python 爬虫 网络超时与异常_httpconnectionpool(host='114.115.236.206', port=99

在访问一个网页时，如果该网页长时间未响应，系统就会判断该网页超时，无法打开网页。模拟代码如下：

import requests
for a in range(0,100):
    try:
        response = requests.get('http://www.baidu.com/', timeout=0.02)
        print(response.status_code)
    except Exception as e:
        print('异常'+str(e))

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抛出的异常：

异常HTTPConnectionPool(host='www.baidu.com', port=80): Read timed out. (read timeout=0.02)
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识别网络异常的分类
针对网络异常信息，requests模块同样提供了三种常见的网络异常捕获异常，代码如下：

import requests
from requests.exceptions import ReadTimeout,HTTPError,RequestException
for a in range(0,100):
    try:
        response = requests.get('http://www.baidu.com/', timeout=0.02)
        print(response.status_code)
    except ReadTimeout:#超时异常
        print('time out')
    except HTTPError:#HTTP异常
        print('httperror')
    except RequestException:#请求异常
        print('reqerror')
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