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.cache.Cache; 023import org.springframework.cache.CacheManager; 024import org.springframework.core.io.Resource; 025import org.springframework.util.Assert; 026 027/** 028 * A {@link org.springframework.web.servlet.resource.ResourceResolver} that 029 * resolves resources from a {@link org.springframework.cache.Cache} or otherwise 030 * delegates to the resolver chain and saves the result in the cache. 031 * 032 * @author Rossen Stoyanchev 033 * @author Brian Clozel 034 * @since 4.1 035 */ 036public class CachingResourceResolver extends AbstractResourceResolver { 037 038 public static final String RESOLVED_RESOURCE_CACHE_KEY_PREFIX = "resolvedResource:"; 039 040 public static final String RESOLVED_URL_PATH_CACHE_KEY_PREFIX = "resolvedUrlPath:"; 041 042 043 private final Cache cache; 044 045 046 public CachingResourceResolver(CacheManager cacheManager, String cacheName) { 047 this(cacheManager.getCache(cacheName)); 048 } 049 050 public CachingResourceResolver(Cache cache) { 051 Assert.notNull(cache, "Cache is required"); 052 this.cache = cache; 053 } 054 055 056 /** 057 * Return the configured {@code Cache}. 058 */ 059 public Cache getCache() { 060 return this.cache; 061 } 062 063 064 @Override 065 protected Resource resolveResourceInternal(HttpServletRequest request, String requestPath, 066 List<? extends Resource> locations, ResourceResolverChain chain) { 067 068 String key = computeKey(request, requestPath); 069 Resource resource = this.cache.get(key, Resource.class); 070 071 if (resource != null) { 072 if (logger.isTraceEnabled()) { 073 logger.trace("Found match: " + resource); 074 } 075 return resource; 076 } 077 078 resource = chain.resolveResource(request, requestPath, locations); 079 if (resource != null) { 080 if (logger.isTraceEnabled()) { 081 logger.trace("Putting resolved resource in cache: " + resource); 082 } 083 this.cache.put(key, resource); 084 } 085 086 return resource; 087 } 088 089 protected String computeKey(HttpServletRequest request, String requestPath) { 090 StringBuilder key = new StringBuilder(RESOLVED_RESOURCE_CACHE_KEY_PREFIX); 091 key.append(requestPath); 092 if (request != null) { 093 String encoding = request.getHeader("Accept-Encoding"); 094 if (encoding != null && encoding.contains("gzip")) { 095 key.append("+encoding=gzip"); 096 } 097 } 098 return key.toString(); 099 } 100 101 @Override 102 protected String resolveUrlPathInternal(String resourceUrlPath, 103 List<? extends Resource> locations, ResourceResolverChain chain) { 104 105 String key = RESOLVED_URL_PATH_CACHE_KEY_PREFIX + resourceUrlPath; 106 String resolvedUrlPath = this.cache.get(key, String.class); 107 108 if (resolvedUrlPath != null) { 109 if (logger.isTraceEnabled()) { 110 logger.trace("Found match: \"" + resolvedUrlPath + "\""); 111 } 112 return resolvedUrlPath; 113 } 114 115 resolvedUrlPath = chain.resolveUrlPath(resourceUrlPath, locations); 116 if (resolvedUrlPath != null) { 117 if (logger.isTraceEnabled()) { 118 logger.trace("Putting resolved resource URL path in cache: \"" + resolvedUrlPath + "\""); 119 } 120 this.cache.put(key, resolvedUrlPath); 121 } 122 123 return resolvedUrlPath; 124 } 125 126}