无法替换UserAgent求助：用fake_useragent仍显示python-requests/2.28.1

问题出在请求头的字段名上——你写的是'user_agent'，但HTTP标准的User-Agent字段名是**'User-Agent'**（大小写敏感）。requests库只会识别正确的字段名，不正确的字段会被忽略，导致请求依然使用默认的python-requests/2.28.1。

修正后的代码 #

from fake_useragent import UserAgent
import requests
from bs4 import BeautifulSoup

user = UserAgent()
# 修正字段名为正确的'User-Agent'
header = {'User-Agent': user.random}

link = "url"
response = requests.get(link, headers=header).text
soup = BeautifulSoup(response, 'lxml')
block = soup.find('div', id='tool_padding')

check_js = block.find('div', id="javascript_check")
check_flash = block.find('div', id="flash_version")
check_ua = block.find('div', id="user_agent").text

result_js = check_js.find_all('span')[1].text
result_flash = check_flash.find_all('span')[1].text

print(f'js: {result_js}\nflash: {result_flash}\n{check_ua}')

额外注意事项 #

• 如果fake_useragent偶尔出现UA生成失败的情况，可以添加备用UA：

  header = {'User-Agent': user.random or 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36'}
  

• 若仍有问题，可手动指定UA列表来生成，避免fake_useragent的网络依赖：

  ua_list = [
      'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36',
      'Mozilla/5.0 (Macintosh; Intel Mac OS X 13_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.5 Safari/605.1.15',
      'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36'
  ]
  import random
  header = {'User-Agent': random.choice(ua_list)}
  

内容的提问来源于stack exchange，提问作者Арсений Усков