python---cookie

Http is a stateless,so how to record the login information? use Cookie.There are some use of cookie in Python

1.get a cookie object and save it to a variable value

 1 import  urllib.request
 2 import http.cookiejar
 3 
 4 #declare a object to save the cookie
 5 cookie = http.cookiejar.CookieJar()
 6 #create a cookie processor
 7 handler = urllib.request.HTTPCookieProcessor(cookie)
 8 #build operer
 9 opener = urllib.request.build_opener(handler)
10 response = opener.open('http://www.baidu.com')
11 print(response.getcode())
12 for item in cookie:
13     print('Name = '+item.name)
14     print('Value = '+item.value)

2.get a cookie and save it to a file

 1 import urllib.request
 2 import http.cookiejar
 3 
 4 filename = 'cookie.txt'
 5 #declare a object to save cookie
 6 cookie = http.cookiejar.MozillaCookieJar(filename)
 7 #create a cookie processor
 8 handler = urllib.request.HTTPCookieProcessor(cookie)
 9 #build opener
10 opener = urllib.request.build_opener(handler)
11 response = opener.open('http://www.baidu.com')
12 print (response.getcode())
13 #write cookie into file named filename
14 cookie.save(ignore_discard=True,ignore_expires=True)

the interpretation of the parameter of save():
ignore_discard: save even cookies set to be discarded.
ignore_expires: save even cookies that have expired.

3.using a cookie saved in a file to visit a web site

 1 import urllib.request
 2 import http.cookiejar
 3 
 4 cookie = http.cookiejar.MozillaCookieJar()
 5 #read cookie from file
 6 cookie.load('cookie.txt',ignore_discard=True,ignore_expires=True)
 7 req = urllib.request.Request('http://www.baidu.com')
 8 opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cookie))
 9 request = opener.open(req)
10 print(request.getcode())