python爬虫实战2-百度贴吧

# -*- coding:utf-8 -*-
import urllib
import urllib2
import re

# 处理页面标签类
class Tool:
# 去除img标签,7位长空格
removeImg = re.compile('<img.*?>| {7}|')
# 删除超链接标签
removeAddr = re.compile('<a.*?>|</a>')
# 把换行的标签换为\n
replaceLine = re.compile('<tr>|<div>|</div>|</p>')
# 将表格制表<td>替换为\t
replaceTD = re.compile('<td>')
# 把段落开头换为\n加空两格
replacePara = re.compile('<p.*?>')
# 将换行符或双换行符替换为\n
replaceBR = re.compile('<br><br>|<br>')
# 将其余标签剔除
removeExtraTag = re.compile('<.*?>')

def replace(self, x):
x = re.sub(self.removeImg, "", x)
x = re.sub(self.removeAddr, "", x)
x = re.sub(self.replaceLine, "\n", x)
x = re.sub(self.replaceTD, "\t", x)
x = re.sub(self.replacePara, "\n    ", x)
x = re.sub(self.replaceBR, "\n", x)
x = re.sub(self.removeExtraTag, "", x)
# strip()将前后多余内容删除
return x.strip()

# 百度贴吧爬虫类
class BDTB:
# 初始化，传入基地址，是否只看楼主的参数
def __init__(self, baseUrl, seeLZ, floorTag):
# base链接地址
self.baseURL = baseUrl
# 是否只看楼主
self.seeLZ = '?see_lz=' + str(seeLZ)
# HTML标签剔除工具类对象
self.tool = Tool()
# 全局file变量，文件写入操作对象
self.file = None
# 楼层标号，初始为1
self.floor = 1
# 默认的标题，如果没有成功获取到标题的话则会用这个标题
self.defaultTitle = u"百度贴吧"
# 是否写入楼分隔符的标记
self.floorTag = floorTag

# 传入页码，获取该页帖子的代码
def getPage(self, pageNum):
try:
# 构建URL
url = self.baseURL + self.seeLZ + '&pn=' + str(pageNum)
request = urllib2.Request(url)
response = urllib2.urlopen(request)
# 返回UTF-8格式编码内容
return response.read().decode('utf-8')
# 无法连接，报错
except urllib2.URLError, e:
if hasattr(e, "reason"):
print u"连接百度贴吧失败,错误原因", e.reason
return None

# 获取帖子标题
def getTitle(self, page):
# 得到标题的正则表达式
pattern = re.compile('<h1 class="core_title_txt.*?>(.*?)</h1>', re.S)
result = re.search(pattern, page)
if result:
# 如果存在，则返回标题
return result.group(1).strip()
else:
return None

# 获取帖子一共有多少页
def getPageNum(self, page):
# 获取帖子页数的正则表达式
pattern = re.compile('<li class="l_reply_num.*?</span>.*?<span.*?>(.*?)</span>', re.S)
result = re.search(pattern, page)
if result:
return result.group(1).strip()
else:
return None

# 获取每一层楼的内容,传入页面内容
def getContent(self, page):
# 匹配所有楼层的内容
pattern = re.compile('<div id="post_content_.*?>(.*?)</div>', re.S)
items = re.findall(pattern, page)
contents = []
for item in items:
# 将文本进行去除标签处理，同时在前后加入换行符
content = "\n" + self.tool.replace(item) + "\n"
contents.append(content.encode('utf-8'))
return contents

def setFileTitle(self, title):
# 如果标题不是为None，即成功获取到标题
if title is not None:
self.file = open(title + ".txt", "w+")
else:
self.file = open(self.defaultTitle + ".txt", "w+")

def writeData(self, contents):
# 向文件写入每一楼的信息
for item in contents:
if self.floorTag == '1':
# 楼之间的分隔符
floorLine = "\n" + str(
self.floor) + u"-----------------------------------------------------------------------------------------\n"
self.file.write(floorLine)
self.file.write(item)
self.floor += 1

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
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)
# 出现写入异常
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\n")
floorTag = raw_input("是否写入楼层信息，是输入1，否输入0\n")
bdtb = BDTB(baseURL, seeLZ, floorTag)
bdtb.start()