遇到问题：qt.qpa.xcb: could not connect to display
解决办法，在命令行输入：
export DISPLAY=:0然后重新跑python程序，解决！
参考博客：qt.qpa.xcb: could not connect to displayqt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.This application failed to start because no Qt platform plugin could be initialized. Reinstalling -高性能服务器开发
