java – BufferUnderflowException？ here?

I am writing a small UDP server in Java When the server receives a command ('get_video '), it reads a file ('video. Raw') and sends it to the client

This is my code:

public class ServeurBouchon {

    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {

        byte[] buff = new byte[64];
        int port = 8080;
        DatagramPacket packet = new DatagramPacket(buff,buff.length);
        DatagramSocket socket = new DatagramSocket(port);

        System.out.println("Server started at 8080 ...");

        while (true) {
            socket.receive(packet);
            new ThreadVideo(socket,packet).run();
        }

    }

    public static class ThreadVideo extends Thread {

        private DatagramSocket socket;
        private DatagramPacket packet;

        public ThreadVideo(DatagramSocket socket,DatagramPacket packet) {
            this.packet = packet;
            this.socket = socket;
        }

        public void run() {
            String cmd = new String(packet.getData(),packet.getLength());
            System.out.println("S:CMD reçu :" + cmd);
            if ("GET_VIDEO".equals(cmd)) {
                read_and_send_video(this.packet.getAddress());
            } else if ("TIMEOUT_REQUEST".equals(cmd)) {
                return;
            } else {
                System.out.println(" Exiting ...");
                return;
            }
            System.out.println("Fin .....");
        }

        private void read_and_send_video(InetAddress address) {
            System.out.println(" reading and sending video ...");
            File file = new File("./video/video.raw");
            ByteBuffer ibb = ByteBuffer.allocate(4);
            ibb.order(ByteOrder.BIG_ENDIAN);

            FileInputStream fis = null;
            DatagramPacket pack;
            byte[] buff = new byte[4];
            System.out.println(" Sending ...");
            try {
                fis = new FileInputStream(file);
                int size = 0;
                while ( size != -1) {
                    size = fis.read(buff,buff.length);
                    System.out.println(" size = " + size);
                    ibb.put(buff);                  
                    System.out.println("Size : " + ibb.getInt());
                    int length = ibb.getInt();
                    byte[] fbuff = new byte[length];                    
                    fis.read(fbuff,length);

                    pack = new DatagramPacket(fbuff,fbuff.length,address,packet.getPort());
                    socket.send(pack);
                }

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }

}

The original file format is a continuous "size frame" The "size" variable contains the size of the next frame to be read (int) My problem is that when I read the file (in line IBB. Getint()), I get this exception:

Exception in thread "main" java.nio.BufferUnderflowException
at java.nio.Buffer.nextGetIndex(Buffer.java:480)
at java.nio.HeapByteBuffer.getInt(HeapByteBuffer.java:336)
at fr.sar.dss.bouchon.ServeurBouchon$ThreadVideo.read_and_send_video(ServeurBouchon.java:75)
at fr.sar.dss.bouchon.ServeurBouchon$ThreadVideo.run(ServeurBouchon.java:48)
at fr.sar.dss.bouchon.ServeurBouchon.main(ServeurBouchon.java:29)

Maybe I made a mistake, but someone can tell me where my mistake is?

Thansk's help;)

Solution

This reads two integers

System.out.println("Size : " + ibb.getInt());
int length = ibb.getInt();

Use this:

int length = ibb.getInt();
System.out.println("Size : " + length);