/*
* Copyright 2002-2014 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.servlet.config.annotation;
import java.util.ArrayList;
import java.util.List;
import org.springframework.cache.Cache;
import org.springframework.cache.concurrent.ConcurrentMapCache;
import org.springframework.util.Assert;
import org.springframework.web.servlet.resource.CachingResourceResolver;
import org.springframework.web.servlet.resource.CachingResourceTransformer;
import org.springframework.web.servlet.resource.CssLinkResourceTransformer;
import org.springframework.web.servlet.resource.PathResourceResolver;
import org.springframework.web.servlet.resource.ResourceResolver;
import org.springframework.web.servlet.resource.ResourceTransformer;
import org.springframework.web.servlet.resource.VersionResourceResolver;
/**
* Assists with the registration of resource resolvers and transformers.
*
* @author Rossen Stoyanchev
* @since 4.1
*/
public class ResourceChainRegistration {
private static final String DEFAULT_CACHE_NAME = "spring-resource-chain-cache";
private final List<ResourceResolver> resolvers = new ArrayList<ResourceResolver>(4);
private final List<ResourceTransformer> transformers = new ArrayList<ResourceTransformer>(4);
private boolean hasVersionResolver;
private boolean hasPathResolver;
private boolean hasCssLinkTransformer;
public ResourceChainRegistration(boolean cacheResources) {
this(cacheResources, cacheResources ? new ConcurrentMapCache(DEFAULT_CACHE_NAME) : null);
}
public ResourceChainRegistration(boolean cacheResources, Cache cache) {
Assert.isTrue(!cacheResources || cache != null, "'cache' is required when cacheResources=true");
if (cacheResources) {
this.resolvers.add(new CachingResourceResolver(cache));
this.transformers.add(new CachingResourceTransformer(cache));
}
}
/**
* Add a resource resolver to the chain.
* @param resolver the resolver to add
* @return the current instance for chained method invocation
*/
public ResourceChainRegistration addResolver(ResourceResolver resolver) {
Assert.notNull(resolver, "The provided ResourceResolver should not be null");
this.resolvers.add(resolver);
if (resolver instanceof VersionResourceResolver) {
this.hasVersionResolver = true;
}
else if (resolver instanceof PathResourceResolver) {
this.hasPathResolver = true;
}
return this;
}
/**
* Add a resource transformer to the chain.
* @param transformer the transformer to add
* @return the current instance for chained method invocation
*/
public ResourceChainRegistration addTransformer(ResourceTransformer transformer) {
Assert.notNull(transformer, "The provided ResourceTransformer should not be null");
this.transformers.add(transformer);
if (transformer instanceof CssLinkResourceTransformer) {
this.hasCssLinkTransformer = true;
}
return this;
}
protected List<ResourceResolver> getResourceResolvers() {
if (!this.hasPathResolver) {
List<ResourceResolver> result = new ArrayList<ResourceResolver>(this.resolvers);
result.add(new PathResourceResolver());
return result;
}
return this.resolvers;
}
protected List<ResourceTransformer> getResourceTransformers() {
if (this.hasVersionResolver && !this.hasCssLinkTransformer) {
List<ResourceTransformer> result = new ArrayList<ResourceTransformer>(this.transformers);
boolean hasTransformers = !this.transformers.isEmpty();
boolean hasCaching = hasTransformers && this.transformers.get(0) instanceof CachingResourceTransformer;
result.add(hasCaching ? 1 : 0, new CssLinkResourceTransformer());
return result;
}
return this.transformers;
}
}