예외처리(Exception)기능 + Response 기능(데이터 반환) 을 추가한 게시판 만들기 코드

 

Response 

package com.example.mentoring.Response;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.sun.net.httpserver.Authenticator;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Getter;

@JsonInclude(JsonInclude.Include.NON_NULL)// Null 버림
@AllArgsConstructor(access = AccessLevel.PRIVATE)
@Getter

public class Response {
    private boolean success;
    private int code;
    private Result result;
//    데이터 없이 성공 반환
    public static Response success(){
        return new Response(true,0,null);
    }
//    데이터 포함해서 성공 반환
    public static <T> Response success(T data){
        return new Response(true,0,new Success<>(data));
    }
//    에러 발생시 반환해주는 경우
    public static Response failure(int code, String msg){
        return new Response(false, code, new Failure(msg));
    }

}

Result

package com.example.mentoring.Response;

interface Result {
}

Success

package com.example.mentoring.Response;

import com.fasterxml.jackson.annotation.JsonInclude;
import lombok.AllArgsConstructor;
import lombok.Getter;

@JsonInclude(JsonInclude.Include.NON_NULL)
//null값을 가지는 필드는 JSON응답에 포함되지 않음
@Getter
@AllArgsConstructor
public class Success<T> implements Result {
    private T data; // T는 어떤 타입이 와도 상관없음을 의미
}

Failure

package com.example.mentoring.Response;

import lombok.AllArgsConstructor;
import lombok.Getter;

@Getter
@AllArgsConstructor
public class Failure implements Result{
    private String msg;
}

Exception

WriterNotFoundException : 작성자 예외처리
public class WriterNotFoundException extends RuntimeException{
}
BoardNotFoundException : 게시글 예외처리
public class BoardNotFoundException extends RuntimeException{
}

ExceptionAdvice

package com.example.mentoring.advice;

import com.example.mentoring.Response.Response;
import com.example.mentoring.exception.BoardNotFoundException;
import com.example.mentoring.exception.WriterNotFoundException;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice // @RestController + @Advice
//ExceptionAdvice == Exception을 관리하기 위한 통제소 == 실패할 경우 실패 메세지를 보내기 위한 RestController
public class ExceptionAdvice {
    //404 NotFound Error

    @ExceptionHandler(BoardNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public Response boardNotFoundException(){
        return Response.failure(404,"게시글을 찾을 수 없습니다.");
    }

    // 404 NotFound
    @ExceptionHandler(WriterNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public Response writerNotFoundException(){
        return Response.failure(404, "작성자를 입력해주세요.");
    }
}

BoardController

package com.example.mentoring.controller;


import com.example.mentoring.Response.Response;
import com.example.mentoring.entity.Board;
import com.example.mentoring.service.BoardService;
import lombok.RequiredArgsConstructor;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;


@RestController //RestAPI 서버
@RequiredArgsConstructor //@Non null + static 생성자

public class BoardController {
    private final BoardService boardService;
    
    @ResponseStatus(HttpStatus.OK)
    @GetMapping("/boards")
    
    public Response getBoards(){
        return Response.success(boardService.getBoards());
    }
    
    @ResponseStatus(HttpStatus.OK)
    @GetMapping("/boards/{id}")
    public Response getBoard(@PathVariable("id") Long id){
        return Response.success(boardService.getBoard(id));
    }
    
    @ResponseStatus(HttpStatus.OK)
    @PostMapping("/boards")
    public Response editBoard(@PathVariable("id") Long id, @RequestBody Board updateBoard){
        return Response.success(boardService.editBoard(id,updateBoard));
    }
    
    @ResponseStatus(HttpStatus.OK)
    @PutMapping("/boards/{id}")
    public Response editBoard(@PathVariable("id") Long id, @RequestBody Board updateBoard){
        return Response.success(boardService.editBoard(id,updateBoard));
    }
    
    @ResponseStatus(HttpStatus.OK)
    @DeleteMapping("/api/boards/{id}")
    public Response deleteBoard(@PathVariable("id") Long id){
        boardService.deleteBoard(id);
        return Response.success("삭제 완료");
    }

BoardRepository

   Board board = boardRepository.findById(id).get();에서
   예외처리를 추가하였기에 이렇게 코드를 수정해준다.
   Board board = boardRepository.findById(id).orElseThrow(BoardNotFoundException::new);
   이 코드로 인해, 어떤 오류가 발생했는지 알 수 있게 된다.