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网站后台管理系统怎么弄,dede 手机网站,郑州哪个妇科医院检查比较好,上海十大网站排名Python 第二阶段 - 爬虫入门 🎯 今日目标掌握网页分页的原理和定位“下一页”的链接能编写循环逻辑自动翻页抓取内容将多页抓取整合到爬虫系统中 📘 学习内容详解 🔁 网页分页逻辑介绍以 quotes.toscrape.com 为例： 首页链…

Python 第二阶段 - 爬虫入门

🎯 今日目标

掌握网页分页的原理和定位“下一页”的链接
能编写循环逻辑自动翻页抓取内容
将多页抓取整合到爬虫系统中

📘 学习内容详解

🔁 网页分页逻辑介绍
以 quotes.toscrape.com 为例：

首页链接：https://quotes.toscrape.com/
下一页链接：<li class="next"><a href="/page/2/">Next</a></li>

我们可以通过 BeautifulSoup 查找li.next > a['href'] 获取下一页地址，并拼接 URL。

🧪 核心思路伪代码

while True:1. 请求当前页 URL2. 解析 HTML，提取所需内容3. 判断是否存在下一页链接- 如果有，拼接新 URL，继续循环- 如果没有，break 退出循环

💻 示例代码（多页抓取）

import requests
from bs4 import BeautifulSoup
from urllib.parse import urljoindef scrape_all_quotes(start_url):quotes = []url = start_urlwhile url:print(f"正在抓取：{url}")res = requests.get(url)soup = BeautifulSoup(res.text, 'lxml')for quote_block in soup.find_all("div", class_="quote"):quote_text = quote_block.find("span", class_="text").text.strip()author = quote_block.find("small", class_="author").text.strip()tags = [tag.text for tag in quote_block.find_all("a", class_="tag")]quotes.append({"quote": quote_text,"author": author,"tags": tags})# 查找下一页next_link = soup.select_one("li.next > a")if next_link:next_href = next_link['href']url = urljoin(url, next_href)  # 拼接为完整URLelse:url = Nonereturn quotesif __name__ == "__main__":all_quotes = scrape_all_quotes("https://quotes.toscrape.com/")print(f"共抓取到 {len(all_quotes)} 条名言")# 示例输出前3条for quote in all_quotes[:3]:print(f"\n{quote['quote']}\n—— {quote['author']}｜标签：{', '.join(quote['tags'])}")

🧠 今日练习任务

修改已有爬虫，实现抓取所有页面的名言数据
使用 len() 查看共抓取多少条数据

额外挑战：将所有数据保存为 JSON 文件（使用 json.dump）

练习代码：

import requests
from bs4 import BeautifulSoup
from urllib.parse import urljoin
import jsondef scrape_all_quotes(start_url):quotes = []url = start_urlwhile url:print(f"抓取页面：{url}")response = requests.get(url)soup = BeautifulSoup(response.text, "lxml")quote_blocks = soup.find_all("div", class_="quote")for block in quote_blocks:text = block.find("span", class_="text").text.strip()author = block.find("small", class_="author").text.strip()tags = [tag.text for tag in block.find_all("a", class_="tag")]quotes.append({"quote": text,"author": author,"tags": tags})# 找到下一页链接next_link = soup.select_one("li.next > a")if next_link:next_href = next_link['href']url = urljoin(url, next_href)else:url = Nonereturn quotesif __name__ == "__main__":start_url = "https://quotes.toscrape.com/"all_quotes = scrape_all_quotes(start_url)print(f"\n共抓取到 {len(all_quotes)} 条名言。\n")# 保存到 JSON 文件output_file = "quotes.json"with open(output_file, "w", encoding="utf-8") as f:json.dump(all_quotes, f, ensure_ascii=False, indent=2)print(f"数据已保存到文件：{output_file}")

运行输出：

正在抓取：https://quotes.toscrape.com/
正在抓取：https://quotes.toscrape.com/page/2/
正在抓取：https://quotes.toscrape.com/page/3/
正在抓取：https://quotes.toscrape.com/page/4/
正在抓取：https://quotes.toscrape.com/page/5/
正在抓取：https://quotes.toscrape.com/page/6/
正在抓取：https://quotes.toscrape.com/page/7/
正在抓取：https://quotes.toscrape.com/page/8/
正在抓取：https://quotes.toscrape.com/page/9/
正在抓取：https://quotes.toscrape.com/page/10/
共抓取到 100 条名言
数据已保存到文件：quotes.json

quotes.json文件输出：

[{"quote": "“The world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.”","author": "Albert Einstein","tags": ["change","deep-thoughts","thinking","world"]},{"quote": "“It is our choices, Harry, that show what we truly are, far more than our abilities.”","author": "J.K. Rowling","tags": ["abilities","choices"]},{"quote": "“There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.”","author": "Albert Einstein","tags": ["inspirational","life","live","miracle","miracles"]},... # 此处省去95条数据{"quote": "“A person's a person, no matter how small.”","author": "Dr. Seuss","tags": ["inspirational"]},{"quote": "“... a mind needs books as a sword needs a whetstone, if it is to keep its edge.”","author": "George R.R. Martin","tags": ["books","mind"]}