Python 爬虫的实践运用(1)--爬取百度百科的词条

参考地址:
Python开发简单爬虫
简介:
一共分为5个部分:

  1. spider_main #主程序
  2. UrlManager #url管理
  3. HtmlDownloader #网页下载器
  4. HtmlParser #网页解析器
  5. HtmlOutputer #解析结果输出

具体代码:
spider_main

#coding utf8

from BaiduBaike import html_download, html_parser, html_outputer, url_Manager

class SpiderMain(object):
    def __init__(self):
        self.urls = url_Manager.UrlManager()
        self.downloader = html_download.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 = count + 1
            except:
                print 'craw failed'            

        self.outputer.output_html()

if __name__ == '__main__':
    root_url = 'http://baike.baidu.com/view/21087\.htm'
    obj_spider = SpiderMain()
    obj_spider.craw(root_url)

UrlManager

#coding utf8

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):
        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

HtmlDownloader:

#coding utf8

import urllib2

class 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()

HtmlParser:

#coding utf8
from bs4 import BeautifulSoup
import re
import urlparse
from test.inspect_fodder import Tit

class HtmlParser(object):

    def _get_new_urls(self, page_url, soup):
        new_urls = set()
        #21087
        links = soup.find_all('a', href=re.compile(r'/view/\d+\.htm'))
        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 = {}

        res_data['url'] = page_url

        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['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

HtmlOutputer :

#coding utf8

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):
        fout = open('output.html','w')

        fout.write('<html>')
        fout.write('<meta charset="utf-8">')
        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>')    

结果展示:
Python 爬虫的实践运用(1)--爬取百度百科的词条_第1张图片

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