org.springframework.web.reactive.HandlerAdapter Maven / Gradle / Ivy
/*
* Copyright 2002-2022 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.reactive;
import reactor.core.publisher.Mono;
import org.springframework.web.server.ServerWebExchange;
/**
* Contract to abstract the details of invoking a handler of a given type.
*
* An implementation can also choose to be an instance of
* {@link DispatchExceptionHandler} if it wants to handle exceptions that occur
* before the request is successfully mapped to a handler. This allows a
* {@code HandlerAdapter} to expose the same exception handling both for handler
* invocation errors and for errors before a handler is selected.
* In Reactive Streams terms, {@link #handle} handles the onNext signal, while
* {@link DispatchExceptionHandler#handleError} handles the onError signal
* from the dispatch processing chain.
*
* @author Rossen Stoyanchev
* @author Sebastien Deleuze
* @since 5.0
*/
public interface HandlerAdapter {
/**
* Whether this {@code HandlerAdapter} supports the given {@code handler}.
* @param handler the handler object to check
* @return whether the handler is supported
*/
boolean supports(Object handler);
/**
* Handle the request with the given handler, previously checked via
* {@link #supports(Object)}.
*
Implementations should consider the following for exception handling:
*
* - Handle invocation exceptions within this method.
*
- {@link HandlerResult#setExceptionHandler(DispatchExceptionHandler)
* Set an exception handler} on the returned {@code HandlerResult} to handle
* deferred exceptions from asynchronous return values, and to handle
* exceptions from response rendering.
*
- Implement {@link DispatchExceptionHandler} to extend exception
* handling to exceptions that occur before a handler is selected.
*
* @param exchange current server exchange
* @param handler the selected handler which must have been previously
* checked via {@link #supports(Object)}
* @return {@link Mono} that emits a {@code HandlerResult}, or completes
* empty if the request is fully handled; any error signal would not be
* handled within the {@link DispatcherHandler}, and would instead be
* processed by the chain of registered
* {@link org.springframework.web.server.WebExceptionHandler}s at the end
* of the {@link org.springframework.web.server.WebFilter} chain
*/
Mono handle(ServerWebExchange exchange, Object handler);
}