Python3虚拟环境--venv
Python3.3以上的版本通过venv模块原生支持虚拟环境，可以代替之前的virtualenv。
该venv模块提供了创建轻量级“虚拟环境”，提供与系统Python的隔离支持。每一个虚拟环境都有其自己的Python二进制（允许有不同的Python版本创作环境），并且可以拥有自己独立的一套Python包。
注意：python3.3中使用”venv”命令创建的环境不包含”pip”，需进行手动安装。Python3.4中改进了这一缺陷。
创建虚拟环境
1 python -m venv myvenv
此命令会在当前目录下生成一个名为myvenv的目录，myenv也是创建的虚拟环境名。
激活环境：
/Scripts/activate.bat
退出环境：
/Scripts/deactivate.bat
附：
venv使用参数：
1 usage: venv [-h] [--system-site-packages] [--symlinks] [--clear] 2 [--upgrade] [--without-pip] ENV_DIR [ENV_DIR ...] 3 4 Creates virtual Python environments in one or more target directories. 5 6 positional arguments: 7 ENV_DIR A directory to create the environment in. 8 9 optional arguments: 10 -h, --help show this help message and exit 11 --system-site-packages Give access to the global site-packages dir to the 12 virtual environment. 13 --symlinks Try to use symlinks rather than copies, when symlinks 14 are not the default for the platform. 15 --copies Try to use copies rather than symlinks, even when 16 symlinks are the default for the platform. 17 --clear Delete the environment directory if it already exists. 18 If not specified and the directory exists, an error is 19 raised. 20 --upgrade Upgrade the environment directory to use this version 21 of Python, assuming Python has been upgraded in-place. 22 --without-pip Skips installing or upgrading pip in the virtual 23 environment (pip is bootstrapped by default)
