from crawler_test.html_downloader import UrlDownLoader
from crawler_test.html_outer import HtmlOuter
from crawler_test.html_parser import HtmlParser
from crawler_test.url_manager import UrlManager
# 爬虫主程序入口
class MainCrawler():
  def __init__(self):
    # 初始值，实例化四大处理器：url管理器，下载器，解析器，输出器
    self.urls = UrlManager()
    self.downloader = UrlDownLoader()
    self.parser = HtmlParser()
    self.outer = HtmlOuter()
  # 开始爬虫方法
  def start_craw(self, main_url):
    print('爬虫开始...')
    count = 1
    self.urls.add_new_url(main_url)
    while self.urls.has_new_url():
      try:
        new_url = self.urls.get_new_url()
        print('爬虫%d,%s' % (count, new_url))
        html_cOnt= self.downloader.down_load(new_url)
        new_urls, new_data = self.parser.parse(new_url, html_cont)
        # 将解析出的url放入url管理器，解析出的数据放入输出器中
        self.urls.add_new_urls(new_urls)
        self.outer.conllect_data(new_data)
        if count >= 10:# 控制爬取的数量
          break
        count += 1
      except:
        print('爬虫失败一条')
    self.outer.output()
    print('爬虫结束。')
if __name__ == '__main__':
  main_url = 'https://baike.baidu.com/item/Python/407313'
  mc = MainCrawler()
  mc.start_craw(main_url)

# URL管理器
class UrlManager():
  def __init__(self):
    self.new_urls = set() # 待爬取
    self.old_urls = set() # 已爬取
  # 添加一个新的url
  def add_new_url(self, url):
    if url is None:
      return
    elif url not in self.new_urls and url not in self.old_urls:
      self.new_urls.add(url)
  # 批量添加url
  def add_new_urls(self, urls):
    if urls is None or len(urls) == 0:
      return
    else:
      for url in urls:
        self.add_new_url(url)
  # 判断是否有url
  def has_new_url(self):
    return len(self.new_urls) != 0
  # 从待爬取的集合中获取一个url
  def get_new_url(self):
    new_url = self.new_urls.pop()
    self.old_urls.add(new_url)
    return new_url

from urllib import request
# 网页下载器
class UrlDownLoader():
  def down_load(self, url):
    if url is None:
      return None
    else:
      rt = request.Request(url=url, method='GET')   # 发GET请求
      with request.urlopen(rt) as rp:         # 打开网页
        if rp.status != 200:
          return None
        else:
          return rp.read()            # 读取网页内容

import re
from urllib import parse
from bs4 import BeautifulSoup
# 网页解析器，使用BeautifulSoup
class HtmlParser():
  # 每个词条中，可以有多个超链接
  # main_url指url公共部分，如“https://baike.baidu.com/”
  def _get_new_url(self, main_url, soup):
    # baike.baidu.com/
    # 计算机程序设计语言
    new_urls = set()
    # 解析出main_url之后的url部分
    child_urls = soup.find_all('a', href=re.compile(r'/item/(\%\w{2})+'))
    for child_url in child_urls:
      new_url = child_url['href']
      # 再拼接成完整的url
      full_url = parse.urljoin(main_url, new_url)
      new_urls.add(full_url)
    return new_urls
  # 每个词条中，只有一个描述内容，解析出数据（词条，内容）
  def _get_new_data(self, main_url, soup):
    new_datas = {}
    new_datas['url'] = main_url
    # 
计算机程序设计语言
...
    new_datas['title'] = soup.find('dd', class_='lemmaWgt-lemmaTitle-title').find('h1').get_text()
    # class="lemma-summary" label-module="lemmaSummary"...
    new_datas['content'] = soup.find('div', attrs={'label-module': 'lemmaSummary'},
                     class_='lemma-summary').get_text()
    return new_datas
  # 解析出url和数据（词条，内容）
  def parse(self, main_url, html_cont):
    if main_url is None or html_cont is None:
      return
    soup = BeautifulSoup(html_cont, 'lxml', from_encoding='utf-8')
    new_url = self._get_new_url(main_url, soup)
    new_data = self._get_new_data(main_url, soup)
    return new_url, new_data

# 输出器
class HtmlOuter():
  def __init__(self):
    self.datas = []
  # 先收集数据
  def conllect_data(self, data):
    if data is None:
      return
    self.datas.append(data)
    return self.datas
  # 输出为HTML
  def output(self, file='output_html.html'):
    with open(file, 'w', encoding='utf-8') as fh:
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write(
        '')
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write('')
      fh.write('')
      for data in self.datas:
        fh.write('')
        fh.write(''.format(data['url']))
        fh.write(''.format(data['title']))
        fh.write(''.format(data['content']))
        fh.write('')
      fh.write('
URL
词条
内容
{0}
{0}
{0}
')
      fh.write('')
      fh.write('')