使用Chocolatey Windows软件包管理器安装/升级Python
假设您有Python 2.7.16：
C:\Windows\system32>python --version
python2 2.7.16
...并且您想升级到（现在）3.xy版本。有一种简单的方法可以使用Windows软件包管理工具来并行安装Python3.xy。
现在，现代Windows具有包管理功能，就像Debian Linux发行版具有apt-get一样，而RedHat具有dnf：我们可以为我们使用它了！叫做 Chocolatey。
什么是巧克力味？
Chocolatey是一个可脚本化的命令行工具，基于.NET 4.0和nuget程序包管理器引入了Visual Studio。
如果您想了解Chocolatey以及为什么要使用它，某些在这里阅读本文的人可能会发现它特别有用，请访问https://chocolatey.org/docs/why
安装Chocolatey
要获取Chocolatey Package Manager，请按照https://chocolatey.org/docs/installation#installing-chocolatey所述的过程进行操作，
我将在这里为您总结。基本上有两个选项：使用cmd提示符或使用PowerShell提示符。
CMD提示巧克力般的安装
启动管理命令提示符。在Windows 10上，执行以下操作：
- Windows+R
- 输入cmd
- 按ctrl+ shift+Enter
如果您没有系统管理员权限，请访问Chocolatey网站。您可能并不完全走运，可以执行有限的本地安装，但在此不做介绍。
- 将以下字符串复制到命令提示符中，然后输入Enter：
@"%SystemRoot%\System32\WindowsPowerShell\v1.0\powershell.exe" -NoProfile -InputFormat None -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
Chocolatey将为您下载和安装，如下所示：
Getting latest version of the Chocolatey package for download.
Getting Chocolatey from https://chocolatey.org/api/v2/package/chocolatey/0.10.11.
Downloading 7-Zip commandline tool prior to extraction.
Extracting C:\Users\blahblahblah\AppData\Local\Temp\chocolatey\chocInstall\chocolatey.zip to C:\Users\blahblahblah\AppData\Local\Temp\chocolatey\chocInstall...
Installing chocolatey on this machine
Creating ChocolateyInstall as an environment variable (targeting 'Machine')
Setting ChocolateyInstall to 'C:\ProgramData\chocolatey'
WARNING: It's very likely you will need to close and reopen your shell
before you can use choco.
Restricting write permissions to Administrators
We are setting up the Chocolatey package repository.
The packages themselves go to 'C:\ProgramData\chocolatey\lib'
(i.e. C:\ProgramData\chocolatey\lib\yourPackageName).
A shim file for the command line goes to 'C:\ProgramData\chocolatey\bin'
and points to an executable in 'C:\ProgramData\chocolatey\lib\yourPackageName'.
Creating Chocolatey folders if they do not already exist.
WARNING: You can safely ignore errors related to missing log files when
upgrading from a version of Chocolatey less than 0.9.9.
'Batch file could not be found' is also safe to ignore.
'The system cannot find the file specified' - also safe.
chocolatey.nupkg file not installed in lib.
Attempting to locate it from bootstrapper.
PATH environment variable does not have C:\ProgramData\chocolatey\bin in it. Adding...
WARNING: Not setting tab completion: Profile file does not exist at 'C:\Users\blahblahblah\Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1'.
Chocolatey (choco.exe) is now ready.
You can call choco from anywhere, command line or powershell by typing choco.
Run choco /? for a list of functions.
You may need to shut down and restart powershell and/or consoles
first prior to using choco.
Ensuring chocolatey commands are on the path
Ensuring chocolatey.nupkg is in the lib folder
要么退出的CMD提示或键入以下命令以重新加载环境变量：
refreshenv
PowerShell Chocolatey安装
如果您更喜欢PowerShell而不是cmd提示符，则可以从那里直接执行此操作，但是必须告诉PowerShell使用正确的脚本执行策略运行才能使其正常工作。在Windows 10上，我发现最简单的方法是在Windows按钮旁边的Cortana搜索栏中键入以下内容：
PowerShell.exe
接下来，右键单击弹出菜单中的“最佳匹配”选项，然后选择“以管理员身份运行”
现在您已经在PowerShell中，希望以管理员权限运行，执行以下命令以安装Chocolatey：
Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))
PowerShell将为您下载Chocolatey并启动安装。只需要一点时间。它看起来与CMD安装完全一样，可能会保存一些精美的彩色文本。
无论是退出的PowerShell或键入以下命令来重新加载环境变量：
refreshenv
升级Python
无论您使用PowerShell还是cmd提示符，choco命令都是相同的。按照上述说明启动您喜欢的游戏。我将使用管理员cmd提示符：
C:\WINDOWS\system32>choco upgrade python -y
本质上，Chocolatey会告诉您“嘿，未安装Python”，因为您来自2.7.x，它将2.7版本视为完全独立。它只会为您提供最新版本3.xy（在撰写本文时为3.7.2，但几个月后会更改）：
Chocolatey v0.10.11
Upgrading the following packages:
python
By upgrading you accept licenses for the packages.
python is not installed. Installing...
python3 v3.x.y [Approved]
python3 package files upgrade completed. Performing other installation steps.
Installing 64-bit python3...
python3 has been installed.
Installed to: 'C:\Python37'
python3 can be automatically uninstalled.
Environment Vars (like PATH) have changed. Close/reopen your shell to
see the changes (or in powershell/cmd.exe just type `refreshenv`).
The upgrade of python3 was successful.
Software installed as 'exe', install location is likely default.
python v3.x.y [Approved]
python package files upgrade completed. Performing other installation steps.
The upgrade of python was successful.
Software install location not explicitly set, could be in package or
default install location if installer.
Chocolatey upgraded 2/2 packages.
See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).
要么退出CMD的出/ Powershell的提示和重新输入，或者使用然后键入refreshenv PY --version
C:\Windows\System32>refreshenv
Refreshing environment variables from registry for cmd.exe. Please wait...Finished..
C:\Windows\system32>py --version
Python 3.7.2
请注意，当您在命令行中键入Python时，最新的Python安装现在将接管。您可以使用以下命令来运行任一版本：
py -2
Python 2.7.16 (v2.7.16:413a49145e, Mar 4 2019, 01:37:19) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
C:\>py -3
Python 3.7.2 (tags/v3.7.2:9a3ffc0492, Dec 23 2018, 23:09:28) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>exit()
C:\>
从这里，我建议您使用Python pip实用程序安装所需的任何软件包。例如，假设您要安装Flask。下面的命令首先升级pip，然后安装Flask
C:\>py -3 -m pip install --upgrade pip
Collecting pip
Downloading https://files.pythonhosted.org/packages/d8/f3/413bab4ff08e1fc4828dfc59996d721917df8e8583ea85385d51125dceff/pip-19.0.3-py2.py3-none-any.whl (1.4MB)
100% |████████████████████████████████| 1.4MB 1.6MB/s
Installing collected packages: pip
Found existing installation: pip 18.1
Uninstalling pip-18.1:
Successfully uninstalled pip-18.1
Successfully installed pip-19.0.3
c:\>py -3 -m pip install Flask
...会成功的 快乐的Pythoning！
