目标分析：
目标：百度百科python词条相关词条网页 – 标题和简介
入口页：https://baike.baidu.com/item/Python/407313
URL格式：
– 词条页面URL：/item/xxxx
数据格式：
– 标题：
<dd class=”lemmaWgt-lemmaTitle-title”><h1>***</h1></dd>
– 简介：
<div class=”lemma-summary”>***</div>
页面编码：utf-8
爬虫主入口文件
spider_main.py
# coding:utf-8
import url_manager
import html_downloader
import html_parser
import html_outputerclass SpiderMain(object):
def __init__(self):
# url管理器
self.urls = url_manager.UrlManager()
# 下载器
self.downloader = html_downloader.HtmlDownloader()
# 解析器
self.parser = html_parser.HtmlParser()
# 输出控制器
self.outputer = html_outputer.HtmlOutputer() def craw(self, root_url):
# 记录当前爬取的是第几个url
count = 1
self.urls.add_new_url(root_url)
# 如果有待爬取的url就继续while循环
'''
while self.urls.has_new_url():
try:
new_url = self.urls.get_new_url()
print 'craw %d : %s' % (count, new_url)
# 下载url页面
html_cont = self.downloader.download(new_url)
# 进行url解析并获取url的数据
new_urls, new_data = self.parser.parse(new_url, html_cont)
# url解析及数据搜集
self.urls.add_new_urls(new_urls)
self.outputer.collect_data(new_data) if count >= 1000:
break
count = count + 1
except Exception as e:
print 'craw failed'
print e
'''
while self.urls.has_new_url():
new_url = self.urls.get_new_url()
print 'craw %d : %s' % (count, new_url)
# 下载url页面
html_cont = self.downloader.download(new_url)
# print html_cont
# 进行url解析并获取url的数据
new_urls, new_data = self.parser.parse(new_url, html_cont)
# url解析及数据搜集
self.urls.add_new_urls(new_urls)
self.outputer.collect_data(new_data) if count >= 10:
break
count = count + 1 # 输出到指定页面
self.outputer.output_html()if __name__ == "__main__":
root_url = "https://baike.baidu.com/item/Python/407313"
obj_spider = SpiderMain()
obj_spider.craw(root_url)
网页管理器
url_manager.py
# coding:utf-8class UrlManager(object):
def __init__(self):
# 要爬取的url
self.new_urls = set()
# 爬取过的url
self.old_urls = set() def add_new_url(self, url):
if url is None:
return
# 如果url不在要爬取的url里面也不在爬取过的url里面就添加进来
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):
return len(self.new_urls) != 0 def get_new_url(self):
new_url = self.new_urls.pop()
self.old_urls.add(new_url)
return new_url
网页下载器
html_downloader.py
# coding:utf-8import urllib2class HtmlDownloader(object):
def download(self, url):
if url is None:
return None response = urllib2.urlopen(url) if response.getcode() != 200:
return None return response.read()
网页分析器
html_parser.py
# coding:utf-8from bs4 import BeautifulSoup
import re
import urlparseclass HtmlParser(object): def _get_new_urls(self, page_url, soup):
# 得到所有的词条url
links = soup.find_all('a', href=re.compile(r"/item/.*"))
# print links
new_urls = set()
for link in links:
new_url = link['href']
new_full_url = urlparse.urljoin(page_url, new_url)
new_urls.add(new_full_url) return new_urls def _get_new_data(self, page_url, soup):
res_data = {}
# url
res_data['url'] = page_url # <dd class="lemmaWgt-lemmaTitle-title">
# <h1>Python</h1>
title_node = soup.find('dd', class_='lemmaWgt-lemmaTitle-title').find("h1")
res_data['title'] = title_node.get_text()
# <div class="lemma-summary" label-module="lemmaSummary">
summary_node = soup.find('div', class_="lemma-summary")
res_data['summary'] = summary_node.get_text() return res_data def parse(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
网页输出器
html_outputer.py
# coding:utf-8class HtmlOutputer(object):
def __init__(self):
self.datas = [] def collect_data(self, data):
if data is None:
return
self.datas.append(data) # ascii
def output_html(self):
fout = open('output.html', 'w') fout.write("<html>")
fout.write("<body>")
fout.write("<table>") for data in self.datas:
fout.write("<tr>")
fout.write("<td>%s</td>" % data['url'])
fout.write("<td>%s</td>" % data['title'].encode('utf-8'))
fout.write("<td>%s</td>" % data['summary'].encode('utf-8'))
fout.write("</tr>") fout.write("/table")
fout.write("/body")
fout.write("/html")
运行代码：
结果页面
