001// Copyright 2013 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
015package org.apache.tapestry5.internal.services.assets;
016
017import org.apache.tapestry5.services.assets.AssetChecksumGenerator;
018import org.apache.tapestry5.services.assets.CompressionStatus;
019import org.apache.tapestry5.services.assets.StreamableResource;
020
021import java.io.BufferedOutputStream;
022import java.io.ByteArrayOutputStream;
023import java.io.IOException;
024import java.io.OutputStream;
025import java.util.zip.GZIPOutputStream;
026
027/**
028 * GZip compressed representation of a {@link StreamableResource}.
029 *
030 * @since 5.4
031 */
032public class CompressedStreamableResource extends StreamableResourceImpl
033{
034    public CompressedStreamableResource(StreamableResource base, AssetChecksumGenerator assetChecksumGenerator) throws IOException
035    {
036        super(base.getDescription(), base.getContentType(), CompressionStatus.COMPRESSED, base.getLastModified(), compressContent(base), assetChecksumGenerator);
037
038        assert base.getCompression() == CompressionStatus.COMPRESSABLE;
039    }
040
041    private static BytestreamCache compressContent(StreamableResource resource) throws IOException
042    {
043        ByteArrayOutputStream compressed = new ByteArrayOutputStream(resource.getSize());
044        OutputStream compressor = new BufferedOutputStream(new GZIPOutputStream(compressed));
045
046        resource.streamTo(compressor);
047
048        compressor.close();
049
050        return new BytestreamCache(compressed);
051    }
052}