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| Header | Explanation | Example |
|---|---|---|
| Accept | Specifies the type of content the client can receive | Accept: text/plain, text/html |
| Accept-Charset | The set of character encodings that the browser can accept. | Accept-Charset: iso-8859-5 |
| Accept-Encoding | Specifies the type of compression encoding that the browser can support for the content returned by the web server. | Accept-Encoding: compress, gzip |
| Accept-Language | Browser-acceptable languages | Accept-Language: en,zh |
| Accept-Ranges | One or more sub-scope fields of the web page entity that can be requested | Accept-Ranges: bytes |
| Authorization | Authorization certificate for HTTP authorization | Authorization: Authorization certificate |
| Cache-Control | Specifies the caching mechanism that requests and responses follow | Cache-Control: no-cache |
| Connection | Indicates whether a persistent connection is required. (HTTP 1.1 makes persistent connections by default) | Connection: close |
| Cookie | HTTP requests are sent to the web server with all cookie values saved under the domain name of the request. | Cookie: $Version=1; Skin=new; |
| Content-Length | The length of the requested content | Content-Length: 348 |
| Content-Type | The requested MIME information corresponding to the entity | Content-Type: application/x-www-form-urlencoded |
| Date | The date and time the request was sent | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| Expect | Server behavior specific to the request | Expect: 100-continue |
| From | Email of the user who sent the request | From: [email protected] |
| Host | Domain name and port number of the server that specified the request | Host: www.jsons.cn |
| If-Match | Only valid if the request matches the entity. | If-Match: "specific value" |
| If-Modified-Since | The request succeeds if the requested part is changed after the specified time, and returns a 304 code if it is not changed | If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| If-None-Match | If the content has not been changed return 304 code, the parameter is the Etag previously sent by the server, and the server responds to the Etag to determine whether or not it has changed | If-None-Match: "specific value" |
| If-Range | If the entity is unchanged, the server sends the missing portion of the client, otherwise it sends the entire entity. The parameter is also Etag | If-Range: "specific value" |
| If-Unmodified-Since | The request succeeds only if the entity has not been modified after the specified period of time | If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| Max-Forwards | Limit the amount of time the message is transmitted through the proxy and gateway | Max-Forwards: 10 |
| Pragma | Used to include instructions to implement specific | Pragma: no-cache |
| Proxy-Authorization | Authorization certificate for linking to the proxy | Proxy-Authorization: Authorization certificate linked to the proxy |
| Range | Only part of the requested entity is requested, specify the scope | Range: bytes=500-999 |
| Referer | The address of the previous page, followed by the currently requested page, i.e., the incoming path. | Referer: http://www.jsons.cn |
| TE | The transport encoding that the client is willing to accept and notifies the server of the acceptance of the tail-plus-header information. | TE: trailers,deflate;q=0.5 |
| Upgrade | Specify a transport protocol to the server for conversion (if supported). | Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11 |
| User-Agent | The content of the User-Agent contains information about the user making the request. | User-Agent: Mozilla/5.0 (Linux; X11) |
| Via | Notification of intermediate gateway or proxy server address, communication protocols | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Warning message about the message entity | Warn: 199 Miscellaneous warning |
| Header | Interpretation | Examples |
|---|---|---|
| Accept-Ranges | Indicates whether the server supports the specified range of requests and what type of segmented requests are supported. | Accept-Ranges: bytes |
| Age | Estimated time (in seconds, non-negative) to form a proxy cache from the originating server | Age: 12 |
| Allow | Valid request behavior for a network resource, return 405 if not allowed. | Allow: GET, HEAD |
| Cache-Control | Tells all caching mechanisms if caching is allowed and of which type | Cache-Control: no-cache |
| Content-Encoding | The type of return content compression encoding supported by the web server. | Content-Encoding: gzip |
| Content-Language | The language of the response body | Content-Language: en,zh |
| Content-Length | The length of the response body | Content-Length: 348 |
| Content-Location | Alternate alternate address to which the requested resource can be substituted | Content-Location: /index.htm |
| Content-MD5 | The MD5 checksum value of the returned resource | Content-MD5: MD5 checksum value |
| Content-Range | Byte position of this section in the entire response body | Content-Range: bytes 21010-47021/47022 |
| Content-Type | MIME type of the returned content | Content-Type: text/html; charset=utf-8 |
| Date | The time the original server message was sent | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| ETag | Current value of the entity tag of the request variable | ETag: "Current value of the entity tag of the request variable" |
| Expires | The date and time the response expired | Expires: Thu, 01 Dec 2010 16:00:00 GMT |
| Last-Modified | Last modification time of the requested resource | Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT |
| Location | Used to redirect the recipient to a non-requested URL to complete the request or identify a new resource | Location: http://www.jsons.cn |
| Pragma | Includes implementation-specific instructions that can be applied to any recipient in the response chain | Pragma: no-cache |
| Proxy-Authenticate | It indicates the authentication scheme and parameters that can be applied to the proxy at that URL. | Proxy-Authenticate: Basic |
| refresh | Applies to redirects or a new resource is created and redirected after 5 seconds (proposed by Netscape and supported by most browsers) |
Refresh: 5; url= http://www.jsons.cn
|
| Retry-After | If the entity is temporarily undesirable, the client is notified to try again after a specified time. | Retry-After: 120 |
| Server | web server software name | Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) |
| Set-Cookie | Set Http Cookie | Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1 |
| Trailer | Indicate that the header field is present at the end of the chunked transfer encoding | Trailer: Max-Forwards |
| Transfer-Encoding | File transfer encoding | Transfer-Encoding:chunked |
| Vary | Tells the downstream proxy whether to use a cached response or request from the original server | Vary: * |
| Via | Tells the proxy where the client response was sent | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Warns the entity of possible problems | Warning: 199 Miscellaneous warning |
| WWW-Authenticate | Indicates the authorization scheme that the client requesting entity should use | WWW-Authenticate: Basic |
HTTP request headers provide information about the request, response, or other sending entity, HTTP headers include the generic header, request header, response header and entity header four parts
Each header field consists of a domain name, a colon (:) and a domain value.
Generic headers: can be used for both requests and responses, and are associated with a transaction as a whole rather than a specific resource.
Request headers: allow the client to pass information about itself and the desired form of the response.
Response headers: the server and the response that conveys information about itself.
Entity Headers: Define information about the resource being transmitted, either in a request or a response.