ResponseEntity를 Customize(ApiResponse)

• 이렇게 ApiResult로 정의해서 반환하는 방식은 openAPI처럼 되게 형식적인 api일 때 이렇게 사용 보통함

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.springframework.http.HttpStatus;

public class ApiResult<T> {

  private final boolean success;

  private final T response;

  private final ApiError error;

  private ApiResult(boolean success, T response, ApiError error) {
    this.success = success;
    this.response = response;
    this.error = error;
  }

  public static <T> ApiResult<T> OK(T response) {
    return new ApiResult<>(true, response, null);
  }

  public static ApiResult<?> ERROR(Throwable throwable, HttpStatus status) {
    return new ApiResult<>(false, null, new ApiError(throwable, status));
  }

  public static ApiResult<?> ERROR(String errorMessage, HttpStatus status) {
    return new ApiResult<>(false, null, new ApiError(errorMessage, status));
  }

  public boolean isSuccess() {
    return success;
  }

  public ApiError getError() {
    return error;
  }

  public T getResponse() {
    return response;
  }

  @Override
  public String toString() {
    return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
      .append("success", success)
      .append("response", response)
      .append("error", error)
      .toString();
  }

}

import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.springframework.http.HttpStatus;

public class ApiError {

  private final String message;

  private final int status;

  ApiError(Throwable throwable, HttpStatus status) {
    this(throwable.getMessage(), status);
  }

  ApiError(String message, HttpStatus status) {
    this.message = message;
    this.status = status.value();
  }

  public String getMessage() {
    return message;
  }

  public int getStatus() {
    return status;
  }

  @Override
  public String toString() {
    return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
      .append("message", message)
      .append("status", status)
      .toString();
  }

}

@GetMapping(path = "user/{userId}/post/list")
  public ApiResult<List<PostDto>> posts(@PathVariable Long userId) {
    return OK(
      postService.findAll(Id.of(User.class, userId)).stream()
        .map(PostDto::new)
        .collect(toList())
    );
  }

• 모든 컨트롤러에서 반환값으로 ApiResult에 제네릭으로 써서 공통 부분을 풀어내기도 한다