/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.reactive.resource; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.stream.Collectors; import reactor.core.publisher.Mono; import org.springframework.cache.Cache; import org.springframework.cache.CacheManager; import org.springframework.core.io.Resource; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.StringUtils; import org.springframework.web.server.ServerWebExchange; /** * A {@link ResourceResolver} that resolves resources from a {@link Cache} or * otherwise delegates to the resolver chain and caches the result. * * @author Rossen Stoyanchev * @author Brian Clozel * @since 5.0 */ public class CachingResourceResolver extends AbstractResourceResolver { /** * The prefix used for resolved resource cache keys. */ public static final String RESOLVED_RESOURCE_CACHE_KEY_PREFIX = "resolvedResource:"; /** * The prefix used for resolved URL path cache keys. */ public static final String RESOLVED_URL_PATH_CACHE_KEY_PREFIX = "resolvedUrlPath:"; private final Cache cache; private final List<String> contentCodings = new ArrayList<>(EncodedResourceResolver.DEFAULT_CODINGS); public CachingResourceResolver(Cache cache) { Assert.notNull(cache, "Cache is required"); this.cache = cache; } public CachingResourceResolver(CacheManager cacheManager, String cacheName) { Cache cache = cacheManager.getCache(cacheName); if (cache == null) { throw new IllegalArgumentException("Cache '" + cacheName + "' not found"); } this.cache = cache; } /** * Return the configured {@code Cache}. */ public Cache getCache() { return this.cache; } /** * Configure the supported content codings from the * {@literal "Accept-Encoding"} header for which to cache resource variations. * <p>The codings configured here are generally expected to match those * configured on {@link EncodedResourceResolver#setContentCodings(List)}. * <p>By default this property is set to {@literal ["br", "gzip"]} based on * the value of {@link EncodedResourceResolver#DEFAULT_CODINGS}. * @param codings one or more supported content codings * @since 5.1 */ public void setContentCodings(List<String> codings) { Assert.notEmpty(codings, "At least one content coding expected"); this.contentCodings.clear(); this.contentCodings.addAll(codings); } /** * Return a read-only list with the supported content codings. * @since 5.1 */ public List<String> getContentCodings() { return Collections.unmodifiableList(this.contentCodings); } @Override protected Mono<Resource> resolveResourceInternal(@Nullable ServerWebExchange exchange, String requestPath, List<? extends Resource> locations, ResourceResolverChain chain) { String key = computeKey(exchange, requestPath); Resource cachedResource = this.cache.get(key, Resource.class); if (cachedResource != null) { String logPrefix = exchange != null ? exchange.getLogPrefix() : ""; logger.trace(logPrefix + "Resource resolved from cache"); return Mono.just(cachedResource); } return chain.resolveResource(exchange, requestPath, locations) .doOnNext(resource -> this.cache.put(key, resource)); } protected String computeKey(@Nullable ServerWebExchange exchange, String requestPath) { StringBuilder key = new StringBuilder(RESOLVED_RESOURCE_CACHE_KEY_PREFIX); key.append(requestPath); if (exchange != null) { String codingKey = getContentCodingKey(exchange); if (StringUtils.hasText(codingKey)) { key.append("+encoding=").append(codingKey); } } return key.toString(); } @Nullable private String getContentCodingKey(ServerWebExchange exchange) { String header = exchange.getRequest().getHeaders().getFirst("Accept-Encoding"); if (!StringUtils.hasText(header)) { return null; } return Arrays.stream(StringUtils.tokenizeToStringArray(header, ",")) .map(token -> { int index = token.indexOf(';'); return (index >= 0 ? token.substring(0, index) : token).trim().toLowerCase(); }) .filter(this.contentCodings::contains) .sorted() .collect(Collectors.joining(",")); } @Override protected Mono<String> resolveUrlPathInternal(String resourceUrlPath, List<? extends Resource> locations, ResourceResolverChain chain) { String key = RESOLVED_URL_PATH_CACHE_KEY_PREFIX + resourceUrlPath; String cachedUrlPath = this.cache.get(key, String.class); if (cachedUrlPath != null) { logger.trace("Path resolved from cache"); return Mono.just(cachedUrlPath); } return chain.resolveUrlPath(resourceUrlPath, locations) .doOnNext(resolvedPath -> this.cache.put(key, resolvedPath)); } }