http_cache_etag

(PECL pecl_http >= 0.1.0)

http_cache_etag — Caching by ETag

说明

bool http_cache_etag ([ string $etag ] )

Attempts to cache the sent entity by its ETag, either supplied or generated by the hash algorithm specified by the INI 设置 http.etag.mode.

If the clients If-None-Match header matches the supplied/calculated ETag, the body is considered cached on the clients side and a 304 Not Modified status code is issued.

A log entry is written to the cache log if the INI 设置 http.log.cache is set and the cache attempt was successful.

Note: 此函数可与 http_send_data() , http_send_file() 和 http_send_stream() 一同使用。

If this function is used outside the http_send_*() API, it facilitates the ob_etaghandler() .

参数

etag: custom ETag

返回值

返回 FALSE 或在成功时返回出口信息 with 304 Not Modified if the entity is cached. 要知道“出口”的含义请查阅 INI 设置 http.force_exit。

范例

Example #1 A http_cache_etag() example

  <?php
http_cache_etag ();
 http_send_data ( "data" );
 ?>

参见

http_cache_last_modified() - Caching by last modification
ob_etaghandler() - ETag output handler
http_match_etag() - Match ETag
如使用 PHP 5.1.0 及以后版本中为 HttpResponse 类。