001/*
002 * Copyright 2002-2015 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.servlet.resource;
018
019import java.util.List;
020import javax.servlet.http.HttpServletRequest;
021
022import org.springframework.core.io.Resource;
023
024/**
025 * A contract for invoking a chain of {@link ResourceResolver}s where each resolver
026 * is given a reference to the chain allowing it to delegate when necessary.
027 *
028 * @author Jeremy Grelle
029 * @author Rossen Stoyanchev
030 * @author Sam Brannen
031 * @since 4.1
032 */
033public interface ResourceResolverChain {
034
035        /**
036         * Resolve the supplied request and request path to a {@link Resource} that
037         * exists under one of the given resource locations.
038         * @param request the current request
039         * @param requestPath the portion of the request path to use
040         * @param locations the locations to search in when looking up resources
041         * @return the resolved resource or {@code null} if unresolved
042         */
043        Resource resolveResource(HttpServletRequest request, String requestPath, List<? extends Resource> locations);
044
045        /**
046         * Resolve the externally facing <em>public</em> URL path for clients to use
047         * to access the resource that is located at the given <em>internal</em>
048         * resource path.
049         * <p>This is useful when rendering URL links to clients.
050         * @param resourcePath the internal resource path
051         * @param locations the locations to search in when looking up resources
052         * @return the resolved public URL path or {@code null} if unresolved
053         */
054        String resolveUrlPath(String resourcePath, List<? extends Resource> locations);
055
056}