MarshallingEncoder Class — netty Architecture

Source Code

codec-marshalling/src/main/java/io/netty/handler/codec/marshalling/MarshallingEncoder.java lines 37–66

@Sharable
public class MarshallingEncoder extends MessageToByteEncoder<Object> {

    private static final byte[] LENGTH_PLACEHOLDER = new byte[4];
    private final MarshallerProvider provider;

    /**
     * Creates a new encoder.
     *
     * @param provider the {@link MarshallerProvider} to use
     */
    public MarshallingEncoder(MarshallerProvider provider) {
        super(Object.class);
        this.provider = provider;
    }

    @Override
    protected void encode(ChannelHandlerContext ctx, Object msg, ByteBuf out) throws Exception {
        Marshaller marshaller = provider.getMarshaller(ctx);
        int lengthPos = out.writerIndex();
        out.writeBytes(LENGTH_PLACEHOLDER);
        ChannelBufferByteOutput output = new ChannelBufferByteOutput(out);
        marshaller.start(output);
        marshaller.writeObject(msg);
        marshaller.finish();
        marshaller.close();

        out.setInt(lengthPos, out.writerIndex() - lengthPos - 4);
    }
}