org.springframework.web.reactive.resource.CachingResourceResolver Maven / Gradle / Ivy
/*
* 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 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.
* The codings configured here are generally expected to match those
* configured on {@link EncodedResourceResolver#setContentCodings(List)}.
*
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 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 getContentCodings() {
return Collections.unmodifiableList(this.contentCodings);
}
@Override
protected Mono resolveResourceInternal(@Nullable ServerWebExchange exchange,
String requestPath, List 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 resolveUrlPathInternal(String resourceUrlPath,
List 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));
}
}