百度贴吧的数据抓取和分析（一）：指定条目帖子信息抓取

这个教程使用BeautifulSoup库爬取指定贴吧的帖子信息。

本教程的代码托管于github:　https://github.com/w392807287/spider_baidu_bar

数据分析部分请移步：

python版本：3.5.2

使用BeautifulSoup库获取网页信息

引入相关库：

from bs4 import BeautifulSoup
from urllib.request import urlopen
from urllib.error import HTTPError

这里使用python吧为例子，python吧的主页为：http://tieba.baidu.com/f?ie=utf-8&kw=python&fr=search，精简一点http://tieba.baidu.com/f?kw=python

获取BeautifulSoup对象：

url = "http://tieba.baidu.com/f?kw=python"
html = urlopen(url).read()
bsObj = BeautifulSoup(html, "lxml")

 这里将这一段进行封装，封装成一个传入url返回bs对象的函数：

def get_bsObj(url):
    '''
    返回给定url的beautifulsoup对象
    :param url:目标网址
    :return:beautifulsoup对象
    '''
    try:
        html = urlopen(url).read()
        bsObj = BeautifulSoup(html, "lxml")
        return bsObj
    except HTTPError as e:
        print(e)
        return None

 这个函数传入一个url，返回beautifulsoup对象，如果发生错误则打印出错误并返回空值。

 贴吧主页的处理

在贴吧主页中，包含了这个贴吧的大概信息，比如：关注量，主题数量，帖子数量。我们将这些信息汇总到一个文件。

获取主页bs对象：

bsObj_mainpage = get_bsObj(url)

 获取总页数：

last_page = int(bsObj_mainpage.find("a",{"class":"last pagination-item "})['href'].split("=")[-1])

 获取最后一页的页数是为了后面爬去帖子时越界。其中使用了beautifulsoup的find方法。

获取需要的信息并写入文件：

        red_text = bsObj_mainpage.findAll("span", {"class": "red_text"})
        subject_sum = red_text[0].get_text()  # 主题数
        post_sum = red_text[1].get_text()  # 帖子数
        follow_sum = red_text[2].get_text()  # 关注量

    with open('main_info.txt','w+') as f:
        f.writelines("统计时间: "+str(datetime.datetime.now())+"
")
        f.writelines("主题数:  "+subject_sum+"
")
        f.writelines("帖子数:  "+post_sum+"
")
        f.writelines("关注量:  "+follow_sum+"
")

 最后将这些步骤封装成一个函数，传入主页面的url，写入信息，返回最后一页的页码：

def del_mainPage(url):
    '''
    对主页面进行处理，返回最后页码
    :param url:目标主页地址
    :return:返回最后页码,int
    '''
    bsObj_mainpage = get_bsObj(url)
    last_page = int(bsObj_mainpage.find("a",{"class":"last pagination-item "})['href'].split("=")[-1])
    try:
        red_text = bsObj_mainpage.findAll("span", {"class": "red_text"})
        subject_sum = red_text[0].get_text()  # 主题数
        post_sum = red_text[1].get_text()  # 帖子数
        follow_sum = red_text[2].get_text()  # 关注量
    except AttributeError as e:
        print("发生错误:" + e + "时间:"+str(datetime.datetime.now()))
        return None
    with open('main_info.txt','w+') as f:
        f.writelines("统计时间: "+str(datetime.datetime.now())+"
")
        f.writelines("主题数:  "+subject_sum+"
")
        f.writelines("帖子数:  "+post_sum+"
")
        f.writelines("关注量:  "+follow_sum+"
")
    return last_page

 得到的结果：

统计时间: 2016-10-07 15:14:19.642933
主题数:  25083
帖子数:  414831
关注量:  76511

从页面中获取帖子地址

我们想要获取每个帖子的详细信息，就需要进入这个帖子，所以需要这个帖子的地址。比如：http://tieba.baidu.com/p/4700788764

这个url中，http://tieba.baidu.com是服务器地址，/p应该是路由中帖子（post)的对应,/4700788764即帖子的id。

我们观察贴吧首页会发现，每个帖子都是在一个块中。在浏览器中按Ｆ12观察其代码会发现，一个帖子所对应一个<li>标签，每个页面中有50个帖子（首页有广告贴可能不一样）。

其中<li>标签大概长这样：

<li class=" j_thread_list clearfix" data-field="{"id":4700788764,"author_name":"u6768u5175507","first_post_id":95008842757,"reply_num":2671,"is_bakan":null,"vid":"","is_good":null,"is_top":null,"is_protal":null,"is_membertop":null,"frs_tpoint":null}">
            <div class="t_con cleafix">
        
                    <div class="col2_left j_threadlist_li_left">
                <span class="threadlist_rep_num center_text" title="回复">2671</span>
            </div>
                <div class="col2_right j_threadlist_li_right ">
            <div class="threadlist_lz clearfix">
                <div class="threadlist_title pull_left j_th_tit ">
    
    
    <a href="/p/4700788764" title="恭喜《从零开始学Python》进入百度阅读平台【首页】新书推荐榜单" target="_blank" class="j_th_tit ">恭喜《从零开始学Python》进入百度阅读平台【首页】新书推荐榜单</a>
</div><div class="threadlist_author pull_right">
    <span class="tb_icon_author " title="主题作者: 杨兵507" data-field="{"user_id":625543823}"><i class="icon_author"></i><span class="frs-author-name-wrap"><a data-field="{"un":"u6768u5175507"}" class="frs-author-name j_user_card " href="/home/main/?un=%E6%9D%A8%E5%85%B5507&ie=utf-8&fr=frs" target="_blank">杨兵507</a></span><span class="icon_wrap  icon_wrap_theme1 frs_bright_icons "></span>    </span>
    <span class="pull-right is_show_create_time" title="创建时间">7-29</span>
</div>
            </div>
                            <div class="threadlist_detail clearfix">
                    <div class="threadlist_text pull_left">
                                <div class="threadlist_abs threadlist_abs_onlyline ">
            http://yuedu.baidu.com/ebook/ec1aa9f7b90d6c85ec3ac6d7?fr=index
        </div>

                    </div>

                    
<div class="threadlist_author pull_right">
        <span class="tb_icon_author_rely j_replyer" title="最后回复人: 杨兵小童鞋">
            <i class="icon_replyer"></i>
            <a data-field="{"un":"u6768u5175u5c0fu7ae5u978b"}" class="frs-author-name j_user_card " href="/home/main/?un=%E6%9D%A8%E5%85%B5%E5%B0%8F%E7%AB%A5%E9%9E%8B&ie=utf-8&fr=frs" target="_blank">杨兵小童鞋</a>        </span>
        <span class="threadlist_reply_date pull_right j_reply_data" title="最后回复时间">
            14:17        </span>
</div>
                </div>
                    </div>
    </div>
</li>

我们可以观察到<li>标签中的class=" j_thread_list clearfix" data-field="{"id":4700788764,"author_name":"u6768u5175507","first_post_id":95008842757,"reply_num":2671,"is_bakan":null,"vid":"","is_good":null,"is_top":null,"is_protal":null,"is_membertop":null,"frs_tpoint":null}"

根据class属性我们可以找到单个页面中所有的帖子：

posts = bsObj_page.findAll("li", {"class": "j_thread_list"})

 在data-field属性中我们可以得到：帖子ＩＤ，作者名称，回复数量，是否精品等信息。根据帖子ＩＤ我们可以得到帖子对应的url，不过下面<a>标签中直接给了。

我们获取链接并将其放入数组中：

post_info = post.find("a", {"class": "j_th_tit "})
urls.append("http://tieba.baidu.com" + post_info.attrs["href"])

 将上述代码打包，给出单页链接，返回此链接中所有帖子的url：

def get_url_from_page(page_url):
    '''
    对给定页面进行处理返回页面中帖子的url
    :param page_url: 页面链接
    :return: 页面中所有帖子的url
    '''
    bsObj_page = get_bsObj(page_url)
    urls = []
    try:
        posts = bsObj_page.findAll("li", {"class": "j_thread_list"})
    except AttributeError as e:
        print("发生错误:" + e + "时间:" + str(datetime.datetime.now()))
    for post in posts:
        post_info = post.find("a", {"class": "j_th_tit "})
        urls.append("http://tieba.baidu.com" + post_info.attrs["href"])
    return urls

处理每页的信息

上面我们得到了每页的地址，接下来我们处理每个帖子中的信息。我们需要在这页面中找到一些对我们有用的信息并将其存入csv文件中。

同样用这个地址举例：http://tieba.baidu.com/p/4700788764

首先，当打开这个链接是我们观察到的信息就是：帖子的标题，楼主名称，发帖时间，回复量等。

让我们观察一下这个页面的代码：

<div class="l_post j_l_post l_post_bright noborder " data-field="{"author":{"user_id":625543823,"user_name":"u6768u5175507","name_u":"%E6%9D%A8%E5%85%B5507&ie=utf-8","user_sex":2,"portrait":"8f0ae69da8e585b53530374925","is_like":1,"level_id":7,"level_name":"u8d21u58eb","cur_score":445,"bawu":0,"props":null},"content":{"post_id":95008842757,"is_anonym":false,"open_id":"tieba","open_type":"","date":"2016-07-29 19:10","vote_crypt":"","post_no":1,"type":"0","comment_num":0,"ptype":"0","is_saveface":false,"props":null,"post_index":0,"pb_tpoint":null}}">

 同样两个属性 class 和data-field，在data-field中包含了这个帖子的大部分信息：帖人id,发帖人昵称，性别，等级id，等级昵称，open_id,open_type,发帖日期等。

首先我们创建一个帖子对象，其中属性为帖子的信息，方法为将信息写入对应的csv文件：

class PostInfo:
    def __init__(self,post_id,post_title,post_url,reply_num,post_date,open_id,open_type,
                 user_name,user_sex,level_id,level_name):
        self.post_id = post_id
        self.post_title = post_title
        self.post_url = post_url
        self.reply_num = reply_num
        self.post_date = post_date
        self.open_id = open_id
        self.open_type = open_type
        self.user_name = user_name
        self.user_sex = user_sex
        self.level_id = level_id
        self.level_name = level_name

    def dump_to_csv(self,filename):
        csvFile = open(filename, "a+")
        try:
            writer = csv.writer(csvFile)
            writer.writerow((self.post_id,self.post_title,self.post_url,self.reply_num,self.post_date,self.open_id,
                             self.open_type,self.user_name,self.user_sex,self.level_id,self.level_name))
        finally:
            csvFile.close()

 然后我们通过find方法找到对应信息：

obj1 = json.loads(
bsObj.find("div", attrs={"class": "l_post j_l_post l_post_bright noborder "}).attrs['data-field'])
reply_num = bsObj.find("li", attrs={"class": "l_reply_num"}).span.get_text()
post_title = bsObj.find("h1", attrs={"class": "core_title_txt"}).get_text()

post_id = obj1.get('content').get('post_id')
post_url = url
post_date = obj1.get('content').get('date')
open_id = obj1.get('content').get('open_id')
open_type = obj1.get('content').get('open_type')
user_name = obj1.get('author').get('user_name')
user_sex = obj1.get('author').get('user_sex')
level_id = obj1.get('author').get('level_id')
level_name = obj1.get('author').get('level_name')

 创建对象，将其保存：

postinfo = PostInfo(post_id, post_title, post_url, reply_num, post_date, open_id, open_type, user_name,user_sex, level_id, level_name)
postinfo.dump_to_csv('post_info2.csv')

 其实不用通过对象保存，这只是个人想法。

将上面代码封装成处理每个帖子的函数：

def del_post(urls):
    '''
    处理传入url的帖子
    :param url:
    :return:
    '''
    for url in urls:
        bsObj = get_bsObj(url)
        try:
            obj1 = json.loads(
                bsObj.find("div", attrs={"class": "l_post j_l_post l_post_bright noborder "}).attrs['data-field'])
            reply_num = bsObj.find("li", attrs={"class": "l_reply_num"}).span.get_text()
            post_title = bsObj.find("h1", attrs={"class": "core_title_txt"}).get_text()
        except:
            print("发生错误:" + "---" + "时间:" + str(datetime.datetime.now()) + url)
            with open('error.txt', 'a+') as f:
                f.writelines("发生错误:" + "---" + "时间:" + str(datetime.datetime.now()) + url)
            return None
        post_id = obj1.get('content').get('post_id')
        post_url = url
        post_date = obj1.get('content').get('date')
        open_id = obj1.get('content').get('open_id')
        open_type = obj1.get('content').get('open_type')
        user_name = obj1.get('author').get('user_name')
        user_sex = obj1.get('author').get('user_sex')
        level_id = obj1.get('author').get('level_id')
        level_name = obj1.get('author').get('level_name')
        postinfo = PostInfo(post_id, post_title, post_url, reply_num, post_date, open_id, open_type, user_name,
                            user_sex, level_id, level_name)
        postinfo.dump_to_csv('post_info2.csv')
        del postinfo

得到的结果类似于：

98773024983,【轰动Python界】的学习速成高效大法,http://tieba.baidu.com/p/4811129571,2,2016-10-06 20:32,tieba,,openlabczx,0,7,贡士

组合使用上面的函数

首先，我们让用户输入需要爬去的贴吧的主页：

home_page_url = input("请输入要处理贴吧的主页链接")

 处理url：

bar_name = home_page_url.split("=")[1].split("&")[0]
pre_page_url = "http://tieba.baidu.com/f?kw=" + bar_name + "&ie=utf-8&pn="      #page_url 不包含页数的前缀

 处理主页：

all_post_num = del_mainPage(home_page_url)      #贴吧一共有多少条帖子

 让用户输入需要爬去的帖子数量：

del_post_num = int(input("请输入需要处理前多少条帖子："))     #指定需要处理的帖子数目

 最后：

if del_post_num > all_post_num:
    print("需要处理的帖子数大于贴吧帖子总数！")
else:
    for page in range(0,del_post_num,50):
        print("It's processing page : " + str(page))
        page_url = pre_page_url+str(page)
        urls = get_url_from_page(page_url)
        t = threading.Thread(target=del_post,args=(urls,))
        t.start()

主函数代码：

if __name__ == '__main__':
    #home_page_url = input("请输入要处理贴吧的主页链接")
    home_page_url = test_url
    bar_name = home_page_url.split("=")[1].split("&")[0]
    pre_page_url = "http://tieba.baidu.com/f?kw=" + bar_name + "&ie=utf-8&pn="      #page_url 不包含页数的前缀
    all_post_num = del_mainPage(home_page_url)      #贴吧一共有多少条帖子
    del_post_num = int(input("请输入需要处理前多少条帖子："))     #指定需要处理的帖子数目
    if del_post_num > all_post_num:
        print("需要处理的帖子数大于贴吧帖子总数！")
    else:
        for page in range(0,del_post_num,50):
            print("It's processing page : " + str(page))
            page_url = pre_page_url+str(page)
            urls = get_url_from_page(page_url)
            t = threading.Thread(target=del_post,args=(urls,))
            t.start()

 全部代码：

from bs4 import BeautifulSoup
from urllib.request import urlopen
from urllib.error import HTTPError
import json
import datetime
import csv
import threading

class PostInfo:
    def __init__(self,post_id,post_title,post_url,reply_num,post_date,open_id,open_type,
                 user_name,user_sex,level_id,level_name):
        self.post_id = post_id
        self.post_title = post_title
        self.post_url = post_url
        self.reply_num = reply_num
        self.post_date = post_date
        self.open_id = open_id
        self.open_type = open_type
        self.user_name = user_name
        self.user_sex = user_sex
        self.level_id = level_id
        self.level_name = level_name

    def dump_to_csv(self,filename):
        csvFile = open(filename, "a+")
        try:
            writer = csv.writer(csvFile)
            writer.writerow((self.post_id,self.post_title,self.post_url,self.reply_num,self.post_date,self.open_id,
                             self.open_type,self.user_name,self.user_sex,self.level_id,self.level_name))
        finally:
            csvFile.close()

def get_bsObj(url):
    '''
    返回给定url的beautifulsoup对象
    :param url:目标网址
    :return:beautifulsoup对象
    '''
    try:
        html = urlopen(url).read()
        bsObj = BeautifulSoup(html, "lxml")
        return bsObj
    except HTTPError as e:
        print(e)
        return None


def del_mainPage(url):
    '''
    对主页面进行处理，返回最后页码
    :param url:目标主页地址
    :return:返回最后页码,int
    '''
    bsObj_mainpage = get_bsObj(url)
    last_page = int(bsObj_mainpage.find("a",{"class":"last pagination-item "})['href'].split("=")[-1])
    try:
        red_text = bsObj_mainpage.findAll("span", {"class": "red_text"})
        subject_sum = red_text[0].get_text()  # 主题数
        post_sum = red_text[1].get_text()  # 帖子数
        follow_sum = red_text[2].get_text()  # 关注量
    except AttributeError as e:
        print("发生错误:" + e + "时间:"+str(datetime.datetime.now()))
        return None
    with open('main_info.txt','w+') as f:
        f.writelines("统计时间: "+str(datetime.datetime.now())+"
")
        f.writelines("主题数:  "+subject_sum+"
")
        f.writelines("帖子数:  "+post_sum+"
")
        f.writelines("关注量:  "+follow_sum+"
")
    return last_page

def get_url_from_page(page_url):
    '''
    对给定页面进行处理返回页面中帖子的url
    :param page_url: 页面链接
    :return: 页面中所有帖子的url
    '''
    bsObj_page = get_bsObj(page_url)
    urls = []
    try:
        posts = bsObj_page.findAll("li", {"class": "j_thread_list"})
    except AttributeError as e:
        print("发生错误:" + e + "时间:" + str(datetime.datetime.now()))
    for post in posts:
        post_info = post.find("a", {"class": "j_th_tit "})
        urls.append("http://tieba.baidu.com" + post_info.attrs["href"])
    return urls

def del_post(urls):
    '''
    处理传入url的帖子
    :param url:
    :return:
    '''
    for url in urls:
        bsObj = get_bsObj(url)
        try:
            obj1 = json.loads(
                bsObj.find("div", attrs={"class": "l_post j_l_post l_post_bright noborder "}).attrs['data-field'])
            reply_num = bsObj.find("li", attrs={"class": "l_reply_num"}).span.get_text()
            post_title = bsObj.find("h1", attrs={"class": "core_title_txt"}).get_text()
        except:
            print("发生错误:" + "---" + "时间:" + str(datetime.datetime.now()) + url)
            with open('error.txt', 'a+') as f:
                f.writelines("发生错误:" + "---" + "时间:" + str(datetime.datetime.now()) + url)
            return None
        post_id = obj1.get('content').get('post_id')
        post_url = url
        post_date = obj1.get('content').get('date')
        open_id = obj1.get('content').get('open_id')
        open_type = obj1.get('content').get('open_type')
        user_name = obj1.get('author').get('user_name')
        user_sex = obj1.get('author').get('user_sex')
        level_id = obj1.get('author').get('level_id')
        level_name = obj1.get('author').get('level_name')
        postinfo = PostInfo(post_id, post_title, post_url, reply_num, post_date, open_id, open_type, user_name,
                            user_sex, level_id, level_name)
        postinfo.dump_to_csv('post_info2.csv')
        # t = threading.Thread(target=postinfo.dump_to_csv,args=('post_info2.csv',))
        # t.start()
        del postinfo

test_url = "http://tieba.baidu.com/f?kw=python&ie=utf-8"

if __name__ == '__main__':
    #home_page_url = input("请输入要处理贴吧的主页链接")
    home_page_url = test_url
    bar_name = home_page_url.split("=")[1].split("&")[0]
    pre_page_url = "http://tieba.baidu.com/f?kw=" + bar_name + "&ie=utf-8&pn="      #page_url 不包含页数的前缀
    all_post_num = del_mainPage(home_page_url)      #贴吧一共有多少条帖子
    del_post_num = int(input("请输入需要处理前多少条帖子："))     #指定需要处理的帖子数目
    if del_post_num > all_post_num:
        print("需要处理的帖子数大于贴吧帖子总数！")
    else:
        for page in range(0,del_post_num,50):
            print("It's processing page : " + str(page))
            page_url = pre_page_url+str(page)
            urls = get_url_from_page(page_url)
            t = threading.Thread(target=del_post,args=(urls,))
            t.start()
    t.join()
            #del_post(urls)

以上　　

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