利用Python编写简单网络爬虫实例3
by:授客 QQ：1033553122
实验环境
python版本：3.3.5（2.7下报错
实验目的
获取目标网站“http://bbs.51testing.com/forum.php”中特定url，通过分析发现，目标url同其它url的关系如下
目标url存在子页面中的文章中，随机分布，我们要把它找出来
python脚本
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from urllib.request import *
import gzip, re
from io import BytesIO
from html.parser import HTMLParser
#
爬虫类
class Reptile:
"""to download web pages"""
def __init__(self):
self.url_set = set() #
用于存储已下载过的页面url
self.data = ""
#
下载页面
def get_page(self, url, headers):
request = Request(url, headers=headers)
request.add_header('Accept-encoding', 'gzip') #下载经过gzip方式压缩后的网页，减少网络流量
try:
response = urlopen(request) #
发送请求报文
if response.code == 200: #
请求成功
page = response.read() #
读取经压缩后的页面
if response.info().get("Content-Encoding") == "gzip":
page_data = BytesIO(page)
gzipper = gzip.GzipFile(fileobj = page_data)
self.data = gzipper.read()
else:
print("gzip unused")
self.data = page_data #
网页未采用gzip方式压缩，使用原页面
except Exception:
pass
self.url_set.add(url)
return self.data
#
获取论坛目标版块url
def get_forum_url(self, url_set, home, include):
forum_url_set = set() #
用于存放版块url
while len(url_set) > 0:
url = url_set.pop()
if re.findall(include, url):
#
读取的版块url通常是forum-53-1.html形势的
url = home + url
forum_url_set.add(url)
return forum_url_set
#
获取版块url下的帖子url
def get_title_url(self, url_set, home, include):
title_url_set = set() #
用于存放帖子url
while len(url_set) > 0:
url = url_set.pop()
if re.findall(include, url):
#
读取的帖子url通常是thread-1044711-1-1.html形式的
url = home + url
title_url_set.add(url)
return title_url_set
#
解析器类
class MyHtmlParser(HTMLParser):
def reset(self):
HTMLParser.reset(self) #
注意顺序
self.url_set = set()
def handle_starttag(self, tag, attrs):
#self.url = []
url_list = [value for key, value in attrs if "href" ==
key]
if url_list:
for url in url_list:
self.url_set.add(url)
##############测试################
#
添加头域，伪装浏览器访问网站,防止一些网站拒绝爬虫访问
headers = {'User-Agent':"Mozilla/5.0 (Windows NT 6.1;
WOW64; rv:33.0) Gecko/20100101 Firefox/33.0"}
init_url = "http://bbs.51testing.com/forum.php"
#
构造解析器
parser = MyHtmlParser(strict = False)
#
下载网页
page_number = 1
print("program is downloading the frist url
page")
reptile = Reptile()
page = reptile.get_page(init_url, headers)
print("processing the %dth url page" %
page_number)
#
解析网页(获取url)
parser.feed(str(page))
#
获取分类版块url
home = "http://bbs.51testing.com/"
#
分成多个变量来写，主要是为了书写方便，排版友好
pattern1 =
"forum-122-[1-9]|forum-243-[1-9]|forum-40-[1-9]|forum-63-[1-9]"
pattern2 =
"|forum-42-[1-9]|forum-53-[1-9]|forum-275-[1-9]|forum-140-[-9]"
pattern3 =
"|forum-138-[1-9]|forum-139-[1-9]|forum-141-[1-9]"
pattern = pattern1 + pattern2 + pattern3
include = re.compile(pattern)
forum_url_set = reptile.get_forum_url(parser.url_set, home,
include)
#
循环，获取每个分类版块下，1-10子版块的url(前10页)(翻页页面)
result_url_set = set()
forum_index = 1
for forum_url in forum_url_set:
page = reptile.get_page(forum_url, headers)
parser.feed(str(page))
print("getting the board urls in the %dth forum page" %
forum_index)
tmp_url_set = reptile.get_forum_url(parser.url_set, home,
include)
forum_index = forum_index + 1
result_url_set = result_url_set ^ tmp_url_set
title_url_set = set()
forum_index = 1
title_index = 1
for forum_url in result_url_set:
page = reptile.get_page(forum_url, headers)
parser.feed(str(page))
#
获取版块下的帖子url
pattern1 = "thread-[0-9]{7}-[0-9]{1}-[0-9]{1}[.]html|"
pattern2 = "thread-[0-9]{6}-[0-9]{1}-[0-9]{1}[.]html|"
pattern3 = "thread-[0-9]{7}-[0-9]{1}-[0-9]{2}[.]html|"
pattern4 = "thread-[0-9]{6}-[0-9]{1}-[0-9]{2}[.]html"
pattern = pattern1 + pattern2 + pattern3 + pattern4
include = re.compile(pattern)
print("getting all title urls in the %dth forum board" %
forum_index)
tmp_url_set = reptile.get_title_url(parser.url_set, home,
include)
forum_index = forum_index + 1
title_url_set = title_url_set ^ tmp_url_set
#
获取目标url
target_index = 1
title_index = 1
filepath = "d:/url.txt"
for title_url in title_url_set:
print("processing the %dth title url" % title_index)
page = reptile.get_page(title_url, headers)
parser.feed(str(page))
#
保存目标url
with open(filepath, "a") as f:
while len(parser.url_set) > 0:
url = parser.url_set.pop()
pattern =
"http://bbs.51testing.com/treasure/treasure.php[?]trenum=[0-9]{5}"
include = re.compile(pattern)
flag = re.findall(include, url)
if flag:
print("find target! saving the %dth target url in the %dth title
page" % (target_index, title_index))
f.write("the %dth url: %s" % (target_index, url))
target_index = target_index + 1
f.write("\n")
title_index = title_index + 1
print("complete")
结果：
声明：仅供学习研究使用，请勿用于其它非法用途