很多网站，比如知乎、微博、豆瓣，都需要登录之后，才能浏览某些内容。所以想要爬取这类网站，必须先模拟登录。比较简单的方式是利用这个网站的 cookie。cookie 相当于是一个密码箱，里面储存了用户在该网站的基本信息。在一次登录之后，网站会记住你的信息，把它放到cookie里，方便下次自动登录。所以，要爬取这类网站的策略是：先进行一次手动登录，获取cookie，然后再次登录时，调用上一次登录得到的cookie，实现自动登录。
动态爬取
在爬取知乎某个问题的时候，需要将滑动鼠标滚轮到底部，以显示新的回答。静态的爬取方法无法做到这一点，可以引入selenium库来解决这一问题。selenium库模拟人浏览网站、进行操作，简单易懂。
scrapy.FormRequestlogin.py
class LoginSpider(scrapy.Spider):
name = 'login_spider'
start_urls = ['hin.com']def parse(self, response):
return [
scrapy.FormRequest.from_response(
response,# username和password要根据实际页面的表单的name字段进行修改
formdata={'username': 'your_username', 'password': 'your_password'},
callback=self.after_login)]def after_login(self, response):
# 登录后的代码
pass123456789101112131415
selenium登录获取cookie
get_cookie_by_selenium.py
import pickleimport timefrom selenium import webdriverdef get_cookies():
url = 'httest.com'
web_driver = webdriver.Chrome()
web_driver.get(url)
username = web_driver.find_element_by_id('login-email')
username.send_keys('username')
password = web_driver.find_element_by_id('login-password')
password.send_keys('password')
login_button = web_driver.find_element_by_id('login-submit')
login_button.click()
time.sleep(3)
cookies = web_driver.get_cookies()
web_driver.close()return cookiesif __name__ == '__main__':
cookies = get_cookies()
pickle.dump(cookies, open('cookies.pkl', 'wb'))12345678910111213141516171819202122232425
获取浏览器cookie(以Ubuntu的Firefox为例)
get_cookie_by_firefox.py
import sqlite3import pickledef get_cookie_by_firefox():
cookie_path = '/home/name/.mozilla/firefox/bqtvfe08.default/cookies.sqlite'
with sqlite3.connect(cookie_path) as conn:
sql = 'select name,value from moz_cookies where baseDomain="test.com"'
cur = conn.cursor()
cookies = [{'name': name, 'value': value} for name, value in cur.execute(sql).fetchall()]return cookiesif __name__ == '__main__':
cookies = get_cookie_from_firefox()
pickle.dump(cookies, open('cookies.pkl', 'wb'))12345678910111213141516
scrapy使用获取后的cookie
cookies = pickle.load(open('cookies.pkl', 'rb'))yield scrapy.Request(url, cookies=cookies, callback=self.parse)12
requests使用获取后的cookie
cookies = pickle.load(open('cookies.pkl', 'rb'))
s = requests.Session()for cookie in cookies:
s.cookies.set(cookie['name'], cookie['value'])1234
selenium使用获取后的cookie
from selenium import webdriver
cookies = pickle.load(open('cookies.pkl', 'rb'))
w = webdriver.Chrome()# 直接添加cookie会报错，下面是一种解决方案，可能有更好的# -- start --w.get('hww.test.com')
w.delete_all_cookies()# -- end --for cookie in cookies:
w.add_cookie(cookie)
