netty5/src/main/java/org/jboss/netty/handler/codec/http/HttpContentCompressor.java

/*
 * Copyright 2009 Red Hat, Inc.
 *
 * Red Hat licenses this file to you 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.jboss.netty.handler.codec.http;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.handler.codec.compression.ZlibEncoder;
import org.jboss.netty.handler.codec.compression.ZlibWrapper;
import org.jboss.netty.handler.codec.embedder.EncoderEmbedder;

/**
 * Decompresses an {@link HttpMessage} and an {@link HttpChunk} compressed in
 * {@code gzip} or {@code deflate} encoding.  Insert this handler after
 * {@link HttpMessageDecoder} in the {@link ChannelPipeline}:
 * <pre>
 * ChannelPipeline p = ...;
 * ...
 * p.addLast("decoder", new HttpRequestDecoder());
 * p.addLast("inflater", <b>new HttpContentDecomperssor()</b>);
 * ...
 * p.addLast("encoder", new HttpResponseEncoder());
 * p.addLast("handler", new HttpRequestHandler());
 * </pre>
 *
 * @author The Netty Project (netty-dev@lists.jboss.org)
 * @author Trustin Lee (trustin@gmail.com)
 * @version $Rev$, $Date$
 */
@ChannelPipelineCoverage("one")
public class HttpContentCompressor extends HttpContentEncoder {

    private final int compressionLevel;

    public HttpContentCompressor() {
        this(6);
    }

    public HttpContentCompressor(int compressionLevel) {
        if (compressionLevel < 0 || compressionLevel > 9) {
            throw new IllegalArgumentException(
                    "compressionLevel: " + compressionLevel +
                    " (expected: 0-9)");
        }
        this.compressionLevel = compressionLevel;
    }

    @Override
    protected EncoderEmbedder<ChannelBuffer> newContentEncoder(String acceptEncoding) throws Exception {
        ZlibWrapper wrapper = determineWrapper(acceptEncoding);
        if (wrapper == null) {
            return null;
        }

        return new EncoderEmbedder<ChannelBuffer>(new ZlibEncoder(wrapper, compressionLevel));
    }

    @Override
    protected String getTargetContentEncoding(String acceptEncoding) throws Exception {
        ZlibWrapper wrapper = determineWrapper(acceptEncoding);
        if (wrapper == null) {
            return null;
        }

        switch (wrapper) {
        case GZIP:
            return "gzip";
        case ZLIB:
            return "deflate";
        default:
            throw new Error();
        }
    }

    private ZlibWrapper determineWrapper(String acceptEncoding) {
        // FIXME: Use the Q value.
        if (acceptEncoding.indexOf("gzip") >= 0) {
            return ZlibWrapper.GZIP;
        }
        if (acceptEncoding.indexOf("deflate") >= 0) {
            return ZlibWrapper.ZLIB;
        }
        return null;
    }
}