SpringMVC     =====>      Spring WebFlux

DispatchServlet =====> DispatchHandler

路由匹配： 
HandlerMapping =====>HandlerMapping 

Controller/Servlet/ @RequetMapping

HanderAdaper  ====>   HanderAdaper

Hander              =====>  WebHander


http://localhost:8021/order/findOrderByUserId/1
===>>>
http://localhost:8888/mall-order/order/findOrderByUserId/1

mall-order---> localhost:8021

====>
http://localhost:8888/order/findOrderByUserId/1

localhost:8888====> localhost:8021
/order/       mall-order

lb://mall-order      8020,8021      8021
http://localhost:8021/order/findOrderByUserId/1
 
gateway  route&predicates  建立映射关系