python爬取贴吧所有帖子-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('

|
')

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('

(.*?)

',re.S)

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('

|
')

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('

(.*?)

',re.S)

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。