Correct way to send BufferedImage in object with serialization. writeObject readObject

Question

I'm trying to send an object with a BufferedImage through a socket. I now realize that I have to make that it transient, the class implement serializable, and override the writeObject and readObject methods. I think my write is correct but my read I keeps giving my an EOFException. Here is my class:

private void writeObject(ObjectOutputStream out)throws IOException{
    out.defaultWriteObject();
    //write buff with imageIO to out
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(image, "jpg", baos);
}

private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException{
    in.defaultReadObject();
    //read buff with imageIO from in
    DataInputStream dis = new DataInputStream(in);

   int len = dis.readInt();

    byte[] data = new byte[len];
    dis.readFully(data);
    dis.close();
    in.close();

    InputStream ian = new ByteArrayInputStream(data);
    image= ImageIO.read(ian);
}

I think readInt() in readObject is throwing it.

@Turing85 strangely enough it's not giving me a stack trace. Eclipse says source not found when I click on it — user234234234, Apr 25 '15 at 08:52

score 1 · Accepted Answer · edited May 23 '17 at 12:22

1

Your writeObject never writes to out. It writes to the ByteArrayOutputStream which is not used later

UPDATE See e.g. the post how list of images is serialized. You can skip the count writing/reading

edited May 23 '17 at 12:22

Community

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answered Apr 25 '15 at 08:52

StanislavL

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would ImageIO.write(image, "jpg", out); do the job? I'm sorry not too familiar with sockets yet. – user234234234 Apr 25 '15 at 08:55
finally the image bytes should be written to out. I think writing to out directly is ok but you can try – StanislavL Apr 25 '15 at 08:59
how would I get the image bytes? and write it to out exactly? – user234234234 Apr 25 '15 at 09:01

score 0 · Answer 2 · answered Apr 25 '15 at 10:17

The problem here is that you are reading things that haven't been written. If you expect to read an int, you need to write an int. Instead you are dumping the image to a byte array out out stream, which has zero effect on the serialization whatsoever.

Your code doesn't make sense.

If you write an image, write it to the object stream, and read it back the same way, with ImageIO.

NB If you are getting an exception there is certainly a stack trace somewhere.

Correct way to send BufferedImage in object with serialization. writeObject readObject

2 Answers2