Python+MongoDB 爬取百度词条
本文是根据慕课网的内容的学习与总结：http://www.imooc.com/learn/563
程序采用的开发环境如下：
MongoDB版本：mongodb-3.4.1
Python版本：2.7
集成IDE：Pycharm
思维导图：ImindMap 9
先看一下数据库中的已经爬取（132条）的内容（词条链接，简介，标题）：
1、设计思路：
爬虫的一般步骤：确定要爬取的内容，分析网页结构，下载网页，解析网页，保存数据
本程序：主要分为以下几个模块
（1）URL管理器、（2）网页下载器、（3）网页解析器、（4）保存数据
2、编码：
（1）URL管理器：有两个set集合，set1保存尚未被下载解析的url，set2保存已被下载解析的url。每次从set1中取出url，进行下载解析，同时将新解析出来的url存入set1。
注：用set是避免爬虫的重复爬取
url_manager.py
#coding:utf-8
'''
date: 2017-8-12
description:Url管理类
'''
class UrlManager(object):
def __init__(self):
self.new_urls = set()
self.old_urls = set()
# 添加新的URL
def add_new_url(self, new_url):
if new_url is None:
return
if new_url not in self.new_urls and new_url not in self.old_urls:
self.new_urls.add(new_url)
# 添加多个Url
def add_new_urls(self, new_urls):
if new_urls is None or len(new_urls) == 0:
return
for url in new_urls:
self.add_new_url(url)
# 判断新Url集合是否为空
def has_new_url(self):
return len(self.new_urls) != 0
# 获取URL
def get_new_url(self):
new_url = self.new_urls.pop()
self.old_urls.add(new_url)
return new_url（2）.网页下载器：
这个比较简单，从URL管理器读取新的URL，进行下载即可，采用python2.7的内置库：urllib2
html_downloader.py
#coding:utf-8
'''
date:2017-8-12
description: 网页下载器
'''
import urllib2
class HtmlDownLoader(object):
def download(self, new_url):
if new_url is None:
return None
response = urllib2.urlopen(new_url)
if response.getcode() != 200:
return None
return response.read()（3）Url解析器：采用第三方库beautifulsoup4，
html_parser.py
#coding:utf-8
'''
date:2017-8-12
description: 网页解析类。采用BeautifulSoup进行解析
'''
import urlparse
from bs4 import BeautifulSoup
import re
class HtmlParser(object):
# 爬取本词条网页的所有相关连接URL
def get_new_urls(self, page_url, soup):
new_urls = set()
links = soup.find_all('a',href=re.compile(r'/item/.+[0-9]'))
for link in links:
new_url = link['href']
new_full_url = urlparse.urljoin(page_url,new_url)
new_urls.add(new_full_url)
# print link
return new_urls
# 根据标签获取要爬取的数据
def get_new_data(self, page_url, soup):
res_data = {}
#url
res_data['url'] = page_url
# class ="lemmaWgt-lemmaTitle-title" >
title_node = soup.find('dd',class_="lemmaWgt-lemmaTitle-title").find('h1')
res_data['title'] = title_node.get_text()
# class ="lemma-summary" label-module="lemmaSummary" >
summary_node = soup.find('div',class_="lemma-summary")
res_data['summary'] = summary_node.get_text()
return res_data
# 解析网页
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（4）存入数据库：数据库采用MongoDB，编码时需要安装pymongo
html_outputer.py
#coding:utf-8
'''
date: 2017-8-12
description:Url管理类
'''
import pymongo
class HtmlOutputer(object):
# 获取MongoDB的数据库连接
def getConnect(self):
connection = pymongo.MongoClient()
BaiduItem = connection.BaiduItem
BaiduItemConnection = BaiduItem.bitems
return BaiduItemConnection
def collect_data(self, data):
if data is None:
return
self.getConnect().insert_one(data)（5）程序入口：spider_main.py
#coding:utf-8
'''
date: 2017-8-12
description:Url管理类
'''
import html_downloader,html_parser,html_outputer,url_manager
class SpiderMain(object):
#初始化构造器
def __init__(self):
self.urls = url_manager.UrlManager()
self.downloader = 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.downloader.download(new_url)
new_urls, new_data = self.parser.parse(new_url, html_cont)
self.urls.add_new_urls(new_urls)
self.outputer.collect_data(new_data)
if count == 100:
break
count += 1
except:
print 'crawed failed'
# self.outputer.saveInfo()
if __name__ == '__main__':
root_url = "https://baike.baidu.com/view/21087.html"
obj_spider = SpiderMain()
obj_spider.craw(root_url)