SpiderMain类
SpiderMain是整个爬虫的驱动类
主要做了以下几件事 1.初始化url管理器,初始化html下载器,初始化html分析器,初始化输出器 2.实现craw方法
craw方法
它有一个参数root_url
首先将root_url加入到url管理器中,然后进行循环直到管理器中不再有新的url为止,然后输出收集的数据 在循环中首先得到新的url,然后用html下载器下载html页面,然后用parser对html内容进行解析得到其中的urls集合和数据 将新的urls加入到url管理器中,数据加入到输出器中这里用try语句输出错误信息
SpiderMain类代码
# coding:utf8
from pachong.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():
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 = count + 1
except Exception as e:
print(str(e))
self.outputer.output_html()
if __name__ == "__main__":
root_url = "https://baike.baidu.com/item/Python/407313"
obj_spider = SpiderMain()
obj_spider.craw(root_url)
UrlManager类
UrlManager是对url进行管理的类
它主要通过两个集合来对url进行管理new_urls中存放新的urlold_urls中存放就的url以防造成死循环
add_new_url方法
这个方法有一个参数url如果其为None则直接返回,如果url不在新url集合中也不在旧url集合中则将其加到新url的集合中
UrlManager代码
# 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类
该类是用来下载html页面的 这里因为还不熟悉requests库所以用的是urllib,这里用urlopen来请求对应url
HtmlDownloader代码
# coding:utf8
from urllib import request
class HtmlDownloader(object):
def download(self, url):
if url is None:
return None
res = request.urlopen(url)
if res.getcode() != 200:
return None
return res.read()
HtmlParser类
该类利用BeautifulSoup解析html
1.首先生成BeautifulSoup对象 2.利用1中对象解析出该页面的url,这里需要分析页面的结构,利用re模块进行正则表达式的匹配,最后利用urllib生成完整的url 3.利用1中对象解析出一张数据表
HtmlParser代码
# coding:utf8
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)
new_data = self._get_new_data(page_url, soup)
return new_urls, new_data
def _get_new_urls(self, page_url, soup):
new_urls = set()
# format /item/....
links = soup.find_all('a', href=re.compile(r'/item/'))
#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
def _get_new_data(self, page_url, soup):
res_data = {'url': page_url}
# <dd class="lemmaWgt-lemmaTitle-title"> <h1>Python</h1>
title_node = soup.find('dd', class_='lemmaWgt-lemmaTitle-title').find('h1')
res_data['title'] = title_node.get_text()
# <div class="lemma-summary" label-module="lemmaSummary">
summary_node = soup.find('div', class_='lemma-summary')
res_data['summary'] = summary_node.get_text()
return res_data
HtmlOutputer类
这是输出数据的类
目的是组织数据,注意编码
HtmlOutputer代码
# 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', encoding='utf-8')
fout.write('<html>')
fout.write("<head><meta http-equiv=\"content-type\" content=\"text/html;charset=utf-8\"></head>")
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()
转载于:https://www.cnblogs.com/tclan126/p/8811190.html
相关资源：基于 Python 实现微信公众号爬虫
