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Content-Encoding
Baseline Widely available *
This feature is well established and works across many devices and browser versions. It’s been available across browsers since июль 2015 г..
* Some parts of this feature may have varying levels of support.
Content-Encoding - это сущность заголовка, используемая для сжатия медиа-типа. При наличии её значение определяет кодировку, применённую к сущностиbody. Это позволяет клиенту информацию как декодироватьbody, чтобы получить медиа-тип ссылающийся на заголовокContent-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: gzipContent-Encoding: compressContent-Encoding: deflateContent-Encoding: identityContent-Encoding: br// Multiple, in the order in which they were appliedContent-Encoding: gzip, identityContent-Encoding: deflate, gzip
Директивы
gzipA format using theLempel-Ziv coding (LZ77), with a 32-bit CRC. This is the original format of the UNIXgzip program. The HTTP/1.1 standard also recommends that the servers supporting this content-encoding should recognize
x-gzipas an alias, for compatibility purposes.compressA format using theLempel-Ziv-Welch (LZW) algorithm. The value name was taken from the UNIXcompress 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).
deflateUsing thezlib structure (defined inRFC 1950) with thedeflate compression algorithm (defined inRFC 1951).
identityIndicates the identity function (i.e., no compression or modification). This token, except if explicitly specified, is always deemed acceptable.
brA format using theBrotli 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. TheAccept-Encoding header is used for negotiating content encoding.
Accept-Encoding: gzip, deflateThe server responds with the scheme used, indicated by theContent-Encoding response header.
Content-Encoding: gzipNote that the server is not obligated to use any compression method. Compression highly depends on server settings and used server modules.
Спецификации
| Specification |
|---|
| HTTP Semantics # field.content-encoding |
| Zstandard Compression and the 'application/zstd' Media Type # name-content-encoding |