org.springframework.web.servlet.resource.CachingResourceTransformer Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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
*
* https://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.servlet.resource;
import java.io.IOException;
import jakarta.servlet.http.HttpServletRequest;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
/**
* A {@link org.springframework.web.servlet.resource.ResourceTransformer} that checks a
* {@link org.springframework.cache.Cache} to see if a previously transformed resource
* exists in the cache and returns it if found, and otherwise delegates to the resolver
* chain and saves the result in the cache.
*
* @author Rossen Stoyanchev
* @since 4.1
*/
public class CachingResourceTransformer implements ResourceTransformer {
private static final Log logger = LogFactory.getLog(CachingResourceTransformer.class);
private final Cache cache;
public CachingResourceTransformer(Cache cache) {
Assert.notNull(cache, "Cache is required");
this.cache = cache;
}
public CachingResourceTransformer(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;
}
@Override
public Resource transform(HttpServletRequest request, Resource resource, ResourceTransformerChain transformerChain)
throws IOException {
Resource transformed = this.cache.get(resource, Resource.class);
if (transformed != null) {
logger.trace("Resource resolved from cache");
return transformed;
}
transformed = transformerChain.transform(request, resource);
this.cache.put(resource, transformed);
return transformed;
}
}