【Windows】anaconda虚拟环境中安装包显示编码错误

使用cmd命令窗在conda的虚拟环境中使用pip或者conda命令安装包时，显示如下错误：

    ERROR: Command errored out with exit status 3221226505:
     command: 'C:\SoftWare\Anaconda\envs\pytorch\python.exe' -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\CRUISE~1\\AppData\\Local\\Temp\\pip-req-build-6wd_bvgm\\setup.py'"'"'; __file__='"'"'C:\\Users\\CRUISE~1\\AppData\\Local\\Temp\\pip-req-build-6wd_bvgm\\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base 'C:\Users\CRUISE~1\AppData\Local\Temp\pip-req-build-6wd_bvgm\pip-egg-info'
         cwd: C:\Users\CRUISE~1\AppData\Local\Temp\pip-req-build-6wd_bvgm\
    Complete output (4 lines):
    Fatal Python error: init_sys_streams: can't initialize sys standard streams
    LookupError: unknown encoding: 65001

    Current thread 0x00002cec (most recent call first):
    ----------------------------------------
ERROR: Command errored out with exit status 3221226505: python setup.py egg_info Check the logs for full command output.

由错误可以看出是编码引起的，但是按照网上的方法使用chcp 936(简中)或者65001(UTF-8)都不行，原因应该是python不将65001识别为utf-8，之后使用以下命令解决：

set PYTHONIOENCODING=utf-8