Python中常见的网络爬虫问题及解决方案
概述：
一、反爬虫策略
反爬虫是指网站为了保护自身利益，采取一系列措施限制爬虫对网站的访问。常见的反爬虫策略包括IP封禁、验证码、登录限制等。以下是一些解决方案：
使用代理IP 1
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import requests
def get_html(url):
proxy = {
'http': 'http://username:password@proxy_ip:proxy_port',
'https': 'https://username:password@proxy_ip:proxy_port'
}
headers = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36'
}
try:
response = requests.get(url, proxies=proxy, headers=headers)
if response.status_code == 200:
return response.text
else:
return None
except requests.exceptions.RequestException as e:
return None
url = 'http://example.com'
html = get_html(url)
使用随机User-Agent头 1
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import requests
import random
def get_html(url):
user_agents = [
'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36',
'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36',
'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36'
]
headers = {
'User-Agent': random.choice(user_agents)
}
try:
response = requests.get(url, headers=headers)
if response.status_code == 200:
return response.text
else:
return None
except requests.exceptions.RequestException as e:
return None
url = 'http://example.com'
html = get_html(url)
二、页面解析
在爬取数据时，我们常需要对页面进行解析，提取所需的信息。以下是一些常见的页面解析问题及相应的解决方案：
静态页面解析 1
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import requests
from bs4 import BeautifulSoup
def get_html(url):
headers = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36'
}
try:
response = requests.get(url, headers=headers)
if response.status_code == 200:
return response.text
else:
return None
except requests.exceptions.RequestException as e:
return None
def get_info(html):
soup = BeautifulSoup(html, 'html.parser')
title = soup.title.text
return title
url = 'http://example.com'
html = get_html(url)
info = get_info(html)
动态页面解析 1
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from selenium import webdriver
def get_html(url):
driver = webdriver.Chrome('path/to/chromedriver')
driver.get(url)
html = driver.page_source
return html
def get_info(html):
# 解析获取所需信息
pass
url = 'http://example.com'
html = get_html(url)
info = get_info(html)
以上是Python中常见的网络爬虫问题及解决方案的概述。在实际开发过程中，根据不同的场景，可能会遇到更多的问题。希望本文能为读者在网络爬虫开发中提供一些参考和帮助。
