MarshallingDecoder Class — netty Architecture

Source Code

codec-marshalling/src/main/java/io/netty/handler/codec/marshalling/MarshallingDecoder.java lines 33–87

public class MarshallingDecoder extends LengthFieldBasedFrameDecoder {

    private final UnmarshallerProvider provider;

    /**
     * Creates a new decoder whose maximum object size is {@code 1048576}
     * bytes.  If the size of the received object is greater than
     * {@code 1048576} bytes, a {@link StreamCorruptedException} will be
     * raised.
     *
     */
    public MarshallingDecoder(UnmarshallerProvider provider) {
        this(provider, 1048576);
    }

    /**
     * Creates a new decoder with the specified maximum object size.
     *
     * @param maxObjectSize  the maximum byte length of the serialized object.
     *                       if the length of the received object is greater
     *                       than this value, {@link TooLongFrameException}
     *                       will be raised.
     */
    public MarshallingDecoder(UnmarshallerProvider provider, int maxObjectSize) {
        super(maxObjectSize, 0, 4, 0, 4);
        this.provider = provider;
    }

    @Override
    protected Object decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
        ByteBuf frame = (ByteBuf) super.decode(ctx, in);
        if (frame == null) {
            return null;
        }

        Unmarshaller unmarshaller = provider.getUnmarshaller(ctx);
        ByteInput input = new ChannelBufferByteInput(frame);

        try {
            unmarshaller.start(input);
            Object obj = unmarshaller.readObject();
            unmarshaller.finish();
            return obj;
        } finally {
            // Call close in a finally block as the ReplayingDecoder will throw an Error if not enough bytes are
            // readable. This helps to be sure that we do not leak resource
            unmarshaller.close();
        }
    }

    @Override
    protected ByteBuf extractFrame(ChannelHandlerContext ctx, ByteBuf buffer, int index, int length) {
        return buffer.slice(index, length);
    }
}