Getting “java.io.EOFException” after sending a file throught socket

Question

I'm trying to implement basic communication through sockets, what I have now is:

• server start's to listen on socket,

   this.serverSocket_ = new ServerSocket(this.serverPort_); clientSocket = this.serverSocket_.accept(); 

• client connects, and server starts separate thread to operate with that client,

• both open Object output and input streams,

   out = new ObjectOutputStream(clientSocket_.getOutputStream()); out.flush(); in = new ObjectInputStream(clientSocket_.getInputStream()); 

• client sends two i Doubles, String and Long over that stream (flushes after each one),

    out.writeObject(conf_); out.flush(); out.writeObject(supp_); out.flush(); out.writeObject(separator_); out.flush(); out.writeObject(new Long(dataFile_.length())); out.flush(); 

• server succesfully receives those objects over previously opened streams,

   conf_ = (Double) in_.readObject(); supp_ = (Double) in_.readObject(); separator_ = (String) in_.readObject(); fileSize_ = (Long) in_.readObject(); 

• and now "the hard part",

• clients wants to send a file so opens different output stream (not object output stream) and sends the file,

   FileInputStream fis = new FileInputStream(dataFile_); BufferedInputStream bis = new BufferedInputStream(fis); OutputStream os = clientSocket_.getOutputStream(); while (current < fileSize) { bytesRead = bis.read(mybytearray, 0, mybytearray.length); if (bytesRead >= 0) { os.write(mybytearray, 0, mybytearray.length); current += bytesRead; } progressBar_.setValue(current); progressBar_.repaint(); } os.flush(); 

• the server receives the file (also uses simple input stream instead ObjectInputStream),

   int bytesRead; int current = 0; tmpFile_ = File.createTempFile("BasketAnalysis", "rec.dat"); byte[] mybytearray = new byte[fileSize]; InputStream is = clientSocket_.getInputStream(); FileOutputStream fos = new FileOutputStream(tmpFile_); BufferedOutputStream bos = new BufferedOutputStream(fos); bytesRead = is.read(mybytearray, 0, mybytearray.length); current = bytesRead; do { bytesRead = is.read(mybytearray, current, (mybytearray.length - current)); if (bytesRead >= 0) current += bytesRead; } while ((bytesRead > -1) && (current < fileSize)); bos.write(mybytearray, 0, current); bos.flush(); bos.close(); 

• so far everything works fine, file is received, but now server performs some time consuming processing on that file after which sends response with whe results to client,

   String resp = new String("Some processing result..."); out_.writeObject(resp); out_.flush(); 

• the client is supposed to receive the result what finishes the whole communication,

   String message = (String) in.readObject(); Console.info("server > " + message); 

Unfortunately, that last step on client side fails with exception:

    java.io.EOFException
        at java.io.ObjectInputStream$BlockDataInputStream.peekByte(Unknown Source)
        at java.io.ObjectInputStream.readObject0(Unknown Source)
        at java.io.ObjectInputStream.readObject(Unknown Source)
        at basketAnalysis.client.Client.run(Client.java:74)
        at java.lang.Thread.run(Unknown Source)

I want client to block on waiting for server response after sending the file, but it suddenly finishes with the exception after sending the file. I am pretty sure that I do something wrong with switching between simple streams and Object streams.

Does anybody know what should I change to haave it working?

Thank you in advance!

Answer 1

I think your basic misunderstanding is here:

clients wants to send a file so opens different output stream

 OutputStream os = clientSocket_.getOutputStream(); 

That doesn't open a different output stream - that will get another reference to the same output stream which you've already got wrapped in the ObjectOutputStream . If you want two streams of data, you'll need to open two separate connections.