java - Large file transfer with sockets

Question

When I'm transferring a large file using socket programming, the received file is incomplete i.e. it is an mp3 file which when i play sounds weird. The code is:

Server side:

File myFile = new File("abc.mp3");
{
    Socket sock = servsock.accept();
    int packetsize=1024;
    double nosofpackets=Math.ceil(((int) myFile.length())/packetsize);
    BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myFile));
    for(double i=0;i<nosofpackets+1;i++) {
        byte[] mybytearray = new byte[packetsize];
        bis.read(mybytearray, 0, mybytearray.length);
        System.out.println("Packet:"+(i+1));
        OutputStream os = sock.getOutputStream();
        os.write(mybytearray, 0,mybytearray.length);
        os.flush();
    }
}

Client side:

int packetsize=1024;
FileOutputStream fos = new FileOutputStream("zz.mp3");
BufferedOutputStream bos = new BufferedOutputStream(fos);
double nosofpackets=Math.ceil(((int) (new File("abc.mp3")).length())/packetsize);
for(double i=0;i<nosofpackets+1;i++)
{
    InputStream is = sock.getInputStream();
    byte[] mybytearray = new byte[packetsize];
    int bytesRead = is.read(mybytearray, 0,mybytearray.length );
    System.out.println("Packet:"+(i+1));
    bos.write(mybytearray, 0,mybytearray.length);
}
sock.close();
bos.close();

On the Client side I have used new File("abc.mp3")).length just for simplicity (I could send the length of the file from the server side).

This code works perfectly if client and server are the same machine, but the file gets distorted if they are on different machines.

Answer 1

The canonical way to copy a stream in Java:

int count;
byte[] buffer = new byte[8192];
while ((count = in.read(buffer)) > 0)
{
  out.write(buffer, 0, count);
}

Works with any buffer size greater than zero. The temptation to relate the buffer size to the input size should be strenuously avoided.