1 Accept 指示能够接受的返回数据的范围 request-header
语法：
Accept = "Accept" ":" #( media-range[accept-params] )
media-range = ( "*/*"
| ( type "/" "*" )
| ( type "/" subtype )
) * ( ";" parameter )
accept-params = ";" "q" "=" qvalue *( accept-extension )
accept-extension = ";" token [ "=" ( token | quoted-string ) ]
例如：Accept: */*
2 Accept-Charset 指示返回数据的字符集 request-header
Accept-Charset = "Accept-Charset" ":"
1#( ( charset | "*" )[ ";" "q" "=" qvalue ] )
Accept-Charset: iso-8859-5, unicode-1-1;q=0.8
3 Accept-Encoding 有点类是Accept request-header
Accept-Encoding = "Accept-Encoding" ":"
1#( codings [ ";" "q" "=" qvalue ] )
codings = ( content-coding | "*" )
Accept-Encoding: *
4 Accept-Languagerequest-header
Accept-Language = "Accept-Language" ":"
1#( language-range [ ";" "q" "=" qvalue ] )
language-range = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )
5 Accept-Ranges 指明服务器能接受的请求资源范围 response-header
Accept-Ranges = "Accept-Ranges" ":" acceptable-ranges
acceptable-ranges = 1#range-unit | "none"
Accept-Ranges: bytes
6 Age 在第一次请求服务到下次服务器之间时间内，如果内容没有改变并且Age没有过期，
将传回缓存回发数据。response-header
Age = "Age" ":" age-value
age-value = delta-seconds
7 Allow 指示资源能被请求的形式entity-header
Allow = "Allow" ":" #Method
Allow: GET, HEAD, PUT
8 Authorization 用户授权
Authorization = "Authorization" ":" credentials
9 Cache-Control 指定必须遵循缓存机制 general-header
Cache-Control = "Cache-Control" ":" 1#cache-directive
cache-directive = cache-request-directive
| cache-response-directive
cache-request-directive =
"no-cache"
| "no-store"
| "max-age" "=" delta-seconds
| "max-stale" [ "=" delta-seconds ]
| "min-fresh" "=" delta-seconds
| "no-transform"
| "only-if-cached"
| cache-extension
cache-response-directive =
"public"
| "private" [ "=" <"> 1#field-name <"> ]
| "no-cache" [ "=" <"> 1#field-name <"> ]
| "no-store"
| "no-transform"
| "must-revalidate"
| "proxy-revalidate"
| "max-age" "=" delta-seconds
| "s-maxage" "=" delta-seconds
| cache-extension
cache-extension = token [ "=" ( token | quoted-string ) ]
10 Connectiongeneral-header
11 Content-Encodingentity-header
12 Content-Languageentity-header
13 Content-Lengthentity-header
14 Content-Locationentity-header
15 Content-MD5entity-header
16 Content-Rangeentity-header
17 Content-Typeentity-header
18 Dategeneral-header
19 ETagresponse-header
20 Expectrequest-header
21 Expiresentity-header
22 Fromrequest-header
23 Hostrequest-header
24 If-Match request-header
25 If-Modified-Sincerequest-header
26 If-None-Match request-header
27 If-Rangerequest-header
28 If-Unmodified-Sincerequest-header
29 Last-Modifiedentity-header
30 Locationresponse-header
31 Max-Forwards request-header
32 Pragma general-header
33 Proxy-Authenticate response-header
34 Proxy-Authorization request-header
35 Range
36 Refererrequest-header
37 Retry-After response-header
38 Serverresponse-header
39 TE request-header
40 Trailer general field
41 Transfer-Encoding general-header
42 Upgrade general-header
43 User-Agentrequest-header
User-Agent = "User-Agent" ":" 1*( product | comment )
44 Vary
45 Via general-header
46 Warning general-header
47 WWW-Authenticate response-header