(Quickly understand the principle of netty. Netty, like Nodejs, is an open source, non blocking, large concurrent, multithreaded open source structure. It can quickly implement and provide the service end program for mobile APP docking. Netty is developed based on JAVA, with clear structure and quick operation. The project I uploaded uses Netty to implement websocket and simple webserver, and on this basis, miscellaneous functions can be realized.)