python爬虫 压箱底的笔记

python爬虫，shigen 2023年5月27日整理的笔记，现在分享出来。

requests

pip install requests

beautifulSoup

参考文章：python 爬虫之 BeautifulSoup - 掘金

案例：爬取豆瓣top250榜电影名称

查看user-agent的小工具： 获取浏览器UA(userAgent)信息

import requests
from bs4 import BeautifulSoup

header = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36'}

url = 'https://movie.douban.com/top250'
response = requests.get(url, headers=header)
content = response.text

soup = BeautifulSoup(content, 'html.parser')
all_titles = soup.findAll('span', attrs={'class': 'title'})

for title in all_titles:
    print(title.get_text())

xpath

# html/xml解析
pip install lxml
from lxml import etree
tree = etree.HTML(content)
titles = tree.xpath('//*[@id="content"]/div/div[1]/ol//li/div/div[2]/div[1]/a/span[1]/text()')
print(titles)

cookie的处理

session = requests.session()
# 会携带上下文的cookie

防盗链

溯源，当前请求的上一级

案例中使用防盗链下载梨视频

# -*- encoding: utf-8 -*-
__date__ = '2023/05/28 10:33:03'

# this python shell is used to download video from pearvideo

import requests

url = 'https://www.pearvideo.com/video_1413858'
contant_id = url.split('/')[-1].split('_')[-1]
session = requests.Session()
session.get(url)

request_json_url = 'https://www.pearvideo.com/videoStatus.jsp?contId=1413858&mrd=0.051782001313967596'
headers = {'Referer': url}

res_json = session.get(url=request_json_url, headers=headers).json()
print(res_json)

systemTime = res_json['systemTime']
srcUrl = res_json['videoInfo']['videos']['srcUrl']
videoImg = res_json['videoInfo']['video_image']

videoUrl = srcUrl.replace(systemTime, 'cont-'+contant_id)
print(videoUrl, videoImg)

basePath = './files/' + contant_id 
import os

if not os.path.exists(basePath):
    os.makedirs(basePath)
# download video image
img_save_path = os.path.join(basePath, videoImg.split('/')[-1])
with open(img_save_path, 'wb') as file:
    file.write(session.get(videoImg).content)

# download video
video_save_path = os.path.join(basePath, videoUrl.split('/')[-1])
with open(video_save_path, 'wb') as file:
    file.write(session.get(videoUrl).content)

代理

通过代理ip访问真实的网站

国内免费的HTTP代理：2023年5月28日7时 国内最新免费HTTP代理IP - 站大爷 - 企业级高品质Http代理IP_Socks5代理服务器_免费代理IP

url = 'http://www.baidu.com'

import requests

proxy_ip = 'https:114.251.193.153:3128'

proxies = {
    "https": proxy_ip
}

response = requests.get(url=url, proxies=proxies)
# 直接爬取会出现乱码的问题
text = response.content.decode('utf-8')
print(text)

多线程

线程和进程的关系

线程：

进程：

多线程的创建和使用

from threading import Thread

def func(name):
    for i in range(100):
        print('func() called', i)

class MyThread(Thread):

    def run(self):
        for i in range(100):
            print('mythread func() called', i)

if __name__ == '__main__':
    # t = Thread(target=func, args=('shigen',))
    # t.start()
    
    t = MyThread()
    t.start()

    for i in range(100):
        print(i)

多进程

和多线程的API相似

from multiprocess import Process

线程池和进程池

from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor

def fn(name):
    for i in range(100):
        print(name, i)

if __name__ == "__main__":
    with ThreadPoolExecutor(50) as t:
        for i in range(100):
            t.submit(fn, name=f'线程执行{i}')
    print('all done')

获得线程运行结果信息：

# 创建一个包含5条线程的线程池
executor = ThreadPoolExecutor(max_workers=5)
lists = [1, 2, 3, 4, 5, 7, 8, 9, 10]
start_time = time.time()
result = [data for data in executor.map(action, lists)]
print(result)
executor.shutdown()
print(time.time() - start_time)

协程

当程序遇见了IO操作的时候，可以选择性的切换到其他任务上

在单线程的条件下

• 微观上：一个任务一个任务的切换，切换条件一般是IO操作
• 宏观上：多个任务一起异步执行

import asyncio

async def download(url):
    print(f'start downloading {url}')
    await asyncio.sleep(2)
    print('downloading finished')
    
    
async def main():
    urls = [
        'http://www.google.com',
        'http://www.baidu.com',
        'http://www.xiaomi.com'
    ]
    tasks = []
    for url in urls:
        tasks.append(asyncio.create_task(download(url)))
    await asyncio.wait(tasks)
    
if  __name__ == '__main__':
    asyncio.run(main())

http的携程

import asyncio

import aiohttp

basepath = './files/'

headers = {'Referer': 'https://xxxx.cn/'}

async def download(url):
    print(f'start downloading {url}')
    filename = url.split('/')[-2]
    async with aiohttp.ClientSession() as session:
        async with session.get(url=url, headers=headers) as resp:
            with open(basepath + filename, mode='wb') as f:
                f.write(await resp.content.read())
    print(f'downloading {url} finished')

async def main():
    urls = []
    tasks = []
    for url in urls:
        tasks.append(asyncio.create_task(download(url)))
    await asyncio.wait(tasks)

if __name__ == '__main__':
    asyncio.run(main())

selenium

自动化测试，打开浏览器，像人一样操作浏览器

pip install selenium

安装驱动

• 下载地址：chromedriver.storage.googleapis.com
• 参考文章：Python - 爬虫之Selenium - 掘金

解压到python解释器的位置，并重命名

tar -zxvf chromedriver_mac_arm64.zip
ll
which python3
mv chromedriver ~/opt/anaconda3/bin

测试

from selenium.webdriver import Chrome

# 创建浏览器对象
web = Chrome()

web.get('http://www.baidu.com')

print(web.get_window_size())
print(web.title)

可能遇到的问题： 解决mac无法打开chromedriver报错，由于无法验证开发人员，因此无法打开“ chromedriver”_webdriver mac 无法打开_奈暮希的博客-CSDN博客

爬取京东书籍

爬取京东上关于python的书籍信息，并保存成csv文件。

todo：部分页面的页面元素不一样，导致元素的查找存在问题。

from selenium import webdriver
from selenium.webdriver.common.by import By
import time
import pandas as pd

driver = webdriver.Chrome()

driver.get('https://www.jd.com/')
# 获取搜索框
search = driver.find_element(By.XPATH, '//*[@id="key"]')
# 获取查询按钮
button = driver.find_element(By.XPATH, '//*[@id="search"]/div/div[2]/button')
# 在搜索框中输入 Python
search.send_keys('Python')
# 点击查询按钮
button.click()
time.sleep(2)

# 获得商品
goods_list = driver.find_elements(By.XPATH, '//*[@id="J_goodsList"]/ul/li')
datas = []
for good in goods_list[:-1]:
    # 此处用css选择器比较保险
    img = good.find_element(By.CSS_SELECTOR, 'a > img').get_attribute('src')
    name = good.find_element(By.CSS_SELECTOR, 'div > div.p-name.p-name-type-2 > a > em').text
    prize = good.find_element(By.TAG_NAME, 'i').text
    url_element = good.find_element(By.CSS_SELECTOR, 'div > a')
    url = url_element.get_attribute('href')
    url_element.click()
    # 进入到新窗口
    driver.switch_to.window(driver.window_handles[-1])
    book_detail = driver.find_element(By.XPATH, '//*[@id="detail-tag-id-3"]/div[2]/div').text
    author_detail = driver.find_element(By.XPATH, '//*[@id="detail-tag-id-4"]/div[2]/div').text
    book_menu = driver.find_element(By.XPATH, '//*[@id="detail-tag-id-6"]/div[2]/div').text
    # 打开详情页获得内容简介、作者简介和目录
    print(img, name, prize, url)

    datas.append({
        'img': img,
        'name': name,
        'prize': prize,
        'url': url,
        'book_detail': book_detail,
        'author_detail': author_detail,
        'book_menu': book_menu,
    })
    # 关闭并切回到原来的窗口
    driver.close()
    driver.switch_to.window(driver.window_handles[0])
    
df = pd.DataFrame(datas)
df.to_csv('book_detail.csv', index=True, header=True)

暂时无法在飞书文档外展示此内容

无头浏览器

没有任何的界面，操作浏览器

# 创建配置对象
options = webdriver.ChromeOptions()
# 配置对象添加开启无界面模式的命令
options.add_argument('--headless')
# 配置对象添加禁用gpu的命令
options.add_argument('--disable-gpu')

# 实例化带有配置对象的driver对象
driver =Chrome(chrome_options=options)

代理ip

# 配置代理ip
options.add_argument('--proxy-server=http://150.138.253.70:808')

更换user-agent

# 更换User-Agent
options.add_argument('--user-agent=Opera/9.23 (X11; Linux x86_64; U; en)')

破解验证码

使用ocr或者超级鹰平台来识别验证码

超级鹰: 超级鹰验证码识别-专业的验证码云端识别服务,让验证码识别更快速、更准确、更强大

识别图片的点击操作

教程中讲的是使用selenium自动登录12306， 中国铁路12306网站