python spider爬虫如何进行异常处理

在进行Python爬虫开发时，异常处理是确保程序稳定运行的关键。以下是一些常见的异常处理方法：

1. 使用try-except块： 在可能抛出异常的代码块中使用try和except块来捕获和处理异常。

   import requests try: response = requests.get('http://example.com') response.raise_for_status() # 如果响应状态码不是200，会抛出HTTPError异常 except requests.exceptions.HTTPError as e: print(f"HTTP Error: {e}") except requests.exceptions.RequestException as e: print(f"Request Exception: {e}") except Exception as e: print(f"Unexpected Error: {e}") else: print("Request successful") # 处理成功的响应 

2. 使用logging模块： 使用logging模块记录异常信息，以便后续分析和调试。

   import logging import requests logging.basicConfig(filename='spider.log', level=logging.ERROR) try: response = requests.get('http://example.com') response.raise_for_status() except requests.exceptions.HTTPError as e: logging.error(f"HTTP Error: {e}") except requests.exceptions.RequestException as e: logging.error(f"Request Exception: {e}") except Exception as e: logging.error(f"Unexpected Error: {e}") else: print("Request successful") # 处理成功的响应 

3. 使用finally块： finally块中的代码无论是否发生异常都会执行，适合用于清理资源。

   import requests try: response = requests.get('http://example.com') response.raise_for_status() except requests.exceptions.HTTPError as e: print(f"HTTP Error: {e}") except requests.exceptions.RequestException as e: print(f"Request Exception: {e}") except Exception as e: print(f"Unexpected Error: {e}") else: print("Request successful") # 处理成功的响应 finally: print("Request completed") 

4. 使用asyncio和aiohttp进行异步爬虫： 在异步爬虫中，可以使用try-except块来捕获和处理异常。

   import aiohttp import asyncio async def fetch(session, url): try: async with session.get(url) as response: response.raise_for_status() return await response.text() except aiohttp.ClientError as e: print(f"Client Error: {e}") except Exception as e: print(f"Unexpected Error: {e}") async def main(): async with aiohttp.ClientSession() as session: html = await fetch(session, 'http://example.com') print(html) loop = asyncio.get_event_loop() loop.run_until_complete(main()) 

通过这些方法，可以有效地处理爬虫过程中可能出现的各种异常，确保程序的稳定性和可靠性。