gistfile1.txt

public class Gps103ProtocolEncoder extends OneToOneEncoder {
    private static final Charset CHARSET = CharsetUtil.US_ASCII;
 
    private static final byte[] TURN_ON_COMAND = ",K".getBytes(CHARSET);
    private static final byte[] TURN_OFF_COMAND = ",J".getBytes(CHARSET);
 
    private static final byte[] IMEI_PREFIX = "**,imei:".getBytes(CHARSET);
 
    @Override
    protected Object encode(ChannelHandlerContext ctx, Channel channel,
            Object msg) throws Exception {
 
        if (!(msg instanceof OutgoingPacket)) {
            return msg;
        }
       
        // prefix + imei + command + optional parameters
        ChannelBuffer buffer = ChannelBuffers.buffer(35);
 
        buffer.writeBytes(IMEI_PREFIX);
 
        Device device = ChannelAttributes.device.get(channel);
        buffer.writeBytes(CHARSET.encode(device.getImei()));
 
        if (msg == LightControl.TURN_ON) {
            buffer.writeBytes(TURN_ON_COMAND);
        } else if (msg == LightControl.TURN_OFF) {
            buffer.writeBytes(TURN_OFF_COMAND);
        }
 
        return buffer;
    }
}