http request process
ask
- The request contains four parts: the request method, the requested URL, the request header and the request body
- The request methods post and get are the most common
- The request URL is the url
- The common header information of the request header is as follows
- accept : request header field, used to specify which types of information the client can accept
- Accept-Language : Specifies the language type acceptable to the client
- Accept-encoding: Specifies the content encoding acceptable to the client
- Host : used to specify the host IP and port number for requesting resources
- cookie：
- referer : used to identify the page from which the request was sent
- user-agent : UA for short , a special service string that enables the server to identify the operating system version, browser and other information used by the client. Adding this information when doing a crawler can disguise it as a browser. If it is not added, it is likely to be identified. for reptiles
- Content-type : Internet media type
- The request body generally carries the form data in the post request. For the get request, the request body is empty.
response
- Returned by the server to the client, it is divided into three parts, the response status code, the response header, and the response body
- Response status code to understand by yourself
- response header
- Data : identifies when the response was generated
- last-modified : Specifies when the resource was last modified
- Content-type : the document type, specifying what is the data type returned
- Set-cookie : set cookies
- expires : Specifies the expiration time for the response
- The response body data is all in the response body