001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.reactive.resource;
018
019import java.util.List;
020
021import reactor.core.publisher.Mono;
022
023import org.springframework.core.io.Resource;
024import org.springframework.http.server.RequestPath;
025import org.springframework.lang.Nullable;
026import org.springframework.web.server.ServerWebExchange;
027
028/**
029 * A strategy for resolving a request to a server-side resource.
030 *
031 * <p>Provides mechanisms for resolving an incoming request to an actual
032 * {@link Resource} and for obtaining the
033 * public URL path that clients should use when requesting the resource.
034 *
035 * @author Rossen Stoyanchev
036 * @since 5.0
037 */
038public interface ResourceResolver {
039
040        /**
041         * Resolve the supplied request and request path to a {@link Resource} that
042         * exists under one of the given resource locations.
043         * @param exchange the current exchange
044         * @param requestPath the portion of the request path to use. This is
045         * expected to be the encoded path, i.e. {@link RequestPath#value()}.
046         * @param locations the locations to search in when looking up resources
047         * @param chain the chain of remaining resolvers to delegate to
048         * @return the resolved resource or an empty {@code Mono} if unresolved
049         */
050        Mono<Resource> resolveResource(@Nullable ServerWebExchange exchange, String requestPath,
051                        List<? extends Resource> locations, ResourceResolverChain chain);
052
053        /**
054         * Resolve the externally facing <em>public</em> URL path for clients to use
055         * to access the resource that is located at the given <em>internal</em>
056         * resource path.
057         * <p>This is useful when rendering URL links to clients.
058         * @param resourcePath the "internal" resource path to resolve a path for
059         * public use. This is expected to be the encoded path.
060         * @param locations the locations to search in when looking up resources
061         * @param chain the chain of resolvers to delegate to
062         * @return the resolved public URL path or an empty {@code Mono} if unresolved
063         */
064        Mono<String> resolveUrlPath(String resourcePath, List<? extends Resource> locations,
065                        ResourceResolverChain chain);
066
067}