# coding:utf-8

 from selenium import webdriver

 import requests

 import sys

 import time

 from lxml import etree

 import cPickle

 import os

 # reload(sys)

 # sys.setdefaultencoding('utf-8')

 class Zhihu:

     def __init__(self,homeurl):

         self.homeurl = homeurl

     def save_session(self,session): #保存session，下次可直接使用，避免再次登录

         with open('session.txt','wb') as f:

             cPickle.dump(session, f)

             print "Cookies have been writed."

     def load_session(self):     #加载session

         with open('session.txt', 'rb') as f:

             s = cPickle.load(f)

         return s

     def GetCookies(self):       #初次登录用selenium模拟，并获得cookies

         browser = webdriver.Chrome()

         browser.get("https://www.zhihu.com/signin")

         browser.find_element_by_xpath("//main//div[2]/div[1]/form/div[1]/div[2]/div[1]/input").send_keys("")

         browser.find_element_by_xpath("//main//div[2]/div[1]/form/div[2]/div/div[1]/input").send_keys("xxxxxx")

         browser.find_element_by_xpath("//main//div[2]/div[1]/form/button").click()

         time.sleep(10)

         cookies = browser.get_cookies()

         browser.quit()

         return cookies

     def get_session(self):  #获取session

         s = requests.Session()

         if not os.path.exists('session.txt'):   #如果没有session，则创建一个，并且保存到文件中

             s.headers.clear()

             for cookie in self.GetCookies():

                 s.cookies.set(cookie['name'], cookie['value'])

             self.save_session(s)

         else:                                   #如果已存在session，则直接加载使用

             s = self.load_session()

         return s

     def Crawl(self):    #开始爬取

         s = self.get_session()

         html = s.get(self.homeurl).text

         html_tree = etree.HTML(html)

         items = html_tree.xpath('//main//div[1]/div[2]//div[@class="ContentItem AnswerItem"]/@data-zop')

         for item in items:

             content = eval(item)

             authorName = content['authorName']

             title = content['title']

             print authorName + "回答了：" + title

 zhihu = Zhihu('https://www.zhihu.com/')

 zhihu.Crawl()