protected void initChannel(SocketChannel ch) throws Exception {

                    ChannelPipeline p = ch.pipeline();

                    p.addLast(new ObjectEncoder());

                    p.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(null)));

                    p.addLast(new ObjectEchoServerHandler());

                }

public class ObjectEchoServerHandler extends ChannelInboundHandlerAdapter {

    @Override

    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        ctx.write(msg);

    }

    @Override

    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        ctx.flush();

    }

    @Override

    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

        cause.printStackTrace();

        ctx.close();

    }

}

protected void initChannel(SocketChannel ch) throws Exception {

                    ChannelPipeline p = ch.pipeline();

                    p.addLast(new ObjectEncoder());

                    p.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(null)));

                    p.addLast(new ObjectEchoClientHandler());

                }

public class ObjectEchoClientHandler extends ChannelInboundHandlerAdapter {

    private final List<Integer> firstMessage;

    public ObjectEchoClientHandler() {//每个channel（connection）都会new该handler

        firstMessage = new ArrayList<Integer>(ObjectEchoClient.SIZE);

        for (int i = 0; i < ObjectEchoClient.SIZE; i++) {

            firstMessage.add(Integer.valueOf(i));

        }

    }

    @Override

    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        ctx.writeAndFlush(firstMessage);

    }

    @Override

    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        //Echo back the received object to the server.

        ctx.write(msg);

    }

    @Override

    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        ctx.flush();

    }

    @Override

    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

        cause.printStackTrace();

        ctx.close();

    }

}