swagger -- ref 自定义的使用

400err定义了一个可重用的响应，它指定了我们在所有端点下使用的400响应，然后进行适当的引用。

swagger: '2.0'info:  version: 1.0.0  title: Simple Artist API  description: A simple API to understand the Swagger specification in greater detailschemes: - httpshost: example.iobasePath: /v1securityDefinitions:  UserSecurity:    type: basicsecurity:  - UserSecurity: [] paths:  /artists:    get:      description: Returns a list of artists       parameters:        - $ref: '#/parameters/PageLimit'        - $ref: '#/parameters/PageNumber'              responses:        200:          description: Successfully returned a list of artists           schema:            type: array            items:              $ref: '#/definitions/Artist'                          400:          #  ----- Added line  ----------------------------------------          $ref: '#/responses/400Error'          #  ---- /Added line  ----------------------------------------                post:      description: Lets a user post a new artist      parameters:        - name: artist          in: body          description: creates a new artist in our database          schema:            $ref: '#/definitions/Artist'                      responses:        200:          description: Successfully created a new artist                  400:          #  ----- Added line  ----------------------------------------          $ref: '#/responses/400Error'          #  ---- /Added line  ----------------------------------------      /artists/{username}:    get:      description: Obtain information about an artist from his or her unique username      parameters:        - name: username          in: path           type: string          required: true                 responses:        200:          description: Successfully returned an artist          schema:            type: object            properties:              artist_name:                type: string              artist_genre:                type: string              albums_recorded:                type: integer                        400:          #  ----- Added line  ----------------------------------------          $ref: '#/responses/400Error'          #  ---- /Added line  ----------------------------------------                                definitions:  Artist:    type: object    required:      - username    properties:      artist_name:        type: string      artist_genre:          type: string      albums_recorded:          type: integer      username:          type: string#  ----- Added lines  ----------------------------------------parameters:  PageLimit:    name: limit    in: query    type: integer    description: Limits the number of items on a page      PageNumber:    name: offset    in: query    type: integer    description: Specifies the page number of the artists to be displayedresponses:  400Error:    description: Invalid request    schema:      type: object       properties:        message:          type: string#  ---- /Added lines  ----------------------------------------