Python爬虫包BeautifulSoup实例（三）


            一步一步构建一个爬虫实例，抓取糗事百科的段子

先不用beautifulsoup包来进行解析

第一步，访问网址并抓取源码





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 16:16:08

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 20:17:13



import urllib

import urllib2

import re

import os



if __name__ == '__main__':

  # 访问网址并抓取源码

  url = 'http://www.qiushibaike.com/textnew/page/1/?s=4941357'

  user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36'

  headers = {'User-Agent':user_agent}

  try:

    request = urllib2.Request(url = url, headers = headers)

    response = urllib2.urlopen(request)

    content = response.read()

  except urllib2.HTTPError as e:

    print e

    exit()

  except urllib2.URLError as e:

    print e

    exit()

  print content.decode('utf-8')



第二步，利用正则表达式提取信息 



首先先观察源码中，你需要的内容的位置以及如何识别 

然后用正则表达式去识别读取 

注意正则表达式中的 . 是不能匹配\n的，所以需要设置一下匹配模式。





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 16:16:08

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 20:17:13



import urllib

import urllib2

import re

import os



if __name__ == '__main__':

  # 访问网址并抓取源码

  url = 'http://www.qiushibaike.com/textnew/page/1/?s=4941357'

  user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36'

  headers = {'User-Agent':user_agent}

  try:

    request = urllib2.Request(url = url, headers = headers)

    response = urllib2.urlopen(request)

    content = response.read()

  except urllib2.HTTPError as e:

    print e

    exit()

  except urllib2.URLError as e:

    print e

    exit()



  regex = re.compile('<div class="content">.*?<span>(.*?)</span>.*?</div>', re.S)

  items = re.findall(regex, content)



  # 提取数据

  # 注意换行符，设置 . 能够匹配换行符

  for item in items:

    print item



第三步，修正数据并保存到文件中





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 16:16:08

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 21:41:32



import urllib

import urllib2

import re

import os



if __name__ == '__main__':

  # 访问网址并抓取源码

  url = 'http://www.qiushibaike.com/textnew/page/1/?s=4941357'

  user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36'

  headers = {'User-Agent':user_agent}

  try:

    request = urllib2.Request(url = url, headers = headers)

    response = urllib2.urlopen(request)

    content = response.read()

  except urllib2.HTTPError as e:

    print e

    exit()

  except urllib2.URLError as e:

    print e

    exit()



  regex = re.compile('<div class="content">.*?<span>(.*?)</span>.*?</div>', re.S)

  items = re.findall(regex, content)



  # 提取数据

  # 注意换行符，设置 . 能够匹配换行符

  path = './qiubai'

  if not os.path.exists(path):

    os.makedirs(path)

  count = 1

  for item in items:

    #整理数据，去掉\n,将<br/>换成\n

    item = item.replace('\n', '').replace('<br/>', '\n')

    filepath = path + '/' + str(count) + '.txt'

    f = open(filepath, 'w')

    f.write(item)

    f.close()

    count += 1



第四步，将多个页面下的内容都抓取下来





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 16:16:08

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 20:17:13



import urllib

import urllib2

import re

import os



if __name__ == '__main__':

  # 访问网址并抓取源码

  path = './qiubai'

  if not os.path.exists(path):

    os.makedirs(path)

  user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36'

  headers = {'User-Agent':user_agent}

  regex = re.compile('<div class="content">.*?<span>(.*?)</span>.*?</div>', re.S)

  count = 1

  for cnt in range(1, 35):

    print '第' + str(cnt) + '轮'

    url = 'http://www.qiushibaike.com/textnew/page/' + str(cnt) + '/?s=4941357'

    try:

      request = urllib2.Request(url = url, headers = headers)

      response = urllib2.urlopen(request)

      content = response.read()

    except urllib2.HTTPError as e:

      print e

      exit()

    except urllib2.URLError as e:

      print e

      exit()

    # print content



    # 提取数据

    # 注意换行符，设置 . 能够匹配换行符

    items = re.findall(regex, content)



    # 保存信息

    for item in items:

      #  print item

      #整理数据，去掉\n,将<br/>换成\n

      item = item.replace('\n', '').replace('<br/>', '\n')

      filepath = path + '/' + str(count) + '.txt'

      f = open(filepath, 'w')

      f.write(item)

      f.close()

      count += 1



  print '完成'



使用BeautifulSoup对源码进行解析





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 16:16:08

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 21:34:02



import urllib

import urllib2

import re

import os

from bs4 import BeautifulSoup



if __name__ == '__main__':

  url = 'http://www.qiushibaike.com/textnew/page/1/?s=4941357'

  user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36'

  headers = {'User-Agent':user_agent}

  request = urllib2.Request(url = url, headers = headers)

  response = urllib2.urlopen(request)

  # print response.read()

  soup_packetpage = BeautifulSoup(response, 'lxml')

  items = soup_packetpage.find_all("div", class_="content")



  for item in items:

    try:

      content = item.span.string

    except AttributeError as e:

      print e

      exit()



    if content:

      print content + "\n"



这是用BeautifulSoup去抓取书本以及其价格的代码 

可以通过对比得出到bs4对标签的读取以及标签内容的读取 

（因为我自己也没有学到这一部分，目前只能依葫芦画瓢地写）





# -*- coding: utf-8 -*-

# @Author: HaonanWu

# @Date:  2016-12-22 20:37:38

# @Last Modified by:  HaonanWu

# @Last Modified time: 2016-12-22 21:27:30

import urllib2

import urllib

import re 



from bs4 import BeautifulSoup 





url = "http://www.packtpub.com/all"

try:

  html = urllib2.urlopen(url) 

except urllib2.HTTPError as e:

  print e

  exit()



soup_packtpage = BeautifulSoup(html, 'lxml') 

all_book_title = soup_packtpage.find_all("div", class_="book-block-title") 



price_regexp = re.compile(u"\s+\$\s\d+\.\d+") 



for book_title in all_book_title: 

  try:

    print "Book's name is " + book_title.string.strip()

  except AttributeError as e:

    print e

    exit()

  book_price = book_title.find_next(text=price_regexp) 

  try:

    print "Book's price is "+ book_price.strip()

  except AttributeError as e:

    print e

    exit()

  print ""



以上全部为本篇文章的全部内容，希望对大家的学习有所帮助，也希望大家多多支持中文源码网。