Package dev.relism.flash.routing

Interface Middleware

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface Middleware
Stateless interceptor applied around a RequestHandler.

Middleware is composed once at registration time and stored as a pre-built handler chain inside the router's state machine. There is zero runtime overhead: no lists are visited, no lookups performed, and no objects allocated on the request hot-path.

Middleware is intentionally stateless — it can read Request, write to Response, and decide whether to call next or short-circuit. Shared state between layers belongs in HDI handler chains, not here. 


 // Inline definition — pure lambda, no wrapper types needed
 Middleware auth = next -> (req, res) -> {
     if (req.header("Authorization") == null) { res.status(401); return null; }
     return next.handle(req, res);
 };

 // Named reusable chain — composed into a single object at call time
 Middleware secured = Middleware.of(cors, auth, rateLimit);

 // Router-level: applied to every handler registered on this router
 AbstractRouter api = new MyRouter(cors, auth);

 // Handler-level: applied only to this route
 app.get("/admin", (req, res) -> "secret", auth);
 app.get("/log",   handler, logging, auth);

  • Method Details

    • wrap

      SimpleHandler.FunctionalHandler wrap(RequestHandler next)
      Wraps next with this middleware's logic. Called once at boot time during handler registration. Returns a SimpleHandler.FunctionalHandler lambda — no wrapper types required at the call site.

      The returned functional handler is boxed into a SimpleHandler internally by AbstractRouter; callers never need to do this manually.

    • of

      static Middleware of(Middleware... chain)
      Composes an ordered chain of middlewares into a single Middleware. The first element is the outermost wrapper and therefore executes first.

      The composition loop runs once when wrap(dev.relism.flash.models.RequestHandler) is called (i.e. at registration time), not at construction of the chain. Zero allocations on the hot-path. 

      
 Middleware secured = Middleware.of(cors, auth, rateLimit);
 // execution order: cors → auth → rateLimit → handler