Java invalid stream header Problem

Question

Hi all, im writen a client-server app, and now i´m facing a problem that I dont know how to solve:

This is the client:

try
        {

            Socket socket = new Socket(ip, port);


            ObjectOutputStream ooos = new ObjectOutputStream(socket
                    .getOutputStream());
            SendMessage message = new SendMessage();

            message.numDoc = value.numDoc;
            message.docFreq = value.docFreq;

            message.queryTerms = query;
            message.startIndex = startIndex;
            message.count = count;
            message.multiple = false;
            message.ips = null;
            message.ports = null;

            message.value = true;
            message.docFreq = value.docFreq;
            message.numDoc = value.numDoc;
            ooos.writeObject(message);


            ObjectInputStream ois = new ObjectInputStream(socket
                    .getInputStream());
            ComConstants mensajeRecibido;
            Object mensajeAux;
            String mensa = null;

            byte[] by = null;

            do
            {

                mensajeAux = ois.readObject();

                if (mensajeAux instanceof ComConstants)
                {


                    System.out.println("Thread by Thread has Search Results");

                    String test;

                    ByteArrayOutputStream testo = new ByteArrayOutputStream();

                    mensajeRecibido = (ComConstants) mensajeAux;

                    byte[] wag;

                    testo.write(
                            mensajeRecibido.fileContent, 0,
                            mensajeRecibido.okBytes);

                    wag = testo.toByteArray();


                    if (by == null) {

                        by = wag;

                    }
                    else {

                        int size = wag.length;

                          System.arraycopy(wag, 0, by, 0, size);
                    }


                } else
                {

                    System.err.println("Mensaje no esperado "
                            + mensajeAux.getClass().getName());
                    break;
                }
            } while (!mensajeRecibido.lastMessage);




            //ByteArrayInputStream bs = new ByteArrayInputStream(by.toByteArray()); // bytes es el byte[]
            ByteArrayInputStream bs = new ByteArrayInputStream(by);
            ObjectInputStream is = new ObjectInputStream(bs);
            QueryWithResult[] unObjetoSerializable = (QueryWithResult[])is.readObject();
            is.close();

            //AQUI TOCARIA METER EL QUICKSORT

            XmlConverter xce = new XmlConverter(unObjetoSerializable, startIndex, count);
            String serializedd = xce.runConverter();



        tempFinal = serializedd;

            ois.close();
            socket.close();

        } catch (Exception e)
        {
            e.printStackTrace();
        }

        i++;

        }

And this is the sender:

try
    {

        QueryWithResult[] outputLine;

        Operations op = new Operations();

        boolean enviadoUltimo=false;

        ComConstants mensaje = new ComConstants();
        mensaje.queryTerms = query;

        outputLine = op.processInput(query, value);

        //String c = new String();
        //c = outputLine.toString();
        //StringBuffer swa = sw.getBuffer();

        ByteArrayOutputStream bs= new ByteArrayOutputStream();

        ObjectOutputStream os = new ObjectOutputStream (bs);
        os.writeObject(outputLine);
        os.close();

        byte[] mybytearray =  bs.toByteArray();

        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(mybytearray); 

        BufferedInputStream bis = new BufferedInputStream(byteArrayInputStream);

        int readed = bis.read(mensaje.fileContent,0,4000);


        while (readed > -1)
        {


            mensaje.okBytes = readed;


            if (readed < ComConstants.MAX_LENGTH)
            {
                mensaje.lastMessage = true;
                enviadoUltimo=true;
            }
            else
                mensaje.lastMessage = false;

            oos.writeObject(mensaje);


            if (mensaje.lastMessage)
                break;

            mensaje = new ComConstants();
            mensaje.queryTerms = query;

            readed = bis.read(mensaje.fileContent);
        }

        if (enviadoUltimo==false)
        {
            mensaje.lastMessage=true;
            mensaje.okBytes=0;
            oos.writeObject(mensaje);
        }

        oos.close();
    } catch (Exception e)
    {
        e.printStackTrace();
    }
}

And this is the error log:

Thread by Thread has Search Results
java.io.StreamCorruptedException: invalid stream header: 20646520
at java.io.ObjectInputStream.readStreamHeader(Unknown Source)
at java.io.ObjectInputStream.<init>(Unknown Source)
at org.tockit.comunication.ServerThread.enviaFicheroMultiple(ServerThread.java:747)
at org.tockit.comunication.ServerThread.run(ServerThread.java:129)
at java.lang.Thread.run(Unknown Source)

Where at org.tockit.comunication.ServerThread.enviaFicheroMultiple(ServerThread.java:747) is this line ObjectInputStream is = new ObjectInputStream(bs); on the 1st code just after while (!mensajeRecibido.lastMessage);

Any ideas?

Answer 1

The value 20646520 is in ASCII @A.

ObjectInput/OutputStreams use a "magic" value at the beginning of the stream, to indicate it complies to the special serialization of the objects. (I think this was 0xCAFEBABE, but I'm not sure)

This means in your situation that something has already read the stream before the ObjectInputStream has the chance to read the magic, or that the stream it reads is not producted by an ObjectOutputStream;

You assign the variable by to wig (or append), which is a byte array which is not generated by an ObjectOutputStream, as far as I can tell, since it uses mensajeRecipido.fileContent. I presume mensajeRecipido.fileContent is the content of an actual file. In this running instance is not of the same format as an ObjectOutputStream, and that's why you get the stream header exception.