How Spring MVC Routes HTTP Requests: DispatcherServlet, Mappings, and Adapters Explained
Spring MVC's DispatcherServlet acts as a central gateway that processes every incoming HTTP request without containing any application logic itself. It delegates three key questions to separate objects: a HandlerMapping identifies which controller method should handle the request, a HandlerAdapter determines how to invoke that method, and argument resolvers convert raw request data into typed Java parameters. The DispatcherServlet maintains an ordered list of handler mappings, querying each in sequence and using the first match, which means broadly mapped controllers can unintentionally shadow static resources. When no full route match is found, Spring checks partial matches to return meaningful error codes such as 404 for missing routes, 405 for wrong HTTP methods, 415 for unsupported content types, and 406 for unacceptable response formats. Routes can also be registered or removed at runtime via Spring's registerMapping() and unregisterMapping() APIs, though most applications rely on startup-time discovery.
