2018-05-29 21:05:42 +08:00
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from hashlib import sha1
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from urllib.parse import urljoin
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import pickle
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import re
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import requests
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import zlib
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from bs4 import BeautifulSoup
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from redis import Redis
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def main():
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# 指定种子页面
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base_url = 'https://www.zhihu.com/'
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seed_url = urljoin(base_url, 'explore')
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# 创建Redis客户端
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client = Redis(host='1.2.3.4', port=6379, password='1qaz2wsx')
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2018-05-30 11:42:00 +08:00
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# 设置用户代理(否则访问会被拒绝)
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2018-05-29 21:05:42 +08:00
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headers = {'user-agent': 'Baiduspider'}
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# 通过requests模块发送GET请求并指定用户代理
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resp = requests.get(seed_url, headers=headers)
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# 创建BeautifulSoup对象并指定使用lxml作为解析器
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soup = BeautifulSoup(resp.text, 'lxml')
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href_regex = re.compile(r'^/question')
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2018-05-30 11:42:00 +08:00
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# 将URL处理成SHA1摘要(长度固定更简短)
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hasher_proto = sha1()
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2018-05-29 21:05:42 +08:00
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# 查找所有href属性以/question打头的a标签
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for a_tag in soup.find_all('a', {'href': href_regex}):
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# 获取a标签的href属性值并组装完整的URL
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href = a_tag.attrs['href']
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full_url = urljoin(base_url, href)
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2018-05-30 11:42:00 +08:00
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# 传入URL生成SHA1摘要
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hasher = hasher_proto.copy()
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2018-05-29 21:05:42 +08:00
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hasher.update(full_url.encode('utf-8'))
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field_key = hasher.hexdigest()
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# 如果Redis的键'zhihu'对应的hash数据类型中没有URL的摘要就访问页面并缓存
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if not client.hexists('zhihu', field_key):
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html_page = requests.get(full_url, headers=headers).text
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# 对页面进行序列化和压缩操作
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zipped_page = zlib.compress(pickle.dumps(html_page))
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# 使用hash数据类型保存URL摘要及其对应的页面代码
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client.hset('zhihu', field_key, zipped_page)
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# 显示总共缓存了多少个页面
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print('Total %d question pages found.' % client.hlen('zhihu'))
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if __name__ == '__main__':
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main()
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