IDEA Error:java: 无效的源发行版: 11错误

https://blog.csdn.net/qq_41153943/article/details/107610454

javax.servlet.ServletException: Servlet execution threw an exception org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

https://www.cnblogs.com/gui0/p/15630063.html