我的第1个爬虫程序——豆瓣Top250爬虫的详细步骤指南

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一、创建隔离开发环境

1. 使用虚拟环境（推荐`venv`）

# 在项目目录打开终端执行
python -m venv douban_env      # 创建虚拟环境
source douban_env/bin/activate # Linux/macOS激活
douban_env\Scripts\activate   # Windows激活

2. 安装依赖库

pip install requests beautifulsoup4 lxml

3. 生成依赖清单

pip freeze > requirements.txt

二、项目架构设计

douban_top250/
├── config/               # 配置文件
│   └── settings.py
├── core/                 # 核心逻辑
│   ├── spider.py
│   └── storage.py
├── utils/                # 工具函数
│   └── helper.py
├── output/               # 输出目录
├── main.py               # 主入口
└── requirements.txt      # 依赖清单

三、分步实现

步骤1：创建配置文件 `config/settings.py`

# 请求配置
HEADERS = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36','Referer': 'https://movie.douban.com/'
}# 目标URL配置
BASE_URL = 'https://movie.douban.com/top250'# 存储配置
OUTPUT_DIR = './output'
CSV_HEADERS = ['标题', '评分', '年份', '国家', '类型', '链接']# 容错配置
SAFE_MODE = True  # 遇到错误时跳过条目而不是终止
UNKNOWN_PLACEHOLDER = "未知"  # 数据缺失时的占位符

步骤2：编写工具类 `utils/helper.py`

import random
import timedef random_delay(min=1, max=3):"""随机延迟防止被封"""time.sleep(random.uniform(min, max))def make_soup(html):"""创建BeautifulSoup对象"""from bs4 import BeautifulSoupreturn BeautifulSoup(html, 'lxml')

步骤3：核心爬虫逻辑 `core/spider.py`

import requests
from config import settings
from utils.helper import random_delay, make_soupclass DoubanSpider:def __init__(self):self.session = requests.Session()self.session.headers.update(settings.HEADERS)def fetch_page(self, url):"""获取页面内容"""try:random_delay()response = self.session.get(url)response.raise_for_status()  # 自动处理HTTP错误return response.textexcept requests.RequestException as e:print(f"请求失败: {str(e)}")return Nonedef parse_page(self, html):"""改进后的解析方法"""soup = make_soup(html)movies = []for item in soup.find_all('div', class_='item'):try:# 标题与链接title = item.find('span', class_='title').text.strip()rating = item.find('span', class_='rating_num').text.strip()link = item.find('a')['href']# 详细信息解析（稳健版）info_div = item.find('div', class_='bd')info_text = info_div.p.get_text(" ", strip=True)  # 用空格替代换行# 使用正则表达式提取年份/国家/类型import repattern = r'(\d{4})[^/]*(.*?)\s+/\s+(.*?)$'match = re.search(pattern, info_text)if match:year = match.group(1).strip()country = match.group(2).strip().replace('/', ' ')  # 处理国家中的斜杠genre = match.group(3).strip()else:year = country = genre = "N/A"  # 无法解析时填充默认值movies.append({'标题': title,'评分': rating,'年份': year,'国家': country,'类型': genre,'链接': link})except Exception as e:print(f"解析条目失败: {str(e)}")continue  # 跳过当前条目return moviesdef get_all_pages(self):"""处理分页"""all_movies = []start = 0while True:url = f"{settings.BASE_URL}?start={start}"html = self.fetch_page(url)if not html:breakmovies = self.parse_page(html)if not movies:breakall_movies.extend(movies)start += 25# 检查是否还有下一页if start >= 250:  # Top250最多250条breakreturn all_movies

步骤4：数据存储模块 `core/storage.py`

import csv
import json
import os
from config import settingsclass DataStorage:@staticmethoddef save_csv(data, filename='douban_top250.csv'):os.makedirs(settings.OUTPUT_DIR, exist_ok=True)path = os.path.join(settings.OUTPUT_DIR, filename)with open(path, 'w', newline='', encoding='utf-8') as f:writer = csv.DictWriter(f, fieldnames=settings.CSV_HEADERS)writer.writeheader()writer.writerows(data)print(f"数据已保存至 {path}")@staticmethoddef save_json(data, filename='douban_top250.json'):os.makedirs(settings.OUTPUT_DIR, exist_ok=True)path = os.path.join(settings.OUTPUT_DIR, filename)with open(path, 'w', encoding='utf-8') as f:json.dump(data, f, ensure_ascii=False, indent=2)print(f"数据已保存至 {path}")

步骤5：主程序 `main.py`

from core.spider import DoubanSpider
from core.storage import DataStoragedef main():# 检查robots协议print("豆瓣 robots.txt 重要条款：")print("User-agent: *")print("Disallow: /search")  # 实际需查看最新内容# 执行爬虫spider = DoubanSpider()movies_data = spider.get_all_pages()# 存储数据if movies_data:DataStorage.save_csv(movies_data)DataStorage.save_json(movies_data)else:print("未获取到有效数据")if __name__ == '__main__':main()

四、运行与验证

在激活的虚拟环境中执行：

python main.py

检查 output/ 目录生成的 CSV 和 JSON 文件

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五、高级优化建议

异常处理增强：

# 在spider类中添加重试机制
def fetch_page(self, url, retries=3):for attempt in range(retries):try:# ...原有代码...except requests.RequestException as e:if attempt == retries - 1:raiseprint(f"重试中 ({attempt+1}/{retries})...")time.sleep(2 ** attempt)  # 指数退避

请求头轮换：

# 在settings.py中添加多个User-Agent
USER_AGENTS = ['Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36','Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15','Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36'
]# 在helper.py中添加选择函数
def get_random_user_agent():return random.choice(settings.USER_AGENTS)

代理设置（如果需要）：

# 在spider初始化时添加
def __init__(self, proxy=None):if proxy:self.session.proxies = {'http': proxy, 'https': proxy}

六、法律合规检查

访问 https://www.douban.com/robots.txt 查看协议
重点条款：

User-agent: *
Disallow: /subject_search
Disallow: /amazon_search
Disallow: /search
Disallow: /group/search
Disallow: /event/search
Disallow: /forum/search
Disallow: /game/search