Python爬蟲入門-1

• 爬蟲:經過編寫程序,模擬瀏覽器上網,而後讓其去互聯網上爬取數據的過程.

• 爬蟲的分類:

  • 通用爬蟲:
  • 聚焦爬蟲:
  • 增量式:

• 反爬機制:

• 反反爬策略:

• robots.txt協議:聽從或者不聽從

 

requests模塊代碼編寫的流程:

• 指定url
• 發起請求
• 獲取響應對象中的數據
• 持久化存儲、

# 利用python爬蟲搜索
#1
url = 'https://www.sogou.com/'
#2.
response = requests.get(url=url)
#3.
page_text = response.text
#4.
with open('./sogou.html','w',encoding='utf-8') as fp:
    fp.write(page_text)

#需求：爬取搜狗指定詞條搜索後的頁面數據
import requests
url = 'https://www.sogou.com/web'
#封裝參數
wd = input('enter a word:')
param = {
    'query':wd
}
response = requests.get(url=url,params=param)

page_text = response.content
fileName = wd+'.html'
with open(fileName,'wb') as fp:
    fp.write(page_text)
    print('over')

#爬取百度翻譯結果
url = 'https://fanyi.baidu.com/sug'
wd = input('enter a word:')
data = {
    'kw':wd
}
response = requests.post(url=url,data=data)

print(response.json())

#response.text : 字符串
#.content : 二進制
#.json() : 對象

#爬取豆瓣電影分類排行榜 https://movie.douban.com/中的電影詳情數據
url = 'https://movie.douban.com/j/chart/top_list'
param = {
    "type": "5",
    "interval_id": "100:90",
    "action": '',
    "start": "60",
    "limit": "100",
}

movie_data = requests.get(url=url,params=param).json()

print(movie_data)

#需求：爬取國家藥品監督管理總局中基於中華人民共和國化妝品生產許可證相關數據http://125.35.6.84:81/xk/
#反爬機制:UA檢測  --> UA假裝
import requests
url = 'http://125.35.6.84:81/xk/itownet/portalAction.do?method=getXkzsList'
headers = {
    'User-Agent':'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36'
}
id_list = []
for page in range(1,11):
    data = {
        "on": "true",
        "page": str(page),
        "pageSize": "15",
        "productName": "",
        "conditionType": "1",
        "applyname": "",
        "applysn": "",
    }
    json_data = requests.post(url=url,data=data,headers=headers).json()
    for dic in json_data['list']:
        id = dic['ID']
        id_list.append(id)
    
detail_url = 'http://125.35.6.84:81/xk/itownet/portalAction.do?method=getXkzsById'
for id in id_list:
    detail_data = {
        'id':id
    }
    detail_json = requests.post(url=detail_url,data=detail_data,headers=headers).json()
    print(detail_json)

#爬取照片
url = 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=806201715,3137077445&fm=26&gp=0.jpg'
img_data = requests.get(url=url,headers=headers).content
with open('./xiaohua.jpg','wb') as fp:
    fp.write(img_data)

import urllib
url = 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=806201715,3137077445&fm=26&gp=0.jpg'
urllib.request.urlretrieve(url=url,filename='./123.jpg')

import re
string = '''fall in love with you
i love you very much
i love she
i love her'''

re.findall('^i.*',string,re.M)

#####################################################################
#匹配所有行
string1 = """細思極恐
你的隊友在看書
你的敵人在磨刀
你的閨蜜在減肥
隔壁老王在練腰
"""
re.findall('.*',string1,re.S)

import requests
import re
import urllib
import os
url = 'https://www.qiushibaike.com/pic/page/%d/?s=5170552'
# page = 1
headers = {
    'User-Agent':'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36'
}
if not os.path.exists('./qiutu'):
    os.mkdir('./qiutu')
    
start_page = int(input('enter a start pageNum:'))
end_page = int(input('enter a end pageNum:'))

for page in range(start_page,end_page+1):
    new_url = format(url%page)
#     print(new_url)
    page_text = requests.get(url=new_url,headers=headers).text
    img_url_list = re.findall('<div class="thumb">.*?<img src="(.*?)" alt=.*?</div>',page_text,re.S)
    for img_url in img_url_list:
        img_url = 'https:'+img_url
        imgName = img_url.split('/')[-1]
        imgPath = 'qiutu/'+imgName
        urllib.request.urlretrieve(url=img_url,filename=imgPath)
        print(imgPath,'下載成功!')
        
print('over!!!')

• bs4解析: 1.pii install bs4 2.pip install lxml

• 解析原理:

• 1.將即將要進行解析的源碼加載到bs對象
• 2.調用bs對象中相關的方法或屬性進行源碼中的相關標籤的定位
• 3.將定位到的標籤之間存在的文本或者屬性值獲取

import requests
from bs4 import BeautifulSoup
url = 'http://www.shicimingju.com/book/sanguoyanyi.html'
headers = {
    'User-Agent':'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36'
}
page_text = requests.get(url=url,headers=headers).text

soup = BeautifulSoup(page_text,'lxml')

a_list = soup.select('.book-mulu > ul > li > a')

fp = open('sanguo.txt','w',encoding='utf-8')
for a in a_list:
    title = a.string
    detail_url = 'http://www.shicimingju.com'+a['href']
    detail_page_text = requests.get(url=detail_url,headers=headers).text
    
    soup = BeautifulSoup(detail_page_text,'lxml')
    content = soup.find('div',class_='chapter_content').text
    
    fp.write(title+'\n'+content)
    print(title,'下載完畢')
print('over')
fp.close()