java send file using sockets

Question

I am trying to send a file from one computer to another using Java. I have written the code below, it works fine if both sender and receiver are started in the same computer

Answer 1

On the client side you write up to count bytes and send them:

while ((count = in.read(buffer)) > 0) {
  out.write(buffer, 0, count);

on the server side you read up to count bytes - but then you write the whole buffer to file!

while((count=in.read(buffer)) > 0){
  fos.write(buffer);

Just change it to:

fos.write(buffer, 0, count);

and you'll be on the safe side. BTW your program has another small bug: read() can return 0 which doesn't mean InputStream ended. Use >= instead:

count = in.read(buffer)) >= 0

---

Have you considered IOUtils.copy(InputStream, OutputStream) from Apache Commons? It would reduce your whole while loops to:

OutputStream out = socket.getOutputStream();
InputStream in = new FileInputStream(myFile);
IOUtils.copy(in, out);
socket.close();

Less code to write, less code to test. And buffering is done internally.