错误描述

cmd输出的异常信息

Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple/
Collecting selenium

  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x000002BFE5592EF0>: Failed to establish a new connection: [Errno 11001] getaddrinfo failed')': /simple/selenium/
  Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x000002BFE5592940>: Failed to establish a new connection: [Errno 11001] getaddrinfo failed')': /simple/selenium/
  Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x000002BFE55928D0>: Failed to establish a new connection: [Errno 11001] getaddrinfo failed')': /simple/selenium/
  Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x000002BFE5592AC8>: Failed to establish a new connection: [Errno 11001] getaddrinfo failed')': /simple/selenium/
  Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x000002BFE5737BA8>: Failed to establish a new connection: [Errno 11001] getaddrinfo failed')': /simple/selenium/
  Could not find a version that satisfies the requirement selenium (from versions: )
No matching distribution found for selenium

pycharm安装库失败
在这里插入图片描述

错因分析

由于GFW的存在，当我们在使用pip下载安装某个库的时候，会遇到莫名其妙的网络问题，比如我初学就死活安装不上selenium库。

解决办法

临时修改

在使用pip的时候加参数-i，如下：
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple 库名

永久修改

Linux下，修改~/.pip/pip.conf(或者创建一个),将index-url变量修改为所要更换的源地址:

[global]
index-url = https://pypi.tuna.tsinghua.edu.cn/simple

windows下
1.在user目录中创建一个pip目录,如C:\Users\xx\pip
在这里插入图片描述
2.新建文件pip.ini

写入如下内容：

[global]

timeout = 6000

index-url = https://pypi.tuna.tsinghua.edu.cn/simple/

trusted-host = mirrors.tsinghua.com

我在这用的是清华的镜像，附上一些其他好用的供大家选择

国内镜像


阿里云	http://mirrors.aliyun.com/pypi/simple/
中国科技大学	https://pypi.mirrors.ustc.edu.cn/simple/
豆瓣	http://pypi.douban.com/simple
中国科学院	http://pypi.mirrors.opencas.cn/simple/
清华大学	https://pypi.tuna.tsinghua.edu.cn/simple/

python安装库超时，修改pip源