[Spring Boot] REST API 만들기(13) - 예외 처리 및 테스트

스프링 MVC에서는 애플리케이션에서 발생하는 예외를 처리할 때는 @ExceptionHandler 어노테이션과 @ControllerAdvice 어노테이션을 사용합니다. @ExceptionHandler은 전체 애플리케이션의 예외 처리를 하지 못하기 때문에, 전체 애플리케이션의 예외 처리가 가능하고, ReponseEntity 형식을 사용할 수 있는 @ControllerAdvice 어노테이션을 이용해서 예외 처리를 하도록 하겠습니다.

 

1. ResourceNotFoundException.java 추가

자원을 찾을 수 없다는 예외를 처리하기 위해 com.spring.board.exception 패키지를 생성한 후 ResourceNotFoundException 클래스를 추가하세요.

ResourceNotFoundException.java

package com.api.board.exception;
 
public class ResourceNotFoundException extends RuntimeException {
 
}

 

2. BoardController.java 수정

게시글 상세 조회 시 값이 null인 경우 ResourceNotFoundException을 발생하도록 수정하세요.

BoardController.java

package com.api.board.controller;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
 
import com.api.board.domain.Board;
import com.api.board.domain.Boards;
import com.api.board.exception.ResourceNotFoundException;
import com.api.board.service.BoardService;
 
@RequestMapping("/board")
@RestController
public class BoardController {
 
    @Autowired
    private BoardService boardService;
 
    /** 게시글 목록 조회 */
    @GetMapping
    public Boards getBoardList() throws Exception {
        
        Boards boards = new Boards();
        boards.setBoards(boardService.getBoardList());
        
        return boards;
    }
 
    /** 게시글 상세 조회 */
    @GetMapping("/{board_seq}")
    public Board getBoardDetail(@PathVariable("board_seq") int board_seq) throws Exception {
        
        Board board = boardService.getBoardDetail(board_seq);
        
        if(board == null) {
            throw new ResourceNotFoundException();
        }
        
        return board; 
    }
 
    /** 게시글 등록  */
    @ResponseStatus(value = HttpStatus.CREATED)
    @PostMapping
    public Board insertBoard(@RequestBody Board board) throws Exception {
 
        boardService.insertBoard(board);
 
        int boardSeq = board.getBoard_seq();
 
        Board boardDetail = boardService.getBoardDetail(boardSeq);
 
        return boardDetail;
    }
 
    /** 게시글 수정 */
    @ResponseStatus(value = HttpStatus.OK)
    @PutMapping("/{board_seq}")
    public Board updateBoard(@PathVariable("board_seq") int board_seq, @RequestBody Board board) throws Exception {
 
        boardService.updateBoard(board);
 
        Board boardDetail = boardService.getBoardDetail(board_seq);
 
        return boardDetail;
    }
 
    /** 게시글 삭제  */
    @ResponseStatus(value = HttpStatus.OK)
    @DeleteMapping("/{board_seq}")
    public Board deleteBoard(@PathVariable("board_seq") int board_seq) throws Exception {
 
        boardService.deleteBoard(board_seq);
 
        Board deleteBoard = new Board();
        deleteBoard.setBoard_seq(board_seq);
 
        return deleteBoard;
    }
}

 

3. ResponseError.java 추가

REST 서비스에서는 HTTP 상태 코드를 가지고 결과 값을 판단하기 때문에 앞에서 구현한 것 처럼 간단하게 에러 결과를 처리할 수 있습니다. 하지만 요청이 JSON 형식이면 에러 결과도 JSON 형식으로 보여주는 것이 좋기 때문에 에러 결과를 처리하기 위해 com.spring.board.exception.domain 패키지를 생성한 후 ResponseError 클래스를 생성하세요. XML 형식으로도 사용하기 위해서 @XmlRootElement 어노테이션 클래스도 추가하세요.

ResponseError.java

package com.api.board.exception.domain;
 
import javax.xml.bind.annotation.XmlRootElement;
 
@XmlRootElement(name = "error")
public class ResponseError {
 
    private int code;
    private String message;
 
    public ResponseError() {
    }
 
    public ResponseError(int code, String message) {
        this.code = code;
        this.message = message;
    }
 
    public int getCode() {
        return code;
    }
 
    public void setCode(int code) {
        this.code = code;
    }
 
    public String getMessage() {
        return message;
    }
 
    public void setMessage(String message) {
        this.message = message;
    }
}

 

4. ResponseEntityExceptionHandler.java 추가

com.spring.board.exception.handle 패키지를 생성한 후 ResponseEntityExceptionHandler 클래스를 추가하세요.

@ControllerAdvice 어노테이션을 클래스에 선언하고, @ExceptionHandler 어노테이션을 사용해서 처리할 예외를 정한 다음에 @ResponseBody 어노테이션을 이용해서 응답 결과를 반환하세요.

ResponseEntityExceptionHandler.java

package com.api.board.domain.handle;
 
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;
 
import com.api.board.exception.ResourceNotFoundException;
import com.api.board.exception.domain.ResponseError;
 
@ControllerAdvice
public class ResponseEntityExceptionHandler {
 
    @ExceptionHandler(value = { ResourceNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public ResponseError handleResourceNotFound(ResourceNotFoundException e) {
        ResponseError responseError = new ResponseError(404, "Resource가 존재하지 않습니다.");
        return responseError;
    }
}

 

5. WebMvcConfig.java 수정

예외를 처리하는 ResponseEntityExceptionHandler 클래스는 @ControllerAdvice 어노테이션을 사용하기 때문에 WebMvcConfig 설정에서  ResponseEntityExceptionHandler 클래스를 자동으로 스캔하도록 @ComponentScan의 includeFilters 부분에 ControllerAdvice를 추가하세요.

WebMvcConfig.java

package com.api.board.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.http.converter.xml.MarshallingHttpMessageConverter;
import org.springframework.oxm.jaxb.Jaxb2Marshaller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
import com.api.board.interceptor.BoardInterceptor;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.module.jaxb.JaxbAnnotationModule;
 
@ComponentScan(basePackages = {"com.api.board.controller"}, useDefaultFilters = false, includeFilters = {@Filter(Controller.class), @Filter(ControllerAdvice.class)})
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
 
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new BoardInterceptor())
                .addPathPatterns("/**")
                .excludePathPatterns("/sample/**");
    }
    
    @Bean
    public MappingJackson2HttpMessageConverter mappingJacksonHttpMessageConverter() {
 
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        
        ObjectMapper objectMapper = converter.getObjectMapper();
        objectMapper.configure(DeserializationFeature.UNWRAP_ROOT_VALUE, true);
        objectMapper.configure(SerializationFeature.WRAP_ROOT_VALUE, true);
 
        JaxbAnnotationModule module = new JaxbAnnotationModule();
        objectMapper.registerModule(module);
 
        return converter;
    }
    
    @Bean
    public MarshallingHttpMessageConverter marshallingHttpMessageConverter() {
        MarshallingHttpMessageConverter converter = new MarshallingHttpMessageConverter();
        converter.setMarshaller(jaxb2Marshaller());
        converter.setUnmarshaller(jaxb2Marshaller());
        return converter;
    }
    
    @Bean
    public Jaxb2Marshaller jaxb2Marshaller() {
        Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
        marshaller.setPackagesToScan(new String[] { "com.api.board.domain" });
        return marshaller;
    }
    
    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer.favorParameter(true)
                  .ignoreAcceptHeader(false)
                  .defaultContentType(MediaType.APPLICATION_JSON)
                  .mediaType("json", MediaType.APPLICATION_JSON)
                  .mediaType("xml", MediaType.APPLICATION_XML);
    }
}

 

6. 예외 테스트

ResponseEntityExceptionHandler가 정상적으로 작동하는지 테스트하기 위해 존재하지 않는 게시글 상세 조회 API를 호출 시, ResourceNotFoundException이 발생하고 ResponseEntityExceptionHandler 클래스의 handleResourceNotFound 메소드가 실행되어 404 코드가 응답되는지 확인하세요.

BoardControllerExceptionTest.java

package com.api.board.controller;
 
import static org.junit.Assert.assertEquals;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
 
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.filter.CharacterEncodingFilter;
 
@WebAppConfiguration
@RunWith(SpringRunner.class)
@SpringBootTest
public class BoardControllerExceptionTest {
 
    Logger logger = LoggerFactory.getLogger(BoardControllerExceptionTest.class);
 
    private MockMvc mockMvc;
 
    @Autowired
    WebApplicationContext webApplicationContext;
  
    @Before
    public void setUp() {
        mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext)
                                 .addFilters(new CharacterEncodingFilter("UTF-8", true))
                                 .alwaysDo(print())
                                 .build();
    }
 
    int boardSeq = 0;
    
    /** 게시글 상세 조회 시 응답 값이 404이면 테스트 통과 */
    @Test
    public void getBoardDetailJSON(){
 
        try {
            
            if (boardSeq != 0) {
                
                MvcResult mvcResult = mockMvc.perform(MockMvcRequestBuilders.get("/board/" + boardSeq)
                         .accept(MediaType.APPLICATION_XML))
                         .andReturn();
 
                assertEquals(404, mvcResult.getResponse().getStatus());    
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    /** 게시글 상세 조회 시 응답 값이 404이면 테스트 통과 */
    @Test
    public void getBoardDetailXML() throws Exception {
        
        try {
            
            if (boardSeq != 0) {
                
                MvcResult mvcResult = mockMvc.perform(MockMvcRequestBuilders.get("/board/" + boardSeq)
                         .accept(MediaType.APPLICATION_JSON))
                         .andReturn();
 
                assertEquals(404, mvcResult.getResponse().getStatus());    
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

 

소스 코드는 Github Repository - https://github.com/tychejin1218/api-board_v1 (branch : section13) 를 참조하세요.
Github에서 프로젝트 가져오기 - https://tychejin.tistory.com/33