001/* 002 * Copyright 2002-2017 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 strategy for resolving a request to a server-side resource. 028 * 029 * <p>Provides mechanisms for resolving an incoming request to an actual 030 * {@link org.springframework.core.io.Resource} and for obtaining the 031 * public URL path that clients should use when requesting the resource. 032 * 033 * @author Jeremy Grelle 034 * @author Rossen Stoyanchev 035 * @author Sam Brannen 036 * @since 4.1 037 * @see org.springframework.web.servlet.resource.ResourceResolverChain 038 */ 039public interface ResourceResolver { 040 041 /** 042 * Resolve the supplied request and request path to a {@link Resource} that 043 * exists under one of the given resource locations. 044 * @param request the current request (may not be present in some calls) 045 * @param requestPath the portion of the request path to use 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 {@code null} if unresolved 049 */ 050 @Nullable 051 Resource resolveResource(@Nullable HttpServletRequest request, String requestPath, 052 List<? extends Resource> locations, ResourceResolverChain chain); 053 054 /** 055 * Resolve the externally facing <em>public</em> URL path for clients to use 056 * to access the resource that is located at the given <em>internal</em> 057 * resource path. 058 * <p>This is useful when rendering URL links to clients. 059 * @param resourcePath the internal resource 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 {@code null} if unresolved 063 */ 064 @Nullable 065 String resolveUrlPath(String resourcePath, List<? extends Resource> locations, ResourceResolverChain chain); 066 067}