Python3.3以上的版本通过venv模块原生支持虚拟环境，可以代替Python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。Python3.3中使用”venv”命令创建的环境不包含”pip”，你需要进行手动安装。在Python3.4中改进了这一个缺陷。

   一、在当前目录创建虚拟环境：

    $ python -m venv .

    二、”venv”的详细使用参数:

    usage: venv [-h] [–system-site-packages] [–symlinks] [–clear]

                [–upgrade] [–without-pip] ENV_DIR [ENV_DIR …]

    Creates virtual Python environments in one or more target directories.

    positional arguments:

    ENV_DIR             A directory to create the environment in.

    optional arguments:

    -h, –help　　　　show this help message and exit

    –system-site-packages　　　　Give access to the global site-packages dir to the  virtual environment.

    –symlinks　　　　Try to use symlinks rather than copies, when symlinks are not the default for the platform.

    –copies　　　　Try to use copies rather than symlinks, even when symlinks are the default for the platform.

    –clear　　　　Delete the environment directory if it already exists. If not specified and the directory exists, an error is raised.

    –upgrade　　　　Upgrade the environment directory to use this version of Python, assuming Python has been upgraded in-place.

    –without-pip　　　　Skips installing or upgrading pip in the virtual environment (pip is bootstrapped by default)

　　三、激活虚拟环境

　　Posix标准平台下：$ source <venv>/bin/activate

　　Windows cmd ：　C:> <venv>/Scripts/activate.bat

　　Windows PowerShell：　PS C:> <venv>/Scripts/Activate.ps1