問題描述：爬取拉勾網python、工作地在北京的相關職業（python，北京），將結果保存。

1.頁面分析：

因為拉勾網有反爬蟲機制，所以需要設置相應的請求信息，由於職位信息AJAX異步響應在頁面，所以直接訪問異步請求。

查看響應：

2.代碼：

#!/usr/bin/env/python
# coding:utf-8
import sys
import requests
import json
from bs4 import BeautifulSoup as bs


def main():
   # 拉勾網有反爬蟲機制
   # url=‘https://www.lagou.com/jobs/list_python?px=default&city=%E5%8C%97%E4%BA%AC#filterBox‘

   # AJAX請求
   url = ‘https://www.lagou.com/jobs/positionAjax.json?px=default&city=%E5%8C%97%E4%BA%AC&needAddtionalResult=false&isSchoolJob=0‘

   # 請求頭信息
   headers = {
      ‘Cookie‘: ‘SESSIONID=ABAAABAAAIAACBI386BBF2A4AF17A015A35A443275F849E; user_trace_token=20170823222931-7a66d0be-880f-11e7-8e7c-5254005c3644; LGUID=20170823222931-7a66d82d-880f-11e7-8e7c-5254005c3644; X_HTTP_TOKEN=efbd926a2120df44637a9a572dfe0f6e; _putrc=8582F8EBD102AF67; login=true; unick=%E6%8B%89%E5%8B%BE%E7%94%A8%E6%88%B71976; showExpriedIndex=1; showExpriedCompanyHome=1; showExpriedMyPublish=1; hasDeliver=0; TG-TRACK-CODE=search_code; Hm_lvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1503498572; Hm_lpvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1503502613; _ga=GA1.2.1002397109.1503498572; _gid=GA1.2.1028357858.1503498572; PRE_UTM=; PRE_HOST=; PRE_SITE=https%3A%2F%2Fwww.lagou.com%2Fjobs%2Flist_python%3Fpx%3Ddefault%26xl%3D%25E6%259C%25AC%25E7%25A7%2591%26city%3D%25E5%258C%2597%25E4%25BA%25AC; PRE_LAND=https%3A%2F%2Fwww.lagou.com%2Fjobs%2Flist_python%3Fpx%3Ddefault%26city%3D%25E5%258C%2597%25E4%25BA%25AC; LGSID=20170823233652-e3035a6a-8818-11e7-9fe3-525400f775ce; LGRID=20170823233656-e535491c-8818-11e7-9fe3-525400f775ce; SEARCH_ID=cc7603ed348d42898fdaec6b2dcb5e23; index_location_city=%E5%85%A8%E5%9B%BD‘,
      ‘Host‘: ‘www.lagou.com‘,
      ‘Origin‘: ‘https://www.lagou.com‘,
      ‘Referer‘: ‘https://www.lagou.com/jobs/list_python?px=default&city=%E5%8C%97%E4%BA%AC‘,
      ‘User-Agent‘: ‘Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36‘,
      ‘X-Anit-Forge-Code‘: ‘0‘,
      ‘X-Anit-Forge-Token‘: None,
      ‘X-Requested-With‘: ‘XMLHttpRequest‘
   }

   for pn in range(1, 31):
      # post參數
      post_form = {
         ‘kd‘: ‘python‘
      }
      post_form[‘first‘] = ‘false‘
      post_form[‘pn‘] = str(pn)
      if pn == 1:
         post_form[‘first‘] = ‘true‘

      # 獲取頁面
      result = requests.post(url, headers=headers, data=post_form)
      if result.status_code != 200:
         print(‘requet failed!‘)
         sys.exit()
      # print(result.content.decode(‘utf-8‘))
      file = ‘position/positions_page‘ + str(pn) + ‘.json‘
      try:
         result_json = result.json()
         # print(type(result_json))
         positions = result_json[‘content‘][‘positionResult‘][‘result‘]
         line = json.dumps(positions, ensure_ascii=False)
         with open(file, ‘w‘, encoding=‘utf8‘) as file:
            file.write(line)
            print(‘save ‘,file ,‘ successfully!‘)
      except Exception as e:
         print(‘save ‘, file, ‘ failed!‘)

if __name__ == ‘__main__‘:
   main()

3.運行結果：

將結果以json格式保存到文件中：

格式化顯示：

小爬拉勾網職位