003.[python学习] 简单抓取豆瓣网电影信息程序

  1 #!/usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 
  4 
  5 import sys
  6 reload(sys)
  7 sys.setdefaultencoding(‘utf-8‘)  #解决编码问题
  8 
  9 
 10 """一个简单的从豆瓣网获取电影标签的示例,
 11 1. 首先获取所有标签以及它所对应的请求连接, 
 12    获取所有标签的请求链接是https://movie.douban.com/tag/?view=cloud
 13 2. 请求每个标签对应的链接获取该标签下所有电影信息
 14 """
 15 
 16 
 17 import urllib
 18 import urllib2
 19 import re
 20 import codecs
 21 # BeautifulSoup 用于解析html使用，本程序中使用lxml作为解析器
 22 from bs4 import BeautifulSoup
 23 
 24 
 25 # url正则表达式，用于将url分割为多个部分，对其中某些部分进行url编码使用
 26 URL_RGX = re.compile(r‘(?P<prefix>https?://)(?P<mid>[^?]+)(?P<has_key>\??)(?P<parms>[^?]*)‘)
 27 DOUBAN_TAG_URL = r‘https://movie.douban.com/tag/?view=cloud‘
 28 
 29 
 30 # url请求
 31 def get_request(url):
 32     # 对url特定部分进行编码
 33     matches = URL_RGX.match(url)
 34     if matches:
 35         dic = matches.groupdict()
 36         prefix = dic.get(‘prefix‘, ‘‘)
 37         mid = urllib.quote(dic.get(‘mid‘, ‘‘))
 38         has_key = dic.get(‘has_key‘, ‘‘)
 39         parms = dic.get(‘parms‘, ‘‘)
 40         if parms != ‘‘:
 41             tmp_dic = dict()
 42             for kv in parms.split(‘&‘):
 43                 k, v = kv, ‘‘
 44                 if ‘=‘ in kv:
 45                     k, v = kv.split(‘=‘, 1)
 46                 tmp_dic[k] = v
 47             parms = urllib.urlencode(tmp_dic)
 48         url = ‘{0}{1}{2}{3}‘.format(prefix, mid, has_key, parms)
 49     else:
 50         url = None
 51     if url:
 52         try:
 53             res = urllib.urlopen(url)
 54             if res and res.getcode() == 200:
 55                 return res.read()
 56         except Exception as e:
 57             pass
 58     return ‘‘
 59 
 60 
 61 # 获取所有标签信息，返回值为列表，列表中每个元素格式为(标签名, 标签url地址)
 62 def get_all_tags():
 63     all_tags = list()
 64     page_text = get_request(DOUBAN_TAG_URL)
 65     soup = BeautifulSoup(page_text, ‘lxml‘)
 66     tags = soup.find_all(‘a‘, attrs={‘class‘: ‘tag‘})
 67     for tag in tags:
 68         tag_name = tag.string
 69         # 将原有链接中的?focus=替换为空，替换后url为分页显示地址
 70         tag_url = tag[‘href‘].replace(‘?focus=‘, ‘‘)
 71         all_tags.append((tag_name, tag_url))
 72     return all_tags
 73 
 74 
 75 # 解析单个电影节点信息，返回电影信息字典
 76 def parse_movie_tag(movie_tag):
 77     # 下面15行代码好烂，下次改下它
 78     movie_title_tag = movie_tag.find(‘a‘, attrs={‘class‘: ‘title‘})
 79     movie_title = ‘无名电影‘
 80     movie_detail_url = ‘无链接‘
 81     if movie_title_tag:
 82         movie_title = movie_title_tag.string.strip()
 83         movie_detail_url = movie_title_tag[‘href‘].strip()
 84     # movie_detail_url = movie_tag.find(‘a‘, attrs={‘class‘: ‘title‘})[‘href‘]
 85     movie_desc_tag = movie_tag.find(‘div‘, attrs={‘class‘: ‘desc‘})
 86     movie_desc = ‘无描述信息‘
 87     if movie_desc_tag:
 88         movie_desc = movie_desc_tag.string.strip()
 89     movie_rating_nums_tag = movie_tag.find(‘span‘, attrs={‘class‘: ‘rating_nums‘})
 90     movie_rating_nums = ‘无评分信息‘
 91     if movie_rating_nums_tag:
 92         movie_rating_nums = movie_rating_nums_tag.string.strip()
 93     return {‘title‘: movie_title, ‘detail_url‘: movie_detail_url,
 94             ‘desc‘: movie_desc, ‘rating_nums‘: movie_rating_nums}
 95 
 96 
 97 # 获取当前页面中的电影信息节点
 98 def get_current_page_movies(page_url):
 99     page_text = get_request(page_url)
100     soup = BeautifulSoup(page_text, ‘lxml‘)
101     movies = soup.find_all(‘dd‘)
102     movie_info_lst = list()
103     for movie in movies:
104         # 将解析后的电影信息加入列表中
105         movie_info_lst.append(parse_movie_tag(movie))
106     return movie_info_lst
107 
108 
109 if __name__ == ‘__main__‘:
110     # 获取所有标签信息
111     all_tags = get_all_tags()
112     # 标签信息存到文件中
113     all_tags_file = codecs.open(‘all_tags_info.txt‘, ‘wb‘)
114     all_tags_file.write(‘标签名\t标签url地址\r\n‘)
115     for tag_name, tag_url in all_tags:
116         all_tags_file.write(‘{0}\t{1}\r\n‘.format(tag_name, tag_url))
117         all_tags_file.flush()
118     all_tags_file.close()
119     
120     # 获取每个标签下的所有电影
121     for tag_name, tag_url in all_tags:
122         movie_infos_file = codecs.open(tag_name + ‘.txt‘, ‘wb‘)
123         movie_infos_file.write(‘电影名\t标签名\t电影描述\t评分\t详细链接\r\n‘)
124         start = 0
125         while True:
126             target_url = ‘{base_url}?start={start}‘.format(base_url=tag_url,
127                                                            start=start)
128             movies = get_current_page_movies(target_url)
129             for movie in movies:
130                 title = movie.get(‘title‘, ‘‘)
131                 detail_url = movie.get(‘detail_url‘, ‘‘)
132                 desc = movie.get(‘desc‘, ‘‘)
133                 rating_nums = movie.get(‘rating_nums‘, ‘‘)
134                 movie_infos_file.write(‘{0}\t{1}\t{2}\t{3}\t{4}\r\n‘.format(title,
135                                                                           tag_name,
136                                                                           desc,
137                                                                           rating_nums,
138                                                                           detail_url))
139                 movie_infos_file.flush()
140             # 计算当前页电影总个数，因单页只显示15条信息，
141             # 所以如果单页电影数小于15则表示无后续页面，则跳出循环不再请求此分类
142             current_page_movies_count = len(movies)
143             if current_page_movies_count < 15:
144                 break
145             # 请求下一页标记数
146             start += current_page_movies_count
147         movie_infos_file.close()