以爬取百度百科与python相关的1000个词条为例
https://baike.baidu.com/item/Python/407313
注：来源于https://www.imooc.com/learn/563
HTML下载器 (html_downloader.py)
from urllib import request
class HtmlDownloader(object):
def download(self, url):
if url is None:
return None
response = request.urlopen(url)
if response.getcode() != 200:
return None
return response.read().decode("utf-8")
Html解析器（html_parser.py）
from bs4 import BeautifulSoup
import re
from urllib import parse
class HtmlParser(object):
def _get_new_urls(self, page_url, soup):
new_urls = set()
links = soup.find_all('a', href = re.compile(r'/item/'))
for link in links:
new_url = link['href']
new_urls.add(parse.urljoin(page_url, new_url))
return new_urls
def _get_new_data(self, page_url, soup):
res_data = {}
title_node = soup.find('dd', class_ = "lemmaWgt-lemmaTitle-title").find("h1")
res_data['title'] = title_node.get_text()
summary_node = soup.find('div', class_ ="lemma-summary")
res_data['content'] = summary_node.get_text()
return res_data
def parser(self, page_url, html_cont):
if page_url is None or html_cont is None:
return
soup = BeautifulSoup(html_cont, 'html.parser', from_encoding = "utf-8")
new_urls = self._get_new_urls(page_url, soup)
new_data = self._get_new_data(page_url, soup)
return new_urls, new_data
url管理器 （url_manager.py）
class UrlManager(object):
def __init__(self):
self.new_urls = set()
self.old_urls = set()
def add_new_url(self, url):
if url is None:
return
if url not in self.new_urls and url not in self.old_urls:
self.new_urls.add(url)
def add_new_urls(self, urls):
if urls is None or len(urls) == 0:
return
for url in urls:
self.add_new_url(url)
def has_new_url(self):
if len(self.new_urls) != 0:
return len(self.new_urls)
else:
return None
def get_new_url(self):
new_url = self.new_urls.pop()
self.old_urls.add(new_url)
return new_url
html输出器 (html_outputer.py)
class HtmlOutputer(object):
def __init__(self):
self.datas = []
def collect_data(self, data):
if data is None:
return
self.datas.append(data)
def output_html(self):
f = open('putput.html', 'w', encoding = "utf-8")
f.write("<html>")
f.write("<body>")
f.write("<table>")
for data in self.datas:
f.write("<tr>")
f.write("<td> %s </td>" % data['url'])
f.write("<td> %s </td>" % data['title'])
f.write("<td> %s </td>" % data['summary'])
f.write("</tr>")
f.write("</table>")
f.write("</body>")
f.write("</html>")
f.close()
调度程序
from baike_apider import html_downloader, html_parser, url_manager, html_outputer
class SpiderMain(object):
def __init__(self):
self.urls = url_manager.UrlManager()
self.download = html_downloader.HtmlDownloader()
self.parser = html_parser.HtmlParser()
self.outputer = html_outputer.HtmlOutputer()
def craw(self, root_url):
count = 1
self.urls.add_new_url(root_url)
while self.urls.has_new_url():
try:
new_url = self.urls.get_new_url()
print('craw %d : %s' % (count, new_url))
html_cont = self.download.download(new_url)
new_urls, new_data = self.parser.parser(new_url, html_cont)
self.urls.add_new_urls(new_urls)
self.outputer.collect_data(new_data)
if count >= 2:
break
count = count + 1
except:
print('craw fail')
self.outputer.output_html()
if __name__ == '__main__':
root_url = 'https://baike.baidu.com/item/Python/407313'
obj_spider = SpiderMain()
obj_spider.craw(root_url)
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