python贴吧-python爬取贴吧帖子
一、介绍
我们常遇到一些很长的贴吧连载帖子想存到本地再看
此文就是运用python爬取指定百度贴吧的帖子并存到本地满足需求
环境:python2.7
目标网页:【长篇连载】剑网3的正史和野史——从头开始讲剧情故事
源码存放:源码github
本文参考:静觅博客python实战系列
二、页面的抓取
目标网页网址为https://tieba.baidu.com/p/2196794546
满足可以选择是否只看楼主的抓取我们点一下 只看楼主 并点一下后页的链接来获取只看楼主和翻页的参数
这时候可以看到只看楼主多出的参数 see_lz 和当前页的参数 pn
接下来定义一个DEMO类开始获取整个网页
# -*- coding:utf-8 -*-
import urllib
import urllib2
import re
class DEMO:
def __init__(self,baseUrl):
self.baseURL = baseUrl
def getPage(self):
url = baseURL
request = urllib2.Request(url)
response = urllib2.urlopen(request)
print response.read()
baseURL = 'https://tieba.baidu.com/p/2196794546?see_lz=1&pn=3'
demo = DEMO(baseURL)
demo.getPage()
运行结果:
爬取网页代码成功后我们完善一下代码,将只看楼主和页码提为参数
def __init__(self,baseUrl,seeLZ):
self.baseURL = baseUrl
self.seeLZ = '?see_lz=' +str(seeLZ)
self.tool = Tool()
def getPage(self,pageNum):
try:
url = self.baseURL+self.seeLZ + '&pn=' + str(pageNum)
request = urllib2.Request(url)
response = urllib2.urlopen(request)
return response.read().decode('utf-8')
except urllib2.URLError, e:
if hasattr(e,"reson"):
print u"链接失败,原因:",e.reason
return None
三、提取出想要的信息
打开目标网页审查元素（F12）
首先找到帖子标题的代码段:
【长篇连载】剑网3的正史和野史——从头开始讲剧情故事
我们将提取此
里的文本则正则表达式为:
(.*?)
接下来我们就可以写一个提取标题的方法:
def getTitle(self,title):
page = self.getPage(1)
pattern = re.compile('
(.*?)
',re.S)result = re.search(pattern,page)
if result:
return result.group(1).strip()
else:
return None
同理找到帖子页数的代码段,可得出提取页数的正则:
.*?(.*?)提取页数的方法:
def getPageNum(self,page):
page = self.getPage(1)
pattern = re.compile('
.*?(.*?)',re.S)result = re.search(pattern,page)
if result:
return result.group(1).strip()
else:
return None
接下来是我们主要目的,提取正文,正则为:
这个正则提取出来的只是div里面的文本内容,它还会包括了图片标签，换行符，段落符等的标签。所以我们还需处理一下。
这时候添加一个类利用正则将这些标签都替换掉
class Tool:
removeImg = re.compile('| {7}|')
removeAddr = re.compile('|')
replaceLine = re.compile('
|replaceTD = re.compile('
')replacePara = re.compile('
')replaceBR = re.compile('
')replaceBR = re.compile('
|
')
removeExtraTag = re.compile('<.*?')
def replace(self,x):
x = re.sub(self.removeImg,"",x)
x = re.sub(self.removeAddr,"",x)
x = re.sub(self.replaceLine," ",x)
x = re.sub(self.replaceTD," ",x)
x = re.sub(self.replacePara," ",x)
x = re.sub(self.replaceBR," ",x)
x = re.sub(self.removeExtraTag,"",x)
return x.strip()
初始化类后,我们可以写提取正文的方法:
def getContent(self,page):
pattern = re.compile('
items = re.findall(pattern,page)
contents = []
for item in items:
content = " " + self.tool.replace(item) + ' '
contents.append(content.encode('utf-8'))
return contents
四、写入文件,保存为txt
def setFileTitle(self,title):
if title is not None:
self.file = open(title + ".txt","w+")
else:
self.file = open(self.defaultTitle + ".txt","w+")
def writeData(self,contents):
for item in contents:
self.file.write(item)
五、完善代码
有了以上的方法作为基础，我们来写运行的方法:
def start(self):
indexPage = self.getPage(1)
pageNum = self.getPageNum(indexPage)
title = self.getTitle(indexPage)
self.setFileTitle(title)
if pageNum == None:
print "URL已失效,请重试"
return None
try:
print "该帖子共有" + str(pageNum) + "页"
for i in range(1,int(pageNum)+1):
print "正在写入第" + str(i) + "页数据"
page = self.getPage(i)
contents = self.getContent(page)
self.writeData(contents)
except IOError,e:
print "写入异常,原因" + e.message
finally:
print "写入任务完成"
此时完成的代码:
# -*- coding:utf-8 -*-
import urllib
import urllib2
import re
class Tool:
removeImg = re.compile('| {7}|')
removeAddr = re.compile('|')
replaceLine = re.compile('
|replaceTD = re.compile('
')replacePara = re.compile('
')replaceBR = re.compile('
')replaceBR = re.compile('
|
')
removeExtraTag = re.compile('<.*?')
def replace(self,x):
x = re.sub(self.removeImg,"",x)
x = re.sub(self.removeAddr,"",x)
x = re.sub(self.replaceLine," ",x)
x = re.sub(self.replaceTD," ",x)
x = re.sub(self.replacePara," ",x)
x = re.sub(self.replaceBR," ",x)
x = re.sub(self.removeExtraTag,"",x)
return x.strip()
class DEMO:
def __init__(self,baseUrl,seeLZ):
self.baseURL = baseUrl
self.seeLZ = '?see_lz=' +str(seeLZ)
self.tool = Tool()
def getPage(self,pageNum):
try:
url = self.baseURL+self.seeLZ + '&pn=' + str(pageNum)
request = urllib2.Request(url)
response = urllib2.urlopen(request)
return response.read().decode('utf-8')
except urllib2.URLError, e:
if hasattr(e,"reson"):
print u"链接失败,原因:",e.reason
return None
def getTitle(self,title):
page = self.getPage(1)
pattern = re.compile('
(.*?)
',re.S)result = re.search(pattern,page)
if result:
return result.group(1).strip()
else:
return None
def getPageNum(self,page):
page = self.getPage(1)
pattern = re.compile('
.*?(.*?)',re.S)result = re.search(pattern,page)
if result:
return result.group(1).strip()
else:
return None
def getContent(self,page):
pattern = re.compile('
items = re.findall(pattern,page)
contents = []
for item in items:
content = " " + self.tool.replace(item) + ' '
contents.append(content.encode('utf-8'))
return contents
def setFileTitle(self,title):
if title is not None:
self.file = open(title + ".txt","w+")
else:
self.file = open(self.defaultTitle + ".txt","w+")
def writeData(self,contents):
for item in contents:
self.file.write(item)
def start(self):
indexPage = self.getPage(1)
pageNum = self.getPageNum(indexPage)
title = self.getTitle(indexPage)
self.setFileTitle(title)
if pageNum == None:
print "URL已失效,请重试"
return None
try:
print "该帖子共有" + str(pageNum) + "页"
for i in range(1,int(pageNum)+1):
print "正在写入第" + str(i) + "页数据"
page = self.getPage(i)
contents = self.getContent(page)
self.writeData(contents)
except IOError,e:
print "写入异常,原因" + e.message
finally:
print "写入任务完成"
print u"请输入帖子代号"
baseURL = 'http://tieba.baidu.com/p/' + str(raw_input(u'http://tieba.baidu.com/p/'))
seeLZ = raw_input("是否只获取楼主发言,是输入1,否输入0 ")
demo = DEMO(baseURL,seeLZ)
demo.start()
好我们来运行一下试试:
到这里输入目标网页的代号:
整个运行过程:
好,这时候该目录下多了这个txt文件,打开看看
文本已经成功存到本地,到这里就成功了。