Python-爬虫 下载天涯论坛帖子

为了爬取的高效性，实现的过程中我利用了python的threading模块，下面是threads.py模块，定义了下载解析页面的线程，下载图片的线程以及线程池

import threading
import urllib2
import Queue
import re

thread_lock = threading.RLock()

#下载页面的一个函数，header中没有任何内容也可以顺利的下载，就省去了
def download_page(html_url):
try:
req = urllib2.Request(html_url)
response = urllib2.urlopen(req)
page = response.read()
return page
except Exception:
print ‘download %s failed’ % html_url
return None

#下载图片的一个方法，和上面的函数很像，只不过添加了一个文件头
#因为在测试的过程中发现天涯对于没有如下文件头的图片链接是不会返回正确的图片的
def download_image(image_url, referer):
try:
req = urllib2.Request(image_url)
req.add_header(‘Host’, ‘img3.laibafile.cn’)
req.add_header(‘User-Agent’, ‘Mozilla/5.0 (Windows NT 6.3; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0’)
req.add_header(‘Accept’, ‘image/png,image/*;q=0.8,*/*;q=0.5’)
req.add_header(‘Accept-Language’, ‘zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3’)
req.add_header(‘Referer’, referer)
req.add_header(‘Origin’, ‘http://bbs.tianya.cn’)
req.add_header(‘Connection’, ‘keep-alive’)
response = urllib2.urlopen(req)
image = response.read()
return image
except Exception:
print ‘download %s failed’ % image_url
return None

#下载和解析一个页面的线程类
class download_html_page(threading.Thread):
#name:线程的名字
#page_range:用户输入的页面范围
#page_contents:解析之后楼主的内容
#img_urls:解析之后楼主贴的图的链接
#html_url:输入的页面url
#first_page：第一次已经下载好的页面，主要是考虑效率，不重复下载
def __init__(self, name, page_range, page_contents, img_urls, html_url, first_page):
threading.Thread.__init__(self)
self.name = name
self.page_range = page_range
self.page_contents = page_contents
self.img_urls = img_urls

    self.html\_url = html\_url  self.first\_page = first\_page  #判断是不是楼主的内容  
def is\_louzhu(self, s):  result = re.search(r'<!-- <div class="host-ico">(.\*?)</div> -->', s, re.S)  return (result is not None)  #获得页面里属于楼主图片的url  
def get\_img\_url(self, s, page\_url):  #判断是不是楼主给其他用户的评论，如果是的话，直接过滤掉（本人从不看评论）  is\_louzhu\_answer = re.search(r'-{15,}<br>', s, re.S)  if is\_louzhu\_answer is None:  imgurl = re.findall(r'<img.\*?original="(?P<imgurl>.\*?)".\*?/><br>', s, flags = re.S)  url\_path = \[\]  for one\_url in imgurl:  self.img\_urls.put(one\_url + '|' + page\_url)  path = re.search('\\w+\\.jpg', one\_url).group(0)  url\_path.append('img/' + path)  segments = re.split(r'<img .\*?/><br>', s.strip())  content = segments\[0\].strip()  for i in range(len(url\_path)):  content += '\\n<img src = "' + url\_path\[i\] + '" />\\n<br>'  content += segments\[i+1\].strip()  return content  #解析夜歌页面  
def parse\_page(self, html\_page, page\_url):  html\_page.decode('utf-8')  Items = re.findall(r'<div class="atl-content">(?P<islouzhu>.+?)<div class="bbs-content.\*?">(?P<content>.+?)</div>', html\_page, re.S)  page\_content = ''  for item in Items:  if self.is\_louzhu(item\[0\]):  one\_div = self.get\_img\_url(item\[1\], page\_url)  if one\_div is not None:  page\_content += one\_div  return page\_content  def run(self):  while self.page\_range.qsize() > 0:  page\_number = self.page\_range.get()  page\_url = re.sub('-(\\d+?)\\.shtml', '-' + str(page\_number) + '.shtml', self.html\_url)  page\_content = ''  print 'thread %s is downloading %s' % (self.name, page\_url)  if page\_url == self.html\_url:  page\_content = self.parse\_page(self.first\_page, page\_url)  else:  page = download\_page(page\_url)  if page is not None:  page\_content = self.parse\_page(page, page\_url)  #thread\_lock.acquire()  #self.page\_contents\[page\_number\] = page\_content  #thread\_lock.release()  self.page\_contents.put(page\_content, page\_number)  self.img\_urls.put('finished')  

#下载图片的线程
class fetch_img(threading.Thread):
def __init__(self, name, img_urls, download_img):
threading.Thread.__init__(self)
self.name = name
self.img_urls = img_urls
self.download_img = download_img

def run(self):  while True:  message = self.img\_urls.get().split('|')  img\_url = message\[0\]  if img\_url == 'finished':  self.img\_urls.put('finished')  break  else:  thread\_lock.acquire()  if img\_url in self.download\_img:  thread\_lock.release()  continue  else:  thread\_lock.release()  print 'fetching image %s' % img\_url  referer = message\[1\]  image = download\_image(img\_url, referer)  image\_name = re.search('\\w+\\.jpg', img\_url).group(0)  with open(r'img\\%s' % image\_name, 'wb') as img:  img.write(image)  thread\_lock.acquire()  self.download\_img.add(img\_url)  thread\_lock.release()  

#定义了一个线程池
class thread_pool:
def __init__(self, page_range, page_contents, html_url, first_page):
self.page_range = page_range
self.page_contents = page_contents
self.img_urls = Queue.Queue()
self.html_url = html_url
self.first_page = first_page
self.download_img = set()

    self.page\_thread\_pool = \[\]  self.image\_thread\_pool = \[\]  def build\_thread(self, page, image):  for i in range(page):  t = download\_html\_page('page thread%d' % i, self.page\_range, self.page\_contents,  self.img\_urls, self.html\_url, self.first\_page)  self.page\_thread\_pool.append(t)  for i in range(image):  t = fetch\_img('image thread%d' % i, self.img\_urls, self.download\_img)  self.image\_thread\_pool.append(t)  def all\_start(self):  for t in self.page\_thread\_pool:  t.start()  for t in self.image\_thread\_pool:  t.start()  def all\_join(self):  for t in self.page\_thread\_pool:  t.join()  for t in self.image\_thread\_pool:  t.join()  

下面是主线程的代码：

# -*- coding: utf-8 -*-
import re
import Queue
import threads

if __name__ == ‘__main__’:
html_url = raw_input('enter the url: ')
html_page = threads.download_page(html_url)

max\_page = 0  
title = ''  
if html\_page is not None:  search\_title = re.search(r'<span class="s\_title"><span style="\\S+?">(?P<title>.+?)</span></span>', html\_page, re.S)  title = search\_title.groupdict()\['title'\]  search\_page = re.findall(r'<a href="/post-\\S+?-\\d+?-(?P<page>\\d+?)\\.shtml">(?P=page)</a>', html\_page, re.S)  for page\_number in search\_page:  page\_number = int(page\_number)  if page\_number > max\_page:  max\_page = page\_number  print 'title：%s' % title  
print 'max page number: %s' % max\_page  start\_page = 0  
while start\_page < 1 or start\_page > max\_page:  start\_page = input('input the start page number:')  end\_page = 0  
while end\_page < start\_page or end\_page > max\_page:  end\_page = input('input the end page number:')  page\_range = Queue.Queue()  
for i in range(start\_page, end\_page + 1):  page\_range.put(i)  page\_contents = {}  
thread\_pool = threads.thread\_pool(page\_range, page\_contents, html\_url, html\_page)  
thread\_pool.build\_thread(1, 1)  
thread\_pool.all\_start()  
thread\_pool.all\_join()  

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