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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec.http;

import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.compression.ZlibWrapper;
import io.netty.util.internal.StringUtil;

/**
 * Compresses an {@link HttpMessage} and an {@link HttpContent} in {@code gzip} or
 * {@code deflate} encoding while respecting the {@code "Accept-Encoding"} header.
 * If there is no matching encoding, no compression is done.  For more
 * information on how this handler modifies the message, please refer to
 * {@link HttpContentEncoder}.
 */
public class HttpContentCompressor extends HttpContentEncoder {

    private final int compressionLevel;
    private final int windowBits;
    private final int memLevel;

    /**
     * Creates a new handler with the default compression level (6),
     * default window size (15) and default memory level (8).
     */
    public HttpContentCompressor() {
        this(6);
    }

    /**
     * Creates a new handler with the specified compression level, default
     * window size (15) and default memory level (8).
     *
     * @param compressionLevel
     *        {@code 1} yields the fastest compression and {@code 9} yields the
     *        best compression.  {@code 0} means no compression.  The default
     *        compression level is {@code 6}.
     */
    public HttpContentCompressor(int compressionLevel) {
        this(compressionLevel, 15, 8);
    }

    /**
     * Creates a new handler with the specified compression level, window size,
     * and memory level..
     *
     * @param compressionLevel
     *        {@code 1} yields the fastest compression and {@code 9} yields the
     *        best compression.  {@code 0} means no compression.  The default
     *        compression level is {@code 6}.
     * @param windowBits
     *        The base two logarithm of the size of the history buffer.  The
     *        value should be in the range {@code 9} to {@code 15} inclusive.
     *        Larger values result in better compression at the expense of
     *        memory usage.  The default value is {@code 15}.
     * @param memLevel
     *        How much memory should be allocated for the internal compression
     *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
     *        memory.  Larger values result in better and faster compression
     *        at the expense of memory usage.  The default value is {@code 8}
     */
    public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
        if (compressionLevel < 0 || compressionLevel > 9) {
            throw new IllegalArgumentException(
                    "compressionLevel: " + compressionLevel +
                    " (expected: 0-9)");
        }
        if (windowBits < 9 || windowBits > 15) {
            throw new IllegalArgumentException(
                    "windowBits: " + windowBits + " (expected: 9-15)");
        }
        if (memLevel < 1 || memLevel > 9) {
            throw new IllegalArgumentException(
                    "memLevel: " + memLevel + " (expected: 1-9)");
        }
        this.compressionLevel = compressionLevel;
        this.windowBits = windowBits;
        this.memLevel = memLevel;
    }

    @Override
    protected Result beginEncode(HttpResponse headers, String acceptEncoding) throws Exception {
        String contentEncoding = headers.headers().get(HttpHeaders.Names.CONTENT_ENCODING);
        if (contentEncoding != null &&
            !HttpHeaders.Values.IDENTITY.equalsIgnoreCase(contentEncoding)) {
            return null;
        }

        ZlibWrapper wrapper = determineWrapper(acceptEncoding);
        if (wrapper == null) {
            return null;
        }

        String targetContentEncoding;
        switch (wrapper) {
        case GZIP:
            targetContentEncoding = "gzip";
            break;
        case ZLIB:
            targetContentEncoding = "deflate";
            break;
        default:
            throw new Error();
        }

        return new Result(
                targetContentEncoding,
                new EmbeddedChannel(ZlibCodecFactory.newZlibEncoder(
                        wrapper, compressionLevel, windowBits, memLevel)));
    }

    @SuppressWarnings("FloatingPointEquality")
    protected ZlibWrapper determineWrapper(String acceptEncoding) {
        float starQ = -1.0f;
        float gzipQ = -1.0f;
        float deflateQ = -1.0f;
        for (String encoding: StringUtil.split(acceptEncoding, ',')) {
            float q = 1.0f;
            int equalsPos = encoding.indexOf('=');
            if (equalsPos != -1) {
                try {
                    q = Float.valueOf(encoding.substring(equalsPos + 1));
                } catch (NumberFormatException e) {
                    // Ignore encoding
                    q = 0.0f;
                }
            }
            if (encoding.contains("*")) {
                starQ = q;
            } else if (encoding.contains("gzip") && q > gzipQ) {
                gzipQ = q;
            } else if (encoding.contains("deflate") && q > deflateQ) {
                deflateQ = q;
            }
        }
        if (gzipQ > 0.0f || deflateQ > 0.0f) {
            if (gzipQ >= deflateQ) {
                return ZlibWrapper.GZIP;
            } else {
                return ZlibWrapper.ZLIB;
            }
        }
        if (starQ > 0.0f) {
            if (gzipQ == -1.0f) {
                return ZlibWrapper.GZIP;
            }
            if (deflateQ == -1.0f) {
                return ZlibWrapper.ZLIB;
            }
        }
        return null;
    }
}