Python爬虫实例分析

import urllib.parse

import urllib.request

# params  CategoryId=808 CategoryType=SiteHome ItemListActionName=PostList PageIndex=3 ParentCategoryId=0 TotalPostCount=4000

def getHtml(url,values):

    user_agent='Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36'

    headers = {'User-Agent':user_agent}

    data = urllib.parse.urlencode(values)

    response_result = urllib.request.urlopen(url+'?'+data).read()

    html = response_result.decode('utf-8')

    return html

#获取数据

def requestCnblogs(index):

    print('请求数据')

    url = 'http://www.cnblogs.com/mvc/AggSite/PostList.aspx'

    value= {

         'CategoryId':808,

         'CategoryType' : 'SiteHome',

         'ItemListActionName' :'PostList',

         'PageIndex' : index,

         'ParentCategoryId' : 0,

        'TotalPostCount' : 4000

    }

    result = getHtml(url,value)

    return result

from bs4 import BeautifulSoup

import request

import re

#解析最外层

def blogParser(index):

  cnblogs = request.requestCnblogs(index)

  soup = BeautifulSoup(cnblogs, 'html.parser')

  all_div = soup.find_all('div', attrs={'class': 'post_item_body'}, limit=20)

  blogs = []

  #循环div获取详细信息

  for item in all_div:

      blog = analyzeBlog(item)

      blogs.append(blog)

  return blogs

#解析每一条数据

def analyzeBlog(item):

    result = {}

    a_title = find_all(item,'a','titlelnk')

    if a_title is not None:

        # 博客标题

        result["title"] = a_title[0].string

        # 博客链接

        result["href"] = a_title[0]['href']

    p_summary = find_all(item,'p','post_item_summary')

    if p_summary is not None:

        # 简介

        result["summary"] = p_summary[0].text

    footers = find_all(item,'div','post_item_foot')

    footer = footers[0]

    # 作者

    result["author"] = footer.a.string

    # 作者url

    result["author_url"] = footer.a['href']

    str = footer.text

    time = re.findall(r"发布于 .+? .+? ", str)

    result["create_time"] = time[0].replace('发布于 ','')

    comment_str = find_all(footer,'span','article_comment')[0].a.string

    result["comment_num"] = re.search(r'\d+', comment_str).group()

    view_str = find_all(footer,'span','article_view')[0].a.string

    result["view_num"] = re.search(r'\d+', view_str).group()

    return result

def find_all(item,attr,c):

    return item.find_all(attr,attrs={'class':c},limit=1)

import match

import os

import datetime

import json

def writeToTxt(list_name,file_path):

    try:

        #这里直接write item 即可，不要自己给序列化在写入，会导致json格式不正确的问题

        fp = open(file_path,"w+",encoding='utf-8')

        l = len(list_name)

        i = 0

        fp.write('[')

        for item in list_name:

            fp.write(item)

            if i

                fp.write(',\n')

            i += 1

        fp.write(']')

        fp.close()

    except IOError:

        print("fail to open file")

#def getStr(item):

#   return json.dumps(item).replace('\'','\"')+',\n'

def saveBlogs():

    for i in range(1,2):

        print('request for '+str(i)+'...')

        blogs = match.blogParser(i,5)

        #保存到文件

        path = createFile()

        writeToTxt(blogs,path+'/blog_'+ str(i) +'.json')

        print('第'+ str(i) +'页已经完成')

    return 'success'

def createFile():

    date = datetime.datetime.now().strftime('%Y-%m-%d')

    path = '/'+date

    if os.path.exists(path):

        return path

    else:

        os.mkdir(path)

        return path

result = saveBlogs()

print(result)