Post 方法不读取 json，只有 Spring Boot api 中的 String

Question

我正在开发一个简单的 CRUD api，但我的 post 方法不起作用，每次发送 json 格式的数据时都会引发此异常

{
    "title": "Cannot construct instance of `academy.devdojo.springboot2.requests.AnimePostRequestBody` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator)\n at [Source: (PushbackInputStream); line: 2, column: 5]",
    "status": 400,
    "details": "JSON parse error: Cannot construct instance of `academy.devdojo.springboot2.requests.AnimePostRequestBody` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `academy.devdojo.springboot2.requests.AnimePostRequestBody` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator)\n at [Source: (PushbackInputStream); line: 2, column: 5]",
    "developerMessage": "org.springframework.http.converter.HttpMessageNotReadableException",
    "timestamp": "2022-01-13T14:45:34.9138659"
}

它只在发送一个简单的字符串比如“要保存的名字”时才有效，而不是

{
  "name" : "some name to be saved"
}

这是我的课

实体

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Builder
public class Anime {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotEmpty(message= "anime name cannot be empty")
    private String name;

}

回购

public interface AnimeRepository extends JpaRepository<Anime, Long> {
    List<Anime> findByName(String name);
}

服务

@Service
@RequiredArgsConstructor
public class AnimeService {

    private final AnimeRepository animeRepository;

    public Page<Anime> listAll(Pageable pageable) {

        return animeRepository.findAll(pageable);
    }

    public List<Anime> findByName(String name) {
        List<Anime> byName = animeRepository.findByName(name);
        if (byName.isEmpty()){
            throw new BadRequestException("Anime not Found");
        }
        return byName;
    }

    public Anime findByIdOrThrowBadRequestException(long id) {
        return animeRepository.findById(id)
                .orElseThrow(() -> new BadRequestException("Anime not Found"));
    }


    public Anime save(AnimePostRequestBody animePostRequestBody) {

        Anime anime = AnimeMapper.INSTANCE.toAnime(animePostRequestBody);

        return animeRepository.save(anime);
    }

    public void delete(long id) {

        animeRepository.delete(findByIdOrThrowBadRequestException(id));
    }

    public void replace(AnimePutRequestBody animePutRequestBody) {

        Anime savedAnime  = findByIdOrThrowBadRequestException(animePutRequestBody.getId());

        Anime anime = AnimeMapper.INSTANCE.toAnime(animePutRequestBody);

        anime.setId(savedAnime.getId());

        animeRepository.save(anime);
    }

    public List<Anime> listAllNonPageable() {
        return animeRepository.findAll();
    }
}

休息控制器

@RestController
@Api(tags = "Atividades Economicas")
@RequestMapping("animes")
@Log4j2
@RequiredArgsConstructor
public class AnimeController {
    private final DateUtil dateUtil;
    private final AnimeService animeService;

    @ApiOperation(value = "Listar todos")
    @GetMapping
    public ResponseEntity<Page<Anime>> list(Pageable pageable) {
        //log.info(dateUtil.formatLocalDateTimeToDatabaseStyle(LocalDateTime.now()));
        return ResponseEntity.ok(animeService.listAll(pageable));
    }

    @GetMapping(path = "/all")
    public ResponseEntity<List<Anime>> listAll() {
        //log.info(dateUtil.formatLocalDateTimeToDatabaseStyle(LocalDateTime.now()));
        return ResponseEntity.ok(animeService.listAllNonPageable());
    }
    @ApiOperation(value = "Listar por ID")
    @GetMapping(path = "/{id}")
    public ResponseEntity<Anime> findById(@PathVariable long id) {
        return ResponseEntity.ok(animeService.findByIdOrThrowBadRequestException(id));
    }

    @ApiOperation(value = "Encontrar pelo nome")
    @GetMapping(path = "/find")
    public ResponseEntity<List<Anime>> findByName(@RequestParam String name) {
        return ResponseEntity.ok(animeService.findByName(name));
    }


    @PostMapping
    public ResponseEntity<Anime> save(@RequestBody @Valid AnimePostRequestBody animePostRequestBody) {
        return new ResponseEntity<>(animeService.save(animePostRequestBody), HttpStatus.CREATED);
    }


    @DeleteMapping(path = "/{id}")
    public ResponseEntity<Void> delete(@PathVariable long id) {
        animeService.delete(id);
        return new ResponseEntity<>(HttpStatus.NO_CONTENT);
    }

    @PutMapping
    public ResponseEntity<Void> replace(@RequestBody AnimePutRequestBody animePutRequestBody) {
        animeService.replace(animePutRequestBody);
        return new ResponseEntity<>(HttpStatus.NO_CONTENT);
    }
}

DTO 的

@Data
@Builder
public class AnimePostRequestBody {

   @NotEmpty(message= "anime name cannot be empty")
    private String name;

}

@Data
@Builder
public class AnimePutRequestBody {
    private Long id;
    private String name;
}

映射器

@Mapper(componentModel = "spring")
public abstract class AnimeMapper {

    public static  final AnimeMapper INSTANCE = Mappers.getMapper(AnimeMapper.class);

    public abstract Anime toAnime(AnimePostRequestBody animePostRequestBody);
    public abstract Anime toAnime(AnimePutRequestBody animePutRequestBody);
}

附言尽管它们非常相似，但 put 方法运行良好。

Answer 1

@Data 是一个方便的快捷注解，将@ToString、@EqualsAndHashCode、@Getter/@Setter 和@RequiredArgsConstructor 的功能捆绑在一起

需要默认构造函数。添加 lombok 的 @NoArgsConstructor 注解。

Answer 2

除了 Model 类，DTO 类还应该包含 @AllArgsConstructor 和 @NoArgsConstructor。要将 RequestBody 值映射到 DTO，它需要构造函数，而 @Data 不提供 @AllArgsConstructor 和 @NoArgsConstructor 构造函数。

Answer 3

//实体

    @Data
    @Entity
    @Table(name = "Anime")
    @Builder
    public class Anime {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotEmpty(message= "anime name cannot be empty")
    private String name;

}

//回购

@Repository
public interface AnimeRepository extends JpaRepository<Anime, Long> {
}

//DTO

@Getter
public class AnimePostRequestBody {

    @NotEmpty(message = "anime name cannot by empty")
    private String name;
}

//控制器

@RestController
@RequestMapping("animes")
public class AnimeController {

    @Autowired
    private AnimeService animeService;

    @PostMapping
    public ResponseEntity<Anime> save(@RequestBody @Valid AnimePostRequestBody animePostRequestBody) {
        return new ResponseEntity<>(animeService.save(animePostRequestBody), HttpStatus.CREATED);
    }


}

//服务

@Service
public class AnimeService {

    @Autowired
    private AnimeRepository animeRepository;

    public Anime save(AnimePostRequestBody animePostRequestBody) {
        Anime anime = Anime.builder()
                .name(animePostRequestBody.getName())
                .build();
        return animeRepository.save(anime);
    }
}

输出

{ “身份证”：4， “名称”：“火影忍者” }

Answer 4

替换这一行

 public ResponseEntity<Anime> save(@RequestBody @Valid AnimePostRequestBody animePostRequestBody){..

用这个：

 public ResponseEntity<Anime> save(@Valid @RequestBody AnimePostRequestBody animePostRequestBody)