爬取百度百科N个页面的数据

目标：百度百科Python词条相关词条网页 - 标题和简介

入口页：http://baike.baidu.com/item/Python

URL格式：

• 词条页面URL：/item/Python

数据格式：

• 标题
  

  Python

• 简介
  

页面编码：

• UTF-8

调度程序 spider_main.py

#coding:utf8
import html_downloader, html_parser, html_outputer,url_manager

class SpiderMain(object):
    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 == 10:
                    break
                count+=1
                
            except:
                print 'craw failed'
            
        self.outputer.output_html()


if __name__=="__main__":
    root_url = "http://baike.baidu.com/item/Python"
    obj_spider = SpiderMain()
    obj_spider.craw(root_url)

URL管理器 url_manager.py

#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

HTML下载器 html_downloader.py

#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()

HTML解析器 html_parser.py

#coding:utf8
from bs4 import BeautifulSoup
import re
import urlparse


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_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
        
        #
Python
        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

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

        for data in self.datas:
            fout.write("")
            fout.write("" % data['url'])
            fout.write("" % data['title'].encode('utf-8'))
            fout.write("" % data['summary'].encode('utf-8'))
            fout.write("")


        fout.write("
%s
%s
%s
")
        fout.write("")
        fout.write("")

        fout.close()