Issue in getting data from a tcp port using netty4 component

I am using Camel Netty4 component to listen data on a TCP port. Below is my code:

public class TcpListener {


    public static void main(String hh[]) throws Exception{

        MyMessageDecoder byteDecoder = new MyMessageDecoder();
        SimpleRegistry reg = new SimpleRegistry();
        reg.put("decoder", byteDecoder);
        CamelContext context = new DefaultCamelContext(reg);

        context.addRoutes(new RouteBuilder() {
            public void configure() {

                from("netty4:tcp://0.0.0.0:5150?decoder=#decoder")
                .to("file://C:/Users/Rahul/Desktop?fileName=tcpOutput.txt");
            }
        });

        context.start();
    }

}

class MyMessageDecoder extends ByteToMessageDecoder {

    static FileWriter writer;
    static {
        try {
            writer = new FileWriter("C:/Users/Rahul/Desktop/tcpOutputNew1.txt");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void decode(ChannelHandlerContext context, ByteBuf buffer, List<Object> out) throws Exception {

        if (buffer.readableBytes() < 1) {
            return;
        }

        byte[] bytes = new byte[1];
        buffer.readBytes(bytes);

        MyMessage myMessage = new MyMessage(bytes);
        System.out.println(bytes[0]);
        System.out.println(Integer.toBinaryString(bytes[0]));
        System.out.println(Integer.toHexString(bytes[0]));
        System.out.println(myMessage);

        out.add(myMessage);
    }
}

class MyMessage {

    protected byte data1;

    public MyMessage(byte[] data) {
        data1 = data[0];
    }

    public String toString() {
        return "MyMessage: { " + this.data1 +" }";
    }
}

In my code I am trying to read 1 byte at a time because in each byte I will receive some information about a device in Hex format. Now the issue is, for some of bytes I am data like : ffffff80. In this 80 is the correct information which I wanted to receive but it is appended with ffffff. I am getting this for some of the bytes received.
How can I resolve this or how can I ignore these unwanted bytes appended.