Python爬虫爬取、解析数据操作示例

时间：2020-08-15 python爬虫查看: 925

本文实例讲述了Python爬虫爬取、解析数据操作。分享给大家供大家参考，具体如下：

爬虫当当网 http://search.dangdang.com/?key=python&act=input&page_index=1

获取书籍相关信息
面向对象思想
利用不同解析方式和存储方式

引用相关库

import requests
import re
import csv
import pymysql
from bs4 import BeautifulSoup
from lxml import etree
import lxml
from lxml import html

类代码实现部分

class DDSpider(object):
  #对象属性 参数 关键字 页数
  def __init__(self,key='python',page=1):
    self.url = 'http://search.dangdang.com/?key='+key+'&act=input&page_index={}'
    self.page = page
    self.headers = {'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36'}


  #私有对象方法
  def __my_url(self):
    my_url = []
    if self.page < 1:
      my_page = 2
    else:
      my_page = self.page+1
    #循环遍历每一页
    for i in range(1,my_page):
      my_url.append(self.url.format(i))
    return my_url

  #私有对象方法 请求数据
  def __my_request(self,url,parser_type):
    #循环遍历每一页
    response = requests.get(url=url,headers=self.headers)
    if response.status_code == 200:
      return self.__my_parser(response.text,parser_type)
    else:
      return None

  #私有对象方法 解析数据 1 利用正则 2 bs4 3 xpath
  def __my_parser(self,html,my_type=1):
    if my_type == 1:
      pattern = re.compile('<p.*?class=[\'\"]name[\'\"].*?name=[\'\"]title[\'\"].*?<a.*?title=[\'\"](.*?)[\'\"].*?href=[\'\"](.*?)[\'\"].*?name=[\'\"]itemlist-title[\'\"].*?<p class=[\'\"]detail[\'\"].*?>(.*?)</p>.*?<span.*?class=[\'\"]search_now_price[\'\"].*?>(.*?)</span>.*?<p.*?class=[\'\"]search_book_author[\'\"].*?><span>.*?<a.*?name=[\'\"]itemlist-author[\'\"].*?title=[\'\"](.*?)[\'\"].*?</span>',re.S)
      result = re.findall(pattern,html)
    elif my_type == 2:
      soup = BeautifulSoup(html,'lxml')
      result = []
      title_url = soup.find_all('a',attrs={'name':'itemlist-title'})
      for i in range(0,len(title_url)):
        title = soup.find_all('a',attrs={'name':'itemlist-title'})[i].attrs['title']
        url = soup.find_all('a',attrs={'name':'itemlist-title'})[i].attrs['href']
        price = soup.find_all('span',attrs={'class':'search_now_price'})[i].get_text()
        author = soup.find_all('a',attrs={'name':'itemlist-author'})[i].attrs['title']
        desc = soup.find_all('p',attrs={'class':'detail'})[i].get_text()
        my_tuple = (title,url,desc,price,author)
        result.append(my_tuple)
    else:
      html = etree.HTML(html)
      li_all = html.xpath('//div[@id="search_nature_rg"]/ul/li')
      result = []
      for i in range(len(li_all)):
        title = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="name"]/a/@title'.format(i+1))
        url = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="name"]/a/@href'.format(i+1))
        price = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]//span[@class="search_now_price"]/text()'.format(i+1))
        author_num = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="search_book_author"]/span[1]/a'.format(i+1))
        if len(author_num) != 0:
          #有作者 a标签
          author = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="search_book_author"]/span[1]/a[1]/@title'.format(i+1))
        else:
          #没有作者 a标签
          author = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="search_book_author"]/span[1]/text()'.format(i+1))
        desc = html.xpath('//div[@id="search_nature_rg"]/ul/li[{}]/p[@class="detail"]/text()'.format(i+1))
        my_tuple = (" ".join(title)," ".join(url)," ".join(desc)," ".join(price)," ".join(author))
        result.append(my_tuple)

    return result

  #私有对象方法 存储数据 1 txt 2 csv 3 mysql
  def __my_save(self,data,save_type=1):
    #循环遍历
    for value in data:
      if save_type == 1:
        with open('ddw.txt','a+',encoding="utf-8") as f:
          f.write('【名称】：{}【作者】：{}【价格】：{}【简介】：{}【链接】：{}'.format(value[0],value[4],value[3],value[2],value[1]))
      elif save_type == 2:
        with open('ddw.csv','a+',newline='',encoding='utf-8-sig') as f:
          writer = csv.writer(f)
          #转化为列表 存储
          writer.writerow(list(value))
      else:
        conn = pymysql.connect(host='127.0.0.1',user='root',passwd='',db='',port=3306,charset='utf8')
        cursor = conn.cursor()
        sql = ''
        cursor.execute(sql)
        conn.commit()
        cursor.close()
        conn.close()
  #公有对象方法 执行所有爬虫操作
  def my_run(self,parser_type=1,save_type=1):
    my_url = self.__my_url()
    for value in my_url:
      result = self.__my_request(value,parser_type)
      self.__my_save(result,save_type)

调用爬虫类实现数据获取

if __name__ == '__main__':
  #实例化创建对象
  dd = DDSpider('python',0)
  #参数 解析方式 my_run(parser_type,save_type)
  # parser_type 1 利用正则 2 bs4 3 xpath 
  #存储方式 save_type 1 txt 2 csv 3 mysql
  dd.my_run(2,1)

==总结一下: ==

1. 总体感觉正则表达式更简便一些 , 代码也会更简便 , 但是正则部分相对复杂和困难
2. bs4和xpath 需要对html代码有一定了解 , 取每条数据多个值时相对较繁琐

希望本文所述对大家Python程序设计有所帮助。

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