mac中pip安装包报错解决方法
遇到问题：
mac使用pip安装selenium时，报：
➜ ~ pip3 install selenium
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ConnectTimeoutError(<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x106fa7c10>, 'Connection to pypi.org timed out. (connect timeout=15)')': /simple/selenium/
/packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl
ERROR: Could not install packages due to an EnvironmentError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl (Caused by ConnectTimeoutError(<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x1070e8390>, 'Connection to files.pythonhosted.org timed out. (connect timeout=15)'))
解决方法：
直接使用pip安装是会网络连接超时，要使用vpn，这里用了国内镜像pip源：
豆瓣(douban) http://pypi.douban.com/simple/
➜ ~ pip3 install selenium -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
Looking in indexes: http://pypi.douban.com/simple
Collecting selenium
Downloading http://pypi.doubanio.com/packages/80/d6/4294f0b4bce4de0abf13e17190289f9d0613b0a44e5dd6a7f5ca98459853/selenium-3.141.0-py2.py3-none-any.whl (904 kB)
|████████████████████████████████| 904 kB 6.2 MB/s
Collecting urllib3
Downloading http://pypi.doubanio.com/packages/e1/e5/df302e8017440f111c11cc41a6b432838672f5a70aa29227bf58149dc72f/urllib3-1.25.9-py2.py3-none-any.whl (126 kB)
|████████████████████████████████| 126 kB 5.7 MB/s
Installing collected packages: urllib3, selenium
Successfully installed selenium-3.141.0 urllib3-1.25.9