python的urllib四大模块_Python常用的内建模块4:urllib

urllib提供了一系列用于操作URL的功能

Get

urllib的request模块可以非常方便的抓取URL的内容, 也就是发送一个GET请求到制定的页面, 然后返回HTTP的响应:

例如, 对豆瓣的一个URLhttps://api.douban.com/v2/book/2129650进行抓取, 并返回响应:

from urllib import request

with request.urlopen('https://api.douban.com/v2/book/2129650') as f:

data = f.read()

print('Status:', f.status, f.reason)

for k, v in f.getheaders():

print('%s: %s' % (k, v))

print('Data:', data.decode('utf-8'))

可以看到HTTP响应的头和JSON数据：

Status: 200 OK

Server: nginx

Date: Tue, 26 May 2015 10:02:27 GMT

Content-Type: application/json; charset=utf-8

Content-Length: 2049

Connection: close

Expires: Sun, 1 Jan 2006 01:00:00 GMT

Pragma: no-cache

Cache-Control: must-revalidate, no-cache, private

X-DAE-Node: pidl1

Data: {"rating":{"max":10,"numRaters":16,"average":"7.4","min":0},"subtitle":"","author":["廖雪峰编著"],"pubdate":"2007-6",...}

如果我们要想模拟浏览器发送GET请求，就需要使用Request对象，通过往Request对象添加HTTP头，我们就可以把请求伪装成浏览器。例如，模拟iPhone 6去请求豆瓣首页：

from urllib import request

req = request.Request('http://www.douban.com/')

req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25')

with request.urlopen(req) as f:

print('Status:', f.status, f.reason)

for k, v in f.getheaders():

print('%s: %s' % (k, v))

print('Data:', f.read().decode('utf-8'))

这样豆瓣会返回适合iPhone的移动版网页：

...

Post

如果要以POST发送一个请求，只需要把参数data以bytes形式传入。

我们模拟一个微博登录，先读取登录的邮箱和口令，然后按照weibo.cn的登录页的格式以username=xxx&password=xxx的编码传入

from urllib import request, parse

print('Login to weibo.cn...')

email = input('Email: ')

passwd = input('Password: ')

login_data = parse.urlencode([

('username', email),

('password', passwd),

('entry', 'mweibo'),

('client_id', ''),

('savestate', '1'),

('ec', ''),

('pagerefer', 'https://passport.weibo.cn/signin/welcome?entry=mweibo&r=http%3A%2F%2Fm.weibo.cn%2F')

])

req = request.Request('https://passport.weibo.cn/sso/login')

req.add_header('Origin', 'https://passport.weibo.cn')

req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25')

req.add_header('Referer', 'https://passport.weibo.cn/signin/login?entry=mweibo&res=wel&wm=3349&r=http%3A%2F%2Fm.weibo.cn%2F')

with request.urlopen(req, data=login_data.encode('utf-8')) as f:

print('Status:', f.status, f.reason)

for k, v in f.getheaders():

print('%s: %s' % (k, v))

print('Data:', f.read().decode('utf-8'))

如果登录成功，我们获得的响应如下：

Status: 200 OK

Server: nginx/1.2.0

...

Set-Cookie: SSOLoginState=1432620126; path=/; domain=weibo.cn

...