OpenAPI定義からREST APIソースコードの自動生成方法の紹介

{ 
    "interfaceOnly": "true", 
    "apiPackage": "hoge.piyo.generated.api", 
    "modelPackage": "hoge.piyo.generated.model"
}

openapi: 3.0.0
info:
  title: openapi
  version: '1.0'
servers:
  - url: 'http://localhost:8080'
paths:
  '/product':
    post:
      operationId: post-product
      tags:
        - Product
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ProductRequest'
      responses:
        '200':
          description: OK
  '/product/{product_id}':
    parameters:
      - schema:
          type: string
        name: product_id
        in: path
        required: true
    get:
      operationId: get-product-product_id
      tags:
        - Product
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProductResponse'
components:
  schemas:
    ProductResponse:
      title: ProductResponse
      type: object
      properties:
        id:
          type: string
        name:
          type: string
        price:
          type: integer
      required:
        - id
        - name
        - price
    ProductRequest:
      title: ProductRequest
      type: object
      properties:
        name:
          type: string
        price:
          type: integer
      required:
        - name
        - price

/**
 * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
 * https://openapi-generator.tech
 * Do not edit the class manually.
 */
package hoge.piyo.generated.api;

import hoge.piyo.generated.model.ProductRequest;
import hoge.piyo.generated.model.ProductResponse;
import ...

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen", date = "2022-09-08T11:56:15.267619500+09:00[Asia/Tokyo]")
@Validated
@Tag(name = "product", description = "the product API")
public interface ProductApi {

    default Optional<NativeWebRequest> getRequest() {
        return Optional.empty();
    }

    /**
     * GET /product/{product_id}
     *
     * @param productId  (required)
     * @return OK (status code 200)
     */
    @Operation(
        operationId = "getProductProductId",
        tags = { "Product" },
        responses = {
            @ApiResponse(responseCode = "200", description = "OK", content = @Content(mediaType = "application/json", schema = @Schema(implementation =  ProductResponse.class)))
        }
    )
    @RequestMapping(
        method = RequestMethod.GET,
        value = "/product/{product_id}",
        produces = { "application/json" }
    )
    default ResponseEntity<ProductResponse> getProductProductId(
        @Parameter(name = "product_id", description = "", required = true, schema = @Schema(description = "")) @PathVariable("product_id") String productId
    ) {
        getRequest().ifPresent(request -> {
            for (MediaType mediaType: MediaType.parseMediaTypes(request.getHeader("Accept"))) {
                if (mediaType.isCompatibleWith(MediaType.valueOf("application/json"))) {
                    String exampleString = "{ \"price\" : 0, \"name\" : \"name\", \"id\" : \"id\" }";
                    ApiUtil.setExampleResponse(request, "application/json", exampleString);
                    break;
                }
            }
        });
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);

    }


    /**
     * POST /product
     *
     * @param productRequest  (optional)
     * @return OK (status code 200)
     */
    @Operation(
        operationId = "postProduct",
        tags = { "Product" },
        responses = {
            @ApiResponse(responseCode = "200", description = "OK")
        }
    )
    @RequestMapping(
        method = RequestMethod.POST,
        value = "/product",
        consumes = { "application/json" }
    )
    default ResponseEntity<Void> postProduct(
        @Parameter(name = "ProductRequest", description = "", schema = @Schema(description = "")) @Valid @RequestBody(required = false) ProductRequest productRequest
    ) {
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);

    }

}

@RestController
public class ProductController implements ProductApi {
    ...
}