Python 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

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