220513 Spring - Chapter 4. MyBatis로 게시판 만들기(Part.5)

댓글 기능 구현 - DAO와 Service의 작성

 

1. 댓글 기능 구현 순서

 

1) DB테이블 생성

2) Mapper XML 작성 (SQL문으로 CRUD를 작성)

3) DAO 작성 & 테스트

4) Service 작성 & 테스트

5) 컨트롤러 작성 & 테스트

6) HTML, CSS, JS, JQuery

 

 

1) DB테이블 생성

MySQL에서 DB 테이블을 생성한다.

 

각 항목은 다음과 같다

cno : 댓글 번호

bno : 글 번호

pcno : 대댓글 번호

comment : 댓글 내용

commenter : 댓글 남긴 사람

reg_date : 댓글 등록 날짜

up_date : 댓글 수정 날짜

 

 

 

CommentDto를 만든다.

 

package com.fastcampus.ch6.domain;

import java.util.Date;
import java.util.Objects;

public class CommentDto {
    private Integer cno;
    private Integer bno;
    private Integer pcno;
    private String comment;
    private String commenter;
    private Date reg_date;
    private Date up_date;

    public CommentDto() {}

    public CommentDto(Integer bno, Integer pcno, String comment, String commenter) {
        this.bno = bno;
        this.pcno = pcno;
        this.comment = comment;
        this.commenter = commenter;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        CommentDto that = (CommentDto) o;
        return Objects.equals(cno, that.cno) && Objects.equals(bno, that.bno) && Objects.equals(pcno, that.pcno) && Objects.equals(comment, that.comment) && Objects.equals(commenter, that.commenter);
    }

    @Override
    public String toString() {
        return "CommentDto{" +
                "cno=" + cno +
                ", bno=" + bno +
                ", pcno=" + pcno +
                ", comment='" + comment + '\'' +
                ", commenter='" + commenter + '\'' +
                ", reg_date=" + reg_date +
                ", up_date=" + up_date +
                '}';
    }

    @Override
    public int hashCode() {
        return Objects.hash(cno, bno, pcno, comment, commenter);
    }

    public Integer getCno() {
        return cno;
    }

    public void setCno(Integer cno) {
        this.cno = cno;
    }

    public Integer getBno() {
        return bno;
    }

    public void setBno(Integer bno) {
        this.bno = bno;
    }

    public Integer getPcno() {
        return pcno;
    }

    public void setPcno(Integer pcno) {
        this.pcno = pcno;
    }

    public String getComment() {
        return comment;
    }

    public void setComment(String comment) {
        this.comment = comment;
    }

    public String getCommenter() {
        return commenter;
    }

    public void setCommenter(String commenter) {
        this.commenter = commenter;
    }

    public Date getReg_date() {
        return reg_date;
    }

    public void setReg_date(Date reg_date) {
        this.reg_date = reg_date;
    }

    public Date getUp_date() {
        return up_date;
    }

    public void setUp_date(Date up_date) {
        this.up_date = up_date;
    }
}

 

 

2) Mapper XML 작성 (SQL문으로 CRUD를 작성)

새로 commentMapper.xml 파일을 생성하고 쿼리문을 작성한다.

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.fastcampus.ch4.dao.CommentMapper">
    <delete id="deleteAll" parameterType="int">
        DELETE FROM comment
        WHERE  bno = #{bno}
    </delete>

    <select id="count" parameterType="int" resultType="int">
        SELECT count(*) FROM comment
        WHERE  bno = #{bno}
    </select>

    <delete id="delete" parameterType="map">
        DELETE FROM comment WHERE cno = #{cno} AND commenter = #{commenter}
    </delete>

    <insert id="insert" parameterType="CommentDto">
        INSERT INTO comment
            (bno, pcno, comment, commenter, reg_date, up_date)
        VALUES
            (#{bno}, #{pcno}, #{comment}, #{commenter}, now(), now())
    </insert>

    <select id="selectAll" parameterType="int" resultType="CommentDto">
        SELECT cno, bno, pcno, comment, commenter, reg_date, up_date
        FROM comment
        WHERE bno = #{bno}
        ORDER BY reg_date ASC, cno ASC
    </select>

    <select id="select" parameterType="int" resultType="CommentDto">
        SELECT cno, bno, pcno, comment, commenter, reg_date, up_date
        FROM comment
        WHERE cno = #{cno}
    </select>

    <update id="update" parameterType="CommentDto">
        UPDATE comment
        SET comment = #{comment}
          , up_date = now()
        WHERE cno = #{cno} and commenter = #{commenter}
    </update>
</mapper>

( src/resources 경로의 mybatis-config.xml 파일에 CommentDto에 대한 alias를 추가해줘야 parameterType에서 CommentDto를 간편하게 사용할 수 있다)

 

 

 

3) DAO 작성 & 테스트

package com.fastcampus.ch4.dao;

import com.fastcampus.ch4.domain.BoardDto;
import com.fastcampus.ch4.domain.SearchCondition;
import org.apache.ibatis.session.SqlSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Repository
public class BoardDaoImpl implements BoardDao {
    @Autowired
    private SqlSession session;

    private static String namespace = "com.fastcampus.ch4.dao.BoardMapper.";

    @Override
    public int count() throws Exception {
        return session.selectOne(namespace+"count");
    } // T selectOne(String statement)

    @Override
    public int deleteAll() {
        return session.delete(namespace+"deleteAll");
    } // int delete(String statement)

    @Override
    public int delete(Integer bno, String writer) throws Exception {
        Map map = new HashMap();
        map.put("bno", bno);
        map.put("writer", writer);
        return session.delete(namespace+"delete", map);
    } // int delete(String statement, Object parameter)

    @Override
    public int insert(BoardDto dto) throws Exception {
        return session.insert(namespace+"insert", dto);
    } // int insert(String statement, Object parameter)

    @Override
    public List<BoardDto> selectAll() throws Exception {
        return session.selectList(namespace+"selectAll");
    } // List<E> selectList(String statement)

    @Override
    public BoardDto select(Integer bno) throws Exception {
        return session.selectOne(namespace + "select", bno);
    } // T selectOne(String statement, Object parameter)

    @Override
    public List<BoardDto> selectPage(Map map) throws Exception {
        return session.selectList(namespace+"selectPage", map);
    } // List<E> selectList(String statement, Object parameter)

    @Override
    public int update(BoardDto dto) throws Exception {
        return session.update(namespace+"update", dto);
    } // int update(String statement, Object parameter)

    @Override
    public int increaseViewCnt(Integer bno) throws Exception {
        return session.update(namespace+"increaseViewCnt", bno);
    } // int update(String statement, Object parameter)

    @Override
    public int searchResultCnt(SearchCondition sc) throws Exception {
//        System.out.println("sc in searchResultCnt() = " + sc);
//        System.out.println("session = " + session);
        return session.selectOne(namespace+"searchResultCnt", sc);
} // T selectOne(String statement, Object parameter)

    @Override
    public List<BoardDto> searchSelectPage(SearchCondition sc) throws Exception {
        return session.selectList(namespace+"searchSelectPage", sc);
    } // List<E> selectList(String statement, Object parameter)

    @Override
    public int updateCommentCnt(Integer bno, int cnt) throws Exception {
        Map map = new HashMap();
        map.put("bno", bno);
        map.put("cnt", cnt);

        return session.update(namespace+"updateCommentCnt", map);
    }

}

기존에 작성했던 BoardDaoImple에 updateCommentCnt 메소드 하나를 추가했다

board 테이블에 댓글수를 반영해야 하기 때문이다.

 

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Repository
public class CommentDaoImpl implements CommentDao {
    @Autowired
    private SqlSession session;
    private static String namespace = "com.fastcampus.ch4.dao.CommentMapper.";

    @Override
    public int deleteAll(Integer bno) throws Exception {
        return session.delete(namespace+"deleteAll", bno);
    }

    @Override
    public int count(Integer bno) throws Exception {
        return session.selectOne(namespace+"count", bno);
    }

    @Override
    public int delete(Integer cno, String commenter) throws Exception {
        Map map = new HashMap();
        map.put("cno", cno);
        map.put("commenter", commenter);
        return session.delete(namespace+"delete", map);
    }

    @Override
    public int insert(CommentDto dto) throws Exception {
        return session.insert(namespace+"insert", dto);
    }

    @Override
    public List<CommentDto> selectAll(Integer bno) throws Exception {
        return session.selectList(namespace+"selectAll", bno);
    }

    @Override
    public CommentDto select(Integer cno) throws Exception {
        return session.selectOne(namespace+"select", cno);
    }

    @Override
    public int update(CommentDto dto) throws Exception {
        return session.update(namespace+"update", dto);
    }
}

 

CommentDao를 만들어준다.

 

 

 

package com.fastcampus.ch4.dao;

import com.fastcampus.ch4.domain.*;
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.test.context.*;
import org.springframework.test.context.junit4.*;

import java.util.*;

import static org.junit.Assert.*;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"file:src/main/webapp/WEB-INF/spring/root-context.xml"})
public class CommentDaoImplTest {
    @Autowired
    CommentDao commentDao;

    @Test
    public void count() throws Exception {
        commentDao.deleteAll(1);
        assertTrue(commentDao.count(1)==0);
    }

    @Test
    public void delete() throws Exception {
        commentDao.deleteAll(1);
        CommentDto commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==1);
    }

    @Test
    public void insert() throws Exception {
        commentDao.deleteAll(1);
        CommentDto commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==1);

        commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==2);
    }

    @Test
    public void selectAll() throws Exception {
        commentDao.deleteAll(1);
        CommentDto commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==1);

        List<CommentDto> list = commentDao.selectAll(1);
        assertTrue(list.size()==1);

        commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==2);

        list = commentDao.selectAll(1);
        assertTrue(list.size()==2);
    }

    @Test
    public void select() throws Exception {
        commentDao.deleteAll(1);
        CommentDto commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==1);

        List<CommentDto> list = commentDao.selectAll(1);
        String comment = list.get(0).getComment();
        String commenter = list.get(0).getCommenter();
        assertTrue(comment.equals(commentDto.getComment()));
        assertTrue(commenter.equals(commentDto.getCommenter()));
    }

    @Test
    public void update() throws Exception {
        commentDao.deleteAll(1);
        CommentDto commentDto = new CommentDto(1, 0, "comment", "asdf");
        assertTrue(commentDao.insert(commentDto)==1);
        assertTrue(commentDao.count(1)==1);

        List<CommentDto> list = commentDao.selectAll(1);
        commentDto.setCno(list.get(0).getCno());
        commentDto.setComment("comment2");
        assertTrue(commentDao.update(commentDto)==1);

        list = commentDao.selectAll(1);
        String comment = list.get(0).getComment();
        String commenter = list.get(0).getCommenter();
        assertTrue(comment.equals(commentDto.getComment()));
        assertTrue(commenter.equals(commentDto.getCommenter()));
    }
}

만든 CommentDaoImpl을 테스트 하였다.

 

 

4) Service 작성 & 테스트

package com.fastcampus.ch4.service;

import com.fastcampus.ch4.dao.*;
import com.fastcampus.ch4.domain.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.stereotype.*;
import org.springframework.transaction.annotation.*;

import java.util.*;

@Service
public class CommentServiceImpl implements CommentService {
//    @Autowired
    BoardDao boardDao;
//    @Autowired
    CommentDao commentDao;

    @Autowired
    public CommentServiceImpl(CommentDao commentDao, BoardDao boardDao) {
        this.commentDao = commentDao;
        this.boardDao = boardDao;
    } // 인스턴스 주입보다 생성자 주입을 권장함(컴파일 단계에서 오류를 알 수 있으므로 실수가 적어짐)

    @Override
    public int getCount(Integer bno) throws Exception {
        return commentDao.count(bno);
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public int remove(Integer cno, Integer bno, String commenter) throws Exception {
        int rowCnt = boardDao.updateCommentCnt(bno, -1);
        System.out.println("updateCommentCnt - rowCnt = " + rowCnt);
//        throw new Exception("test");
        rowCnt = commentDao.delete(cno, commenter);
        System.out.println("rowCnt = " + rowCnt);
        return rowCnt;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public int write(CommentDto commentDto) throws Exception {
        boardDao.updateCommentCnt(commentDto.getBno(), 1);
//                throw new Exception("test");
        return commentDao.insert(commentDto);
    }

    @Override
    public List<CommentDto> getList(Integer bno) throws Exception {
//        throw new Exception("test");
        return commentDao.selectAll(bno);
    }

    @Override
    public CommentDto read(Integer cno) throws Exception {
        return commentDao.select(cno);
    }

    @Override
    public int modify(CommentDto commentDto) throws Exception {
        return commentDao.update(commentDto);
    }
}

Service도 만들어주었다.

이번에는 생성자를 이용하여 BoardDao와 CommentDao를 주입받았다.

인스턴스 주입을 하면, 실수를 했을 때 컴파일 단계에서 오류를 찾아내기 힘들어지기 때문에

컴파일 단계에서 오류를 잡을 수 있는 생성자로 객체를 주입받는 것이 좋다.

 

package com.fastcampus.ch4.service;

import com.fastcampus.ch4.dao.*;
import com.fastcampus.ch4.domain.*;
import org.junit.*;
import org.junit.runner.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.test.context.*;
import org.springframework.test.context.junit4.*;

import java.util.*;

import static org.junit.Assert.*;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"file:src/main/webapp/WEB-INF/spring/root-context.xml"})
public class CommentServiceImplTest {
    @Autowired
    CommentService commentService;
    @Autowired
    CommentDao commentDao;
    @Autowired
    BoardDao boardDao;

    @Test
    public void remove() throws Exception {
        boardDao.deleteAll();

        BoardDto boardDto = new BoardDto("hello", "hello", "asdf");
        assertTrue(boardDao.insert(boardDto) == 1);
        Integer bno = boardDao.selectAll().get(0).getBno();
        System.out.println("bno = " + bno);

        commentDao.deleteAll(bno);
        CommentDto commentDto = new CommentDto(bno,0,"hi","qwer");

        assertTrue(boardDao.select(bno).getComment_cnt() == 0);
        assertTrue(commentService.write(commentDto)==1);
        assertTrue(boardDao.select(bno).getComment_cnt() == 1);

        Integer cno = commentDao.selectAll(bno).get(0).getCno();

        // 일부러 예외를 발생시키고 Tx가 취소되는지 확인해야.
        int rowCnt = commentService.remove(cno, bno, commentDto.getCommenter());
        assertTrue(rowCnt==1);
        assertTrue(boardDao.select(bno).getComment_cnt() == 0);
    }

    @Test
    public void write() throws  Exception {
        boardDao.deleteAll();

        BoardDto boardDto = new BoardDto("hello", "hello", "asdf");
        assertTrue(boardDao.insert(boardDto) == 1);
        Integer bno = boardDao.selectAll().get(0).getBno();
        System.out.println("bno = " + bno);

        commentDao.deleteAll(bno);
        CommentDto commentDto = new CommentDto(bno,0,"hi","qwer");

        assertTrue(boardDao.select(bno).getComment_cnt() == 0);
        assertTrue(commentService.write(commentDto)==1);

        Integer cno = commentDao.selectAll(bno).get(0).getCno();
        assertTrue(boardDao.select(bno).getComment_cnt() == 1);
    }
}

Service 를 테스트 했다.

 

 

 

 

5) 컨트롤러 작성 & 테스트

 

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="https://code.jquery.com/jquery-1.11.3.js"></script>
</head>
<body>
<h2>commentTest</h2>
comment : <input type="text" name="comment"><br>
<button id="sendBtn" type="button">등록</button>
<button id="modBtn" type="button">수정</button>

<div id="commentList"></div>
<script>
    let bno = 1217;

    let showList = function(bno) {
        $.ajax({
            type:'GET',       // 요청 메서드
            url: '/ch4/comments?bno='+bno,  // 요청 URI
            success : function(result){
               $('#commentList').html(toHtml(result)); // 서버로부터 응답이 도착하면 호출될 함수
            },
            error   : function(){ alert("error") } // 에러가 발생했을 때, 호출될 함수
        }); // $.ajax()
    }

    $(document).ready(function(){
        showList(bno);

        $("#modBtn").click(function(){
            let cno = $(this).attr("data-cno");
            let comment = $("input[name=comment]").val();

            if(comment.trim()=='') {
                alert("댓글을 입력해주세요.")
                $("input[name=comment]").focus()
                return;
            }

            $.ajax({
                type:'PATCH',       // 요청 메서드
                url: '/ch4/comments/'+cno,  // 요청 URI // /ch4/comments/70 POST
                headers : { "content-type": "application/json"}, // 요청 헤더
                data : JSON.stringify({cno:cno, comment:comment}),  // 서버로 전송할 데이터. stringify()로 직렬화 필요.
                success : function(result){
                    alert(result);
                    showList(bno);
                },
                error   : function(){ alert("error") } // 에러가 발생했을 때, 호출될 함수
            }); // $.ajax()

        });

        $("#sendBtn").click(function(){
            let comment = $("input[name=comment]").val();

            if(comment.trim()=='') {
                alert("댓글을 입력해주세요.")
                $("input[name=comment]").focus()
                return;
            }

            $.ajax({
                type:'POST',       // 요청 메서드
                url: '/ch4/comments?bno='+bno,  // 요청 URI // /ch4/comments?bno=1217 POST
                headers : { "content-type": "application/json"}, // 요청 헤더
                data : JSON.stringify({bno:bno, comment:comment}),  // 서버로 전송할 데이터. stringify()로 직렬화 필요.
                success : function(result){
                    alert(result);
                    showList(bno);
                },
                error   : function(){ alert("error") } // 에러가 발생했을 때, 호출될 함수
            }); // $.ajax()

        });

        $("#commentList").on("click", ".modBtn", function() {
            let cno = $(this).parent().attr("data-cno");
            let comment = $("span.comment", $(this).parent()).text();
            // 1. comment의 내용을 input에 뿌려주기
            $("input[name=comment]").val(comment);
            // 2. cno전달하기
            $("#modBtn").attr("data-cno", cno);

        });

        // $(".delBtn").click(function() {
        $("#commentList").on("click", ".delBtn", function(){
            let cno = $(this).parent().attr("data-cno");
            let bno = $(this).parent().attr("data-bno");

            $.ajax({
                type:'DELETE',       // 요청 메서드
                url: '/ch4/comments/'+cno+'?bno='+bno,  // 요청 URI
                success : function(result){
                    alert(result)
                    showList(bno);
                },
                error   : function(){ alert("error") } // 에러가 발생했을 때, 호출될 함수
            }); // $.ajax()
        });

    });

    let toHtml = function (comments) {
        let tmp = "<ul>";

        comments.forEach(function(comment) {
            tmp += '<li data-cno='+ comment.cno
            tmp += ' data-pcno=' + comment.pcno
            tmp += ' data-bno=' + comment.bno + '>'
            tmp += ' commenter=<span class="commenter">' + comment.commenter + '</span>'
            tmp += ' comment=<span class="comment">' + comment.comment + '</span>'
            tmp += ' up_date='+comment.up_date
            tmp += '<button class="modBtn">수정</button>'
            tmp += '<button class="delBtn">삭제</button>'
            tmp += '</li>'
        })

        return tmp + "</ul>";
    }

</script>
</body>
</html>

view로 사용할 test.jsp를 만들었다.

 

 

package com.fastcampus.ch4.controller;

import com.fastcampus.ch4.dao.CommentDao;
import com.fastcampus.ch4.domain.CommentDto;
import com.fastcampus.ch4.service.CommentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpSession;
import java.util.List;

//@Controller
//@ResponseBody
@RestController
public class CommentController {
    @Autowired
    CommentService service;


//    {
//        "pcno" : 0,
//            "comment" : "hello",
//            "commenter" : "asdf"
//    }

    // 댓글을 수정하는 메소드
//    @ResponseBody
    @PatchMapping("/comments/{cno}") // /ch4/comments/42 PATCH
    public ResponseEntity<String> modify(@PathVariable Integer cno, @RequestBody CommentDto dto, HttpSession session) {
        // String commenter = (String)session.getAttribute("id");
        String commenter = "asdf";
        dto.setCommenter(commenter);
        dto.setCno(cno);
        System.out.println("dto = " + dto);

        try {
            if(service.modify(dto)!=1)
                throw new Exception("Modify failed.");

            return new ResponseEntity<>("MOD_OK", HttpStatus.OK);
        } catch (Exception e) {
            e.printStackTrace();
            return new ResponseEntity<>("MOD_ERR", HttpStatus.BAD_REQUEST);
        }
    }

    //    {
//        "pcno" : 0,
//            "comment" : "hi"
//    }

    // 댓글을 등록하는 메소드
//    @ResponseBody
    @PostMapping("/comments") // /ch4/comments?bno=1217 POST
    public ResponseEntity<String> write(@RequestBody CommentDto dto, Integer bno, HttpSession session) {
        // String commenter = (String)session.getAttribute("id");
        String commenter = "asdf";
        dto.setCommenter(commenter);
        dto.setBno(bno);
        System.out.println("dto = " + dto);

        try {
            if(service.write(dto)!=1)
                throw new Exception("Write failed.");

            return new ResponseEntity<>("WRT_OK", HttpStatus.OK);
        } catch (Exception e) {
            e.printStackTrace();
            return new ResponseEntity<>("WRT_ERR", HttpStatus.BAD_REQUEST);
        }
    }
        // 지정한 댓글을 삭제하는 메소드
    @DeleteMapping("/comments/{cno}") // comments/1?bno=1195 <-- 삭제할 댓글 번호
//    @ResponseBody
    public ResponseEntity<String> remove(@PathVariable Integer cno, Integer bno, HttpSession session) {
//        String commenter = (String)session.getAttribute("id");
        String commenter = "asdf";

        try {
            int rowCnt = service.remove(cno, bno, commenter);

            if(rowCnt!=1)
                throw new Exception("Delete failed");

            return new ResponseEntity<>("DEL_OK", HttpStatus.OK);
        } catch (Exception e) {
            e.printStackTrace();
            return new ResponseEntity<>("DEL_ERR", HttpStatus.BAD_REQUEST);
        }
    }
    
    // 지정한 게시물의 모든 댓글을 가져오는 메소드
    @GetMapping("/comments") // /comments?bno=1000 GET
//    @ResponseBody
    public ResponseEntity<List<CommentDto>> list(Integer bno) {
        List<CommentDto> list = null;
        try {
            list = service.getList(bno);
//            System.out.println("list = " + list);
            return new ResponseEntity<List<CommentDto>>(list, HttpStatus.OK); // 200
        } catch (Exception e) {
            e.printStackTrace();
            return new ResponseEntity<List<CommentDto>>(HttpStatus.BAD_REQUEST); // 400
        }

    }
}

컨트롤러를 만들었다.

 

 

 

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