JdkZlibEncoder Class — netty Architecture

Source Code

codec-compression/src/main/java/io/netty/handler/codec/compression/JdkZlibEncoder.java lines 36–356

public class JdkZlibEncoder extends ZlibEncoder {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(JdkZlibEncoder.class);

    /**
     * Maximum initial size for temporary heap buffers used for the compressed output. Buffer may still grow beyond
     * this if necessary.
     */
    private static final int MAX_INITIAL_OUTPUT_BUFFER_SIZE;
    /**
     * Max size for temporary heap buffers used to copy input data to heap.
     */
    private static final int MAX_INPUT_BUFFER_SIZE;

    private final ZlibWrapper wrapper;
    private final Deflater deflater;
    private volatile boolean finished;
    private volatile ChannelHandlerContext ctx;

    /*
     * GZIP support
     */
    private final CRC32 crc;
    private static final byte[] gzipHeader = {0x1f, (byte) 0x8b, Deflater.DEFLATED, 0, 0, 0, 0, 0, 0, 0};
    private boolean writeHeader = true;

    static {
        MAX_INITIAL_OUTPUT_BUFFER_SIZE = SystemPropertyUtil.getInt(
                "io.netty.jdkzlib.encoder.maxInitialOutputBufferSize",
                65536);
        MAX_INPUT_BUFFER_SIZE = SystemPropertyUtil.getInt(
                "io.netty.jdkzlib.encoder.maxInputBufferSize",
                65536);

        if (logger.isDebugEnabled()) {
            logger.debug("-Dio.netty.jdkzlib.encoder.maxInitialOutputBufferSize={}", MAX_INITIAL_OUTPUT_BUFFER_SIZE);
            logger.debug("-Dio.netty.jdkzlib.encoder.maxInputBufferSize={}", MAX_INPUT_BUFFER_SIZE);
        }
    }

    /**
     * Creates a new zlib encoder with a compression level of ({@code 6})
     * and the default wrapper ({@link ZlibWrapper#ZLIB}).
     *
     * @throws CompressionException if failed to initialize zlib
     */
    public JdkZlibEncoder() {
        this(6);
    }

    /**
     * Creates a new zlib encoder with the specified {@code compressionLevel}
     * and the default wrapper ({@link ZlibWrapper#ZLIB}).
     *
     * @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}.
     *
     * @throws CompressionException if failed to initialize zlib
     */
    public JdkZlibEncoder(int compressionLevel) {
        this(ZlibWrapper.ZLIB, compressionLevel);
    }

    /**
     * Creates a new zlib encoder with a compression level of ({@code 6})
     * and the specified wrapper.
     *
     * @throws CompressionException if failed to initialize zlib
     */
    public JdkZlibEncoder(ZlibWrapper wrapper) {
        this(wrapper, 6);
    }

    /**
     * Creates a new zlib encoder with the specified {@code compressionLevel}
     * and the specified wrapper.
     *
     * @param compressionLevel
     *        {@code 1} yields the fastest compression and {@code 9} yields the