利用Python编写简单网络爬虫实例2
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://www.51testing.com/html/index.html”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 = ""
#
下载网页
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
#
获取网站入口版块的url
def get_board_url(self, url_set, include):
board_url_set = set() #
用于存放版块url
while len(url_set) > 0:
url = url_set.pop()
if re.findall(include, url):
board_url_set.add(url)
return board_url_set
#
入口版块
转换前URL：http://www.51testing.com/?action_category_catid_90.html
#
入口版块的子版块，转换前URL:http://www.51testing.com/?action-category-catid-91
#
转换后URL:http://www.51testing.com/html/90/category-catid-90.html
#
入口版块及其子版块url转换
def convert_board_url(self, url_set, if_sub=False):
tmp_url_set = set()
for url in url_set:
str1 = re.findall("[?].+[\d]+", url)
str2 = re.findall("[?].+[-|_]+", url) #
存放url中需要被替换的字符串
if str1[0][-2:].isdigit():
var = str1[0][-2:]
else:
var = str1[0][-1:]
replace_str = "html/"+var+"/category-catid-"
url_new = url.replace("".join(str2), replace_str)
if if_sub:
#
如果为子版块，需要添加.html结尾字符串
url_new
= url_new + ".html"
tmp_url_set.add(url_new)
return tmp_url_set
#
翻页页面，转换前URL：http://www.51testing.com/?action-category-catid-91-page-2
#
转换后URL:http://www.51testing.com/html/91/category-catid-91-page-2.html
#
转换子版块下子页面的url
def convert_sub_page_url(self, url_set):
tmp_url_set = set()
for url in url_set:
str1 = re.findall("[?].+-catid-[\d]+", url)
str2 = re.findall("[?].+[-|_]catid", url) #
存放url中需要被替换的字符串
if str1[0][-2:].isdigit():
var = str1[0][-2:]
else:
var = str1[0][-1:]
replace_str = "html/"+var+"/category-catid"
url_new = url.replace("".join(str2), replace_str)
url_new = url_new + ".html"
tmp_url_set.add(url_new)
return tmp_url_set
#
获取web页面url下的帖子url
def get_title_url(self, url_set, 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):
title_url_set.add(url)
return title_url_set
#
帖子，转换前URL：
#
转换后URL：http://www.51testing.com/?action-viewnews-itemid-1262758
#
转换帖子url：http://www.51testing.com/html/58/n-1262758.html
def conver_tilte_url(self, url_set):
tmp_url_set = set()
for url in url_set:
str1 = re.findall("[?].+[\d]+", url)
str2 = re.findall("[?].+[-|_]+", url) #
存放url中需要被替换的字符串
if str1[0][-2:].isdigit():
var = str1[0][-2:]
else:
var = str1[0][-1:]
replace_str = "html/"+var+"/n-"
url_new = url.replace("".join(str2), replace_str)
url_new = url_new + ".html"
tmp_url_set.add(url_new)
return tmp_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://www.51testing.com/html/index.html"
#
构造解析器
parser = MyHtmlParser(strict = False)
#
下载网页
print("program is downloading the frist url
page")
reptile = Reptile()
page = reptile.get_page(init_url, headers)
print("processing the first url page")
#
解析网页(获取url)
parser.feed(str(page))
#
获取入口版块url
pattern =
"http://www.51testing.com/[?]action[_|-]category[_|-]catid[_|-][\d]+[.]html"
include = re.compile(pattern)
board_url_set = reptile.get_board_url(parser.url_set,
include)
#
转换入口版块url
board_url_set_new =
reptile.convert_board_url(board_url_set)
#
获取每个入口版块下的子版块url("更多"页面)
pattern =
"http://www.51testing.com/[?]action[_|-]category[_|-]catid[_|-][\d]+$"
include = re.compile(pattern)
sub_board_url_set = set()
board_index = 1
for board_url in board_url_set_new:
page = reptile.get_page(board_url, headers)
parser.feed(str(page))
print("getting subboard urls in the %dth web board page" %
board_index)
tmp_url_set = reptile.get_board_url(parser.url_set,
include)
board_index = board_index + 1
sub_board_url_set = sub_board_url_set ^ tmp_url_set
#
转换入口版块的子版块的url
sub_board_url_set_new =
reptile.convert_board_url(sub_board_url_set, True)
#for url in sub_board_url_set_new:
#
print(url)
#
获取子版块的子页面url(点击数字页号翻页后的"页面",默认为前10页)
pattern =
"http://www.51testing.com/?action-category-catid-[\d]+-page-[\d]$"
include = re.compile(pattern)
sub_page_url_set = set()
board_index = 1
for sub_page_url in sub_board_url_set_new:
page = reptile.get_page(sub_page_url, headers)
parser.feed(str(page))
print("getting sub page urls in the %dth web page" %
board_index)
tmp_url_set = reptile.get_board_url(parser.url_set,
include)
board_index = board_index + 1
sub_page_url_set = sub_page_url_set ^ tmp_url_set
#for url in sub_page_url_set:
#
print(url)
#
转换子版块下的子页面url
sub_page_url_set =
reptile.convert_sub_page_url(sub_page_url_set)
#
获取所有web页面
web_page_set = sub_board_url_set_new ^
sub_page_url_set
#
获取页面文章
title_url_set = set()
board_index = 1
title_index = 1
for page_url in web_page_set:
page = reptile.get_page(page_url, headers)
parser.feed(str(page))
#
获取每个web页面下帖子url
pattern =
"http://www.51testing.com/[?]action-viewnews-itemid-[\d]+"
include = re.compile(pattern)
print("getting all title urls in the %dth web board" %
board_index)
tmp_url_set = reptile.get_title_url(parser.url_set,
include)
board_index = board_index + 1
title_url_set = title_url_set ^ tmp_url_set
title_url_set_new =
reptile.conver_tilte_url(title_url_set)
#
获取每篇文章下的目标url并写入文件
target_index = 1
title_index = 1
filepath = "d:/url2.txt"
for title_url in title_url_set_new:
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