001    // Copyright 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.services.assets;
016    
017    import org.apache.tapestry5.services.assets.CompressionStatus;
018    import org.apache.tapestry5.services.assets.StreamableResource;
019    import org.apache.tapestry5.services.assets.StreamableResourceProcessing;
020    import org.apache.tapestry5.services.assets.StreamableResourceSource;
021    
022    /**
023     * Specialization of {@link SRSCachingInterceptor} that only attempts to cache
024     * compressed resources.
025     */
026    public class SRSCompressedCachingInterceptor extends SRSCachingInterceptor
027    {
028        public SRSCompressedCachingInterceptor(StreamableResourceSource delegate)
029        {
030            super(delegate);
031        }
032    
033        /**
034         * Return true only if the resource is compressed.
035         */
036        @Override
037        protected boolean isCacheable(StreamableResource resource)
038        {
039            return resource.getCompression() == CompressionStatus.COMPRESSED;
040        }
041    
042        /**
043         * Returns true just when the processing enables compression.
044         */
045        @Override
046        protected boolean enableCache(StreamableResourceProcessing processing)
047        {
048            return processing == StreamableResourceProcessing.COMPRESSION_ENABLED;
049        }
050    }