Posted in Python onJune 13, 2018
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
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Python实现爬虫从网络上下载文档的实例代码
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