响应头字段可以提供补充状态码，缓存指令，或指示客户端接下来去哪的控制数据。

    1.    +-------------------+--------------------------+
    2.    | Header Field Name | Defined in...            |
    3.    +-------------------+--------------------------+
    4.    | Age               | Section 5.1 of [RFC7234] |
    5.    | Cache-Control     | Section 5.2 of [RFC7234] |
    6.    | Expires           | Section 5.3 of [RFC7234] |
    7.    | Date              | Section 7.1.1.2          |
    8.    | Location          | Section 7.1.2            |
    9.    | Retry-After       | Section 7.1.3            |
    10.    | Vary              | Section 7.1.4            |
    11.    | Warning           | Section 5.5 of [RFC7234] |
    12.    +-------------------+--------------------------+