) result[5]);
            dto.setSalary((String) result[6]);
            dto.setOpeningDate((Timestamp) result[7]);
            dto.setClosingDate((Timestamp) result[8]);
            dto.setCreatedAt((Timestamp) result[9]);
            dto.setUsername((String) result[10]);
            dto.setAddress((String) result[11]);
            dto.setEmployer((boolean) result[12]);
            dto.setBusinessName((String) result[13]);



            responseDTO.add(dto);
        }
        return responseDTO;

    }

    public int countIsEmployerTrue() {
        String q = """
                SELECT COUNT(*) FROM board_tb b INNER JOIN user_tb u ON b.user_id = u.id WHERE u.is_employer = true;
                """;
        Query query = entityManager.createNativeQuery(q);
        Long count = (Long) query.getSingleResult();
        return count.intValue();

    }

    <div class="d-flex justify-content-center">
        <ul class="pagination">
            <li class="page-item {{#first}}disabled{{/first}}"><a class="page-link" href="?page={{prevPage}}">Previous</a></li>
            {{#numberList}}
                <li class="page-item"><a class="page-link" href="?page={{.}}">{{.}}</a></li>
            {{/numberList}}
            <li class="page-item {{#last}}disabled{{/last}}"><a class="page-link" href="?page={{nextPage}}">Next</a></li>
        </ul>
    </div>

2. 페이지네이션 모듈화

    @GetMapping("/board/listings")
    public String listings(HttpServletRequest request,@RequestParam(defaultValue = "1")int page) {
        List<BoardResponse.boardAndUserDTO> responseDTO = boardRepository.findByBoardtbAndUsertb(page);
        List<BoardResponse.boardAndUserDTO> employerList = new ArrayList<>();
        for (BoardResponse.boardAndUserDTO dto : responseDTO) {
            if (dto.isEmployer()) {
                employerList.add(dto);
            }
        }
        request.setAttribute("employerList", employerList);
        // 페이지네이션 모듈
        int totalPage = boardRepository.countIsEmployerTrue(); //DB에서 게시글 수 조회
        PagingUtil paginationHelper = new PagingUtil(totalPage, page);

        request.setAttribute("nextPage", paginationHelper.getNextPage());
        request.setAttribute("prevPage", paginationHelper.getPrevPage());
        request.setAttribute("first", paginationHelper.isFirst());
        request.setAttribute("last", paginationHelper.isLast());
        request.setAttribute("numberList", paginationHelper.getNumberList());

        return "/board/listings";
        }

package shop.mtcoding.projectjobplan._core;

import lombok.RequiredArgsConstructor;

import java.util.ArrayList;
import java.util.List;

@RequiredArgsConstructor
public class PagingUtil {
    private int totalCount;
    private int currentPage;

    public PagingUtil(int totalCount, int currentPage) {
        this.totalCount = totalCount;
        this.currentPage = currentPage;
    }
    public int getNextPage() {
        return this.currentPage + 1;
    }

    public int getPrevPage() {
        return this.currentPage - 1;
    }

    public boolean isFirst() {
        return this.currentPage == 1;
    }

    public int getTotalPageCount() {
        return (this.totalCount % 10 == 0) ? (this.totalCount / 10) : (this.totalCount / 10 + 1);
    }

    public boolean isLast() {
        return this.currentPage == getTotalPageCount();
    }

    public List<Integer> getNumberList() {
        List<Integer> numberList = new ArrayList<>();
        for (int i = 1; i <= getTotalPageCount(); i++) {
            numberList.add(i);
        }
        return numberList;
    }

}