刚开始反复报错，显示
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: off
Usage: flask run [OPTIONS]
Error: Could not locate a Flask application. You did not provide the "FLASK_APP" environment variable, and a "wsgi.py" or "app.
py" module was not found in the current directory.
最后找到问题，是终端问题
可以将终端换一下试试看
