python爬虫怎么爬取前几页

使用 Python 爬虫爬取前几页内容涉及以下步骤：1.导入请求和 BeautifulSoup 库；2.构造一个 HTTP 请求；3.解析响应为 HTML 文档；4.使用循环遍历前几页，提取内容并打印；5.构造下一页 URL 并发送 HTTP 请求；6.解析下一页 HTML 文档并更新 soup 变量；7.循环结束，爬取完成。

如何使用 Python 爬虫爬取前几页内容

步骤 1：导入必要的库

<code class="python">import requests
from bs4 import BeautifulSoup</code>

步骤 2：构造一个 HTTP 请求

<code class="python">url = "https://example.com"
response = requests.get(url)</code>

步骤 3：将响应解析为 HTML

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<code class="python">soup = BeautifulSoup(response.text, "html.parser")</code>

步骤 4：遍历前几页

<code class="python">page_num = 1
while page_num <= 5:  # 爬取前 5 页
    # 提取当前页面的内容
    content = soup.find_all("div", class_="content")
    # 打印提取到的内容
    print(f"第 {page_num} 页：")
    print(content)

    # 构造下一页的 URL
    next_page_url = f"{url}/page/{page_num + 1}"

    # 发送下一页的 HTTP 请求
    next_page_response = requests.get(next_page_url)

    # 解析下一页的 HTML
    soup = BeautifulSoup(next_page_response.text, "html.parser")
    
    page_num += 1</code>

示例代码：

<code class="python">import requests
from bs4 import BeautifulSoup

# 爬取百度首页前 5 页的内容
url = "https://www.baidu.com"

response = requests.get(url)
soup = BeautifulSoup(response.text, "html.parser")

page_num = 1
while page_num <= 5:
    content = soup.find_all("div", class_="result")
    print(f"第 {page_num} 页：")
    print(content)
    
    next_page_url = f"{url}/s?wd=&pn={page_num * 10}"
    next_page_response = requests.get(next_page_url)
    soup = BeautifulSoup(next_page_response.text, "html.parser")
    
    page_num += 1</code>