001/* 002 * Copyright 2002-2018 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; 020 021import javax.servlet.http.HttpServletRequest; 022 023import org.springframework.core.io.Resource; 024import org.springframework.lang.Nullable; 025 026/** 027 * A contract for invoking a chain of {@link ResourceResolver ResourceResolvers} where each resolver 028 * is given a reference to the chain allowing it to delegate when necessary. 029 * 030 * @author Jeremy Grelle 031 * @author Rossen Stoyanchev 032 * @author Sam Brannen 033 * @since 4.1 034 */ 035public interface ResourceResolverChain { 036 037 /** 038 * Resolve the supplied request and request path to a {@link Resource} that 039 * exists under one of the given resource locations. 040 * @param request the current request 041 * @param requestPath the portion of the request path to use 042 * @param locations the locations to search in when looking up resources 043 * @return the resolved resource, or {@code null} if unresolved 044 */ 045 @Nullable 046 Resource resolveResource( 047 @Nullable HttpServletRequest request, String requestPath, List<? extends Resource> locations); 048 049 /** 050 * Resolve the externally facing <em>public</em> URL path for clients to use 051 * to access the resource that is located at the given <em>internal</em> 052 * resource path. 053 * <p>This is useful when rendering URL links to clients. 054 * @param resourcePath the internal resource path 055 * @param locations the locations to search in when looking up resources 056 * @return the resolved public URL path, or {@code null} if unresolved 057 */ 058 @Nullable 059 String resolveUrlPath(String resourcePath, List<? extends Resource> locations); 060 061}