近期梳理python中的urllib/urllib2/httplib等相關庫的時候,發現以前對忽略了一些前端知識點,現在特地補一下。
經典的headers包含"Content-length","Content-type",和其他。結合查看Quick Reference to HTTPHeaders(http://www.cs.tut.fi/~jkorpela/http.html)獲取有用的HTTP頭列表以及它們的解釋意義。然而一堆英文不利於快速掌握這個知識點,好吧,直接來實例,一個key一個key的瞭解吧。打開百度首頁,F12走起,截圖如下:
HOST:
Specifies theInternet host and port number of the resource being requested. Obligatory inall HTTP/1.1 requests.網絡資源的主機和端口地址。
User-Agent [Request]
"Mozilla/5.0 (Windows NT 6.1; WOW64;rv:51.0) Gecko/20100101 Firefox/51.0"
Contains information about the user agent(client) originating the request。包含發起請求的用戶信息,通過這個參數,瀏覽器可以識別客戶使用的操作系統及版本、CPU 類型、瀏覽器及版本、瀏覽器渲染引擎、瀏覽器語言、瀏覽器插件等
我這裏是:
Mozilla/5.0,是基於 WebKit 的瀏覽器
Windows NT6.1 ,對應操作系統windows 7
Accept [Request]
Specifies which Internetmedia types are acceptable for the response and to assignpreferences to them.
表示可接受返回的數據類型,任何數據。jpg/gif就表示只能接受jpg/gif類型的數據.
Accept-Language[Request]
Specifies which natural languages areacceptable for the response and to assign preferences to them. Useful for language negotation. 定義頁面語言.
Accept-Encoding[Request]
Specifies which data formattranformations, confusingly called content(en)codings, such as compressionmechanisms, are acceptable for the response and to assign preferences to them.
定義數據壓縮格式.
Connection keep-alive表示不要立即斷掉我們的請求.