Python实现爬虫从网络上下载文档的实例代码

最近在学习Python，自然接触到了爬虫，写了一个小型爬虫软件，从初始Url解析网页，使用正则获取待爬取链接，使用beautifulsoup解析获取文本，使用自己写的输出器可以将文本输出保存，具体代码如下：

Spider_main.py

# coding:utf8
from baike_spider import url_manager, html_downloader, html_parser, html_outputer
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():
      print("self.urls.has %s" % self.urls.new_urls)
      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 == 1000:
          break
        count = count + 1
      except:
        print("craw failed")
    self.outputer.output_html()
    self.outputer.output_txt()
if __name__ == '__main__':
  root_url = "http://www.shushu8.com/jiangnan/longzu2qianzhuan/1"
  obj_spider = SpiderMain()
  obj_spider.craw(root_url)

url_manager.py

class UrlManager(object):
  def __init__(self):
    self.new_urls = set()
    self.old_urls = set()
  def add_new_url(self, url):
    print(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 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)
    # print('new url is %s' % new_url)
    return new_url
  def add_new_urls(self, urls):
    print("add_new_urls %s" % urls)
    if urls is None or len(urls) == 0:
      return
    for url in urls:
      self.add_new_url(url)
      print(url)

html_parser.py

import re
import urllib.parse
from bs4 import BeautifulSoup
class HtmlParser(object):
  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)
    print("parse new_urls %s" % new_urls)
    new_data = self._get_new_data(page_url, soup)
    return new_urls, new_data
  def _get_new_data(self, page_url, soup):
    res_data = {}
    res_data['url'] = page_url
    print(page_url)
    title_node = soup.find(class_="title").find("h1")
    print(title_node.get_text())
    res_data['title'] = title_node.get_text()
    print("_get_new_data")
    summary_node = soup.find('pre')
    print(summary_node.get_text())
    res_data['summary'] = summary_node.get_text()
    return res_data
  def _get_new_urls(self, page_url, soup):
    new_urls = set()
    links = soup.find_all('a', href=re.compile(r"/jiangnan/"))
    print(links)
    for link in links:
      new_url = link['href']
      new_full_url = urllib.parse.urljoin(page_url, new_url)
      new_urls.add(new_full_url)
      # print(new_full_url)
    return new_urls

html_downloader.py

import urllib.request
class HtmlDownloader(object):
  def download(self, url):
    if url is None:
      return None
    response = urllib.request.urlopen(url)
    if response.getcode() != 200:
      return None
    return response.read()

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_txt(self):
    fout = open('output.txt', 'w', encoding='utf-8')
    for data in self.datas:
      fout.write('%s \n' % data['title'])
      fout.write('%s \n' % data['summary'])
  def output_html(self):
    fout = open('output.html', 'w', encoding='utf-8')
    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'])
      fout.write('<td>%s</td>' % data['summary'])
      fout.write('</tr>')
    fout.write('</table>')
    fout.write('</body>')
    fout.write('</html>')
    fout.close()

总结

以上所述是小编给大家介绍的Python实现爬虫从网络上下载文档的实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！