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文字

If-RangeHTTP 请求报头使得范围请求的条件:如果条件被满足,该范围的请求将被发出,并且服务器发送回一个206 Partial Content与适当的身体的答案。如果条件未满足,则会返回具有200 OK状态的完整资源。

这个头文件可以与Last-Modified验证器一起使用,也可以与一个ETag,但不与两者一起使用。

最常见的用例是恢复下载,以确保自从收到最后一个片段后,存储的资源未被修改。

Header type

Request header

Forbidden header name

no

句法

If-Range: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT
If-Range: <etag>

指令

<etag>唯一表示请求资源的实体标记。它是位于双引号(像 "675af34563dc-tr34")之间的一串 ASCII 字符,可以加前缀W/以表示应使用弱比较算法。<day-name>“星期一”,“星期二”,“星期三”,“星期二“,”星期五“,”星期六“或”太阳“(区分大小写)。<day> 2位数日期编号,例如”04“或”23“。<month> ,“Mar”,“Apr”,“May”,“Jun”,“Jul”,“Aug”,“Sep”,“Oct”,“Nov”,“Dec”(区分大小写)例如“1990”或“2016”。<小时> 2位数的小时数,例如 “09”GMT

格林威治标准时间。HTTP 日期总是以 GMT 表示,从不以本地时间表示。

例子

If-Range: Wed, 21 Oct 2015 07:28:00 GMT

产品规格

Specification

Title

RFC 7233, section 3.2: If-Range

Hypertext Transfer Protocol (HTTP/1.1): Range Requests

浏览器兼容性

Feature

Chrome

Firefox

Edge

Internet Explorer

Opera

Safari

Basic Support

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

Feature

Android

Chrome for Android

Edge mobile

Firefox for Android

IE mobile

Opera Android

iOS Safari

Basic Support

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

请参阅

  • ETag

  • Last-Modified

  • If-Modified-Since

  • If-Unmodified-Since

  • If-Match

  • If-None-Match

  • 206 Partial Content

  • HTTP 条件请求

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