ObjectInputStream catch block produces EOFException?

Question

Sorry to drag this up but I have had a good look around and I still keep getting an EOFException. I've commented everything out of my method apart from:

    File receivedFileObject;
    File newFile = new File("newlyWrittenFile.mp3");


    try{
        Socket socket = new Socket(SERVER_IP, PORT);

        try{
        ObjectInputStream incommingData = new ObjectInputStream(socket.getInputStream());

All I'm trying to do is pass a file, txt or mp3 from the server to the client - I don't even try to call readObject() on the ObjectInputStream and yet I still get EOFException? How can I reach the end of a file I haven't tried to read? In actual fact I wish I was trying to read a text file line by line, because I know how to do that perfectly fine. I just want to receive an Object, cast it to a file and write it to the file system but for some reason my catch block :

        } catch (IOException e){
            System.out.println("Incomming data assignment error : " + e);   
        }

prints out :

Incomming data assignment error : java.io.EOFException

I have been trying to follow along with the server code listed in this forum post. Basically from the server I use the following lines to write the file to the client:

        if (myFile.exists()) {
        ObjectOutputStream oos=new ObjectOutputStream(client.getOutputStream());

        oos.writeObject(myFile);
    }

I would be really grateful if someone could explain how to fix what feels like a stupid error on my part - Thanks in advance!

Where's the code where you are writing to the ObjectOutputStream? — Jon Lin, Aug 09 '12 at 02:44

score 2 · Accepted Answer · answered Aug 09 '12 at 02:53

2

An ObjectOutputStream is used for serializing a java object to a stream. It is unlikely that you want to do this.

If you want to "pass a file", that probably means you want to "pass the contents of the file", so just to this:

FileOutputStream newFile = new FileOutputStream("newlyWrittenFile.mp3");
InputStream input = socket.getInputStream();
byte[] bytes = // pseudo code for reading all bytes from input
newFile.write(bytes); // pseudo code for writing to file
newFile.close();

You might find apache common-io library IOUtils class methods quite handy to read and write your data easily

answered Aug 09 '12 at 02:53

Bohemian

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Thanks for this reply but my end goal is to actually stream mp3's over a network as opposed to waiting for entire files to download. Am I rite in saying a stream is the correct technology to use just I don't have much experience am eager to get things done. – James C Aug 09 '12 at 02:57
Yes use a stream, but do *not* use an ObjectOutputStream. There must be 1000's of examples on the web for sending bytes over a socket - just use google. You'll basically want to "pump" a `FileInputStream` to a socket's `OutputStream`. Apache's IOUtils can do that too. – Bohemian Aug 09 '12 at 13:01

score 1 · Answer 2 · answered Aug 09 '12 at 02:59

1

If you check the javadoc of ObjectInputStream:

A serialization stream header is read from the stream and verified.

So creating the object does trigger a read.

answered Aug 09 '12 at 02:59

assylias

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Ah I see, that's interesting. So what can I do to stop it generating the exception? How can I put anything "down the pipe" so to speak without this happening ? – James C Aug 09 '12 at 03:04

ObjectInputStream catch block produces EOFException?

2 Answers2