Question

I got working server and client applications, they work perfect while sending small files, but when I try to send for example movie file that is 700mb over socket it gives me

Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space

I searched the internet and found some tutorials on sending large files, but couldn’t quite understand them, but I think my porblem is in writing file.

This is the code that server uses to write my file:

output = new FileOutputStream(directory + "/" + fileName);
            long size = clientData.readLong();
            byte[] buffer = new byte[1024];

            while (size > 0 && (bytesRead = clientData.read(buffer, 0, (int) Math.min(buffer.length, size))) != -1) {
                output.write(buffer, 0, bytesRead);
                size -= bytesRead;
            }
            output.close();

And here is the code that my client uses to send a file:

byte[] fileLength = new byte[(int) file.length()];  

        FileInputStream fis = new FileInputStream(file);  
        BufferedInputStream bis = new BufferedInputStream(fis);

        DataInputStream dis = new DataInputStream(bis);     
        dis.readFully(fileLength, 0, fileLength.length);  

        OutputStream os = socket.getOutputStream();  

        //Sending size of file.
        DataOutputStream dos = new DataOutputStream(os);   
        dos.writeLong(fileLength.length);
        dos.write(fileLength, 0, fileLength.length);     
        dos.flush();  

        socket.close();  

Answer 1

It gives you OutOfMemoryError because you are trying to read the entire file into memory before sending it. This is 100% completely and utterly unnecessary. Just read and write chunks, much as you are doing in the receiving code.