    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.internal.services.assets;
    014
    015import org.apache.tapestry5.services.assets.AssetChecksumGenerator;
    016import org.apache.tapestry5.services.assets.CompressionStatus;
    017import org.apache.tapestry5.services.assets.StreamableResource;
    018
    019import java.io.BufferedOutputStream;
    020import java.io.ByteArrayOutputStream;
    021import java.io.IOException;
    022import java.io.OutputStream;
    023import java.util.zip.GZIPOutputStream;
    024
    025/**
    026 * GZip compressed representation of a {@link StreamableResource}.
    027 *
    028 * @since 5.4
    029 */
    030public class CompressedStreamableResource extends StreamableResourceImpl
    031{
    032    public CompressedStreamableResource(StreamableResource base, AssetChecksumGenerator assetChecksumGenerator) throws IOException
    033    {
    034        super(base.getDescription(), base.getContentType(), CompressionStatus.COMPRESSED, base.getLastModified(), compressContent(base), assetChecksumGenerator, base.getResponseCustomizer());
    035
    036        assert base.getCompression() == CompressionStatus.COMPRESSABLE;
    037    }
    038
    039    private static BytestreamCache compressContent(StreamableResource resource) throws IOException
    040    {
    041        ByteArrayOutputStream compressed = new ByteArrayOutputStream(resource.getSize());
    042        OutputStream compressor = new BufferedOutputStream(new GZIPOutputStream(compressed));
    043
    044        resource.streamTo(compressor);
    045
    046        compressor.close();
    047
    048        return new BytestreamCache(compressed);
    049    }
    050}