Python爬虫四大神器全解析

Python爬虫四大核心工具解析

Python爬虫技术在现代数据采集和分析中扮演着重要角色。四大核心工具包括Requests、BeautifulSoup、Scrapy和Selenium，各自适用于不同场景。

Requests：HTTP请求库

Requests是Python中最常用的HTTP库，简化了HTTP请求的发送过程。支持GET、POST等多种请求方式，能够处理Cookies、Session和代理。

import requests
response = requests.get('https://example.com')
print(response.text)

Requests的优势在于简洁的API设计和高效的性能，适合快速抓取静态页面内容。但缺乏对JavaScript渲染的支持。

BeautifulSoup：HTML解析库

BeautifulSoup专注于HTML和XML文档的解析，支持多种解析器如lxml和html.parser。能快速定位和提取特定标签内容。

from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, 'lxml')
print(soup.find_all('a'))

BeautifulSoup适合处理结构化的HTML文档，常与Requests配合使用。但面对复杂页面时可能需要结合正则表达式。

Scrapy：爬虫框架

Scrapy是一个完整的爬虫框架，提供项目结构、中间件、管道等组件。支持分布式爬取和数据存储。

import scrapy
class MySpider(scrapy.Spider):
    name = 'example'
    start_urls = ['https://example.com']
    
    def parse(self, response):
        yield {'title': response.css('title::text').get()}

Scrapy适合大规模爬取项目，内置的Selector比BeautifulSoup性能更好。但学习曲线相对陡峭。

Selenium：浏览器自动化工具

Selenium通过控制真实浏览器解决JavaScript渲染问题。支持多种浏览器如Chrome和Firefox。

from selenium import webdriver
driver = webdriver.Chrome()
driver.get('https://example.com')
print(driver.page_source)

Selenium能模拟用户操作，适合动态加载的页面。但资源消耗较大，速度较慢。

工具对比与选型

静态页面抓取优先考虑Requests+BeautifulSoup组合；大规模项目选择Scrapy；需要处理JavaScript时使用Selenium。实际开发中常需要组合使用这些工具。

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