Why socket send only 1KB (425B) of data?

Question

I am learning sockets and now I want to write file transfer program. I have server part and client part. Server part contains 2 ports: 5000 (commands) and 5001 (files). Now I want to send a file via socket and when I did something is wrong because only 425B of data is sending.

Here is client send method:

private void sendFile(Socket socket) {
    File file2 = new File("C:\\Users\\barte\\Desktop\\dos.png");
    byte[] bytes = new byte[16 * 1024];
    System.out.println(file2.exists());
    try (InputStream inputStream = new FileInputStream(file2);
        OutputStream outputStream = socket.getOutputStream();
        OutputStream secondOutput = new FileOutputStream("C:\\Users\\barte\\Desktop\\received\\dos.png")) {
        int count;
        while ((count = inputStream.read(bytes)) > 0) {
            outputStream.write(bytes, 0, count);
            secondOutput.write(bytes, 0, count);
        }
        socket.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

As you can see (image below) I am writing this file also locally and everything is ok, all of 73KB of data is writed.

Now, on server side I am trying to receive this file:

case SEND: {
   new Thread(() -> {
     printWriter.println("Server is receiving files right now...");
     try (ServerSocket serverSocket = new ServerSocket(5001)) {
       while (true) {
        new FilesTransfer(serverSocket.accept()).start();
       }
     } catch (IOException e) {
        e.printStackTrace();
     }
     }).start();
     break;
   }

And inside FilesTransfer run method:

@Override
public void run() {
    System.out.println("Hello there");
    try {
        InputStream inputStream = inSocket.getInputStream();
        OutputStream outputStream = new FileOutputStream("C:\\Users\\barte\\Desktop\\received\\file");
        byte[] bytes = new byte[16 * 1024];
        int count;
        while ((count = inputStream.read()) > 0) {
            outputStream.write(bytes, 0, count);
        }
        outputStream.close();
        inputStream.close();
        inSocket.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Where is a bug? Why only empty bytes are sending when locally everything it's fine?

Answer 1

The problem is:

while ((count = inputStream.read()) > 0) {

Your code uses InputStream.read(), which reads individual bytes (or -1 when end-of-stream). Right now, you are reading individual bytes, interpreting that as a length, and then writing that number of 0x00 bytes from bytes to the file. This stops when you read a 0x00 byte from the stream.

You need to change this to use InputStream.read(byte[]):

while ((count = inputStream.read(bytes)) != -1) {

That is, you need to pass bytes in, and check for the result being unequal to -1, not if it is greater than zero (0), although read(byte[]) will only return 0 if the passed in byte array has length zero, so that is not a real concern.