python爬虫是指对指定url中获取对我们有用的数据信息，通过代码实现数据的大量获取，只要你能通过浏览器访问的数据都可以通过爬虫获取。

实例：

爬取图片并下载，先准备好以下几点。

pip install requests
pip install BeautifulSoup4
pip install lxml

实现代码：

import os
import re
from uuid import uuid1
import requests
from bs4 import BeautifulSoup
from random import choice
# 获取随机请求头
def get_headers():
file = open('user_agent.txt', 'r')
user_agent_list = file.readlines()
user_agent = str(choice(user_agent_list)).replace('\n', '')
user_agent = 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:39.0) Gecko/20100101 Firefox/39.0' if len(
user_agent) < 10 else user_agent
headers = {
"User-Agent": user_agent,
}
return headers
# 负责下载图片
def download(src, end):
try:
headers = get_headers()
response = requests.get(src, headers=headers)
# 获取的文本实际上是图片的二进制文本
img = response.content
print(img)
path = "images/" + str(uuid1()) + end
# 将他拷贝到本地文件 w 写 b 二进制 wb代表写入二进制文本
with open(path, 'wb') as f:
f.write(img)
except Exception as e:
pass
# 负责请求页面
def requests_get(url):
try:
headers = get_headers()
# 请求页面
response = requests.get(url, headers=headers)
# 解析
soup = BeautifulSoup(response.text, 'lxml')
image_list = soup.find_all(attrs={"class": "img-responsive"})
for image in image_list[:-1]:
# 获取图片链接
src = image.attrs["data-backup"]
# 获取图片后缀
end = os.path.splitext(src)[1]
if src and end:
# 去除特殊字符
end = re.sub(r'[，。?？,/\\·]', '', end)
# 调用下载函数
download(src, end)
else:
pass
except Exception as e:
print(e)
pass
if __name__ == '__main__':
# 负责翻页
for page in range(1, 5):
url = 'https://www.doutula.com/photo/list/?page=%d' % page
requests_get(url)