Content-Encoding
- это сущность заголовка, используемая для сжатия медиа-типа. При наличии ее значение определяет кодировку, примененную к сущности body
. Это позволяет клиенту информацию как декодировать body
, чтобы получить медиа-тип ссылающийся на заголовок Content-Type
Рекомендация - сжимать данные насколько это возможно и следовательно использовать это поле, но некоторые типы данных, такие как изображения в формате jpeg, уже сжаты. Иногда, использование дополнительного сжатия не уменьшает размер пакета и даже может сделать загрузку дольше.
Header type | Entity header |
---|---|
Forbidden header name | no |
Синтаксис
Content-Encoding: gzip Content-Encoding: compress Content-Encoding: deflate Content-Encoding: identity Content-Encoding: br // Multiple, in the order in which they were applied Content-Encoding: gzip, identity Content-Encoding: deflate, gzip
Директивы
gzip
- A format using the Lempel-Ziv coding (LZ77), with a 32-bit CRC. This is the original format of the UNIX gzip program. The HTTP/1.1 standard also recommends that the servers supporting this content-encoding should recognize
x-gzip
as an alias, for compatibility purposes. compress
- A format using the Lempel-Ziv-Welch (LZW) algorithm. The value name was taken from the UNIX compress program, which implemented this algorithm. Like the compress program, which has disappeared from most UNIX distributions, this content-encoding is not used by many browsers today, partly because of a patent issue (it expired in 2003).
deflate
- Using the zlib structure (defined in RFC 1950) with the deflate compression algorithm (defined in RFC 1951).
identity
- Indicates the identity function (i.e., no compression or modification). This token, except if explicitly specified, is always deemed acceptable.
br
- A format using the Brotli algorithm.
Examples
Compressing with gzip
On the client side, you can advertise a list of compression schemes that will be sent along in an HTTP request. The Accept-Encoding
header is used for negotiating content encoding.
Accept-Encoding: gzip, deflate
The server responds with the scheme used, indicated by the Content-Encoding
response header.
Content-Encoding: gzip
Note that the server is not obligated to use any compression method. Compression highly depends on server settings and used server modules.
Specifications
Specification | Title |
---|---|
RFC 7932: Brotli Compressed Data Format | Brotli Compressed Data Format |
RFC 7231, секция 3.1.2.2: Content-Encoding | Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content |
RFC 2616, секция 14.11: Content-Encoding | Content-Encoding |
Browser compatibility
BCD tables only load in the browser
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.