Thread: Sending and Receiving File

Hi,
Recently I have been trying to send and receive stuff over network. I have two computers and I was practicing with them. Sending a simple text was easy, but file was not easy.
I kept trying but failed. So, I found an example on the Internet end tried to understand it.
This is the receiver side of the code:

import java.net.*;
import java.io.*;
 
public class FileClient{
  public static void main (String [] args ) throws IOException {
    int filesize=6022386; // filesize temporary hardcoded
 
    long start = System.currentTimeMillis();
    int bytesRead;
    int current = 0;
    // localhost for testing
    Socket sock = new Socket("127.0.0.1",13267);
    System.out.println("Connecting...");
 
    // receive file
    byte [] mybytearray  = new byte [filesize];
    InputStream is = sock.getInputStream();
    FileOutputStream fos = new FileOutputStream("source-copy.pdf");
    BufferedOutputStream bos = new BufferedOutputStream(fos);
    bytesRead = is.read(mybytearray,0,mybytearray.length);
    current = bytesRead;
 
    // thanks to A. Cádiz for the bug fix
    do {
       bytesRead = is.read(mybytearray, current, (mybytearray.length-current));
       if(bytesRead >= 0) current += bytesRead;
    } while(bytesRead > -1);
 
    bos.write(mybytearray, 0 , current);
    bos.flush();
    long end = System.currentTimeMillis();
    System.out.println(end-start);
    bos.close();
    sock.close();
  }
}

They define int filesize=6022386; and use this as the array length, if I am not wrong. How do they know this?

Possibly (About being poorly written). I realized that it does not save anything into the file. So I put a sysout in every line. It gets stuck here:

bytesRead = is.read(mybytearray,0,mybytearray.length);

I waited for 5 minutes and the file was 1 kb.
I think I lack knowledge about I/O. Because I do not even know how to fix this. The connecting part is very easy, but sending and receiving are not.

So you suggest that I could read 32 bytes and write it, and do this in a loop.

Although I felt a little lack of knowledge in myself, I'll have a try. And maybe re-read I/O topics. Thanks

Thanks for the tips
My procedure for testing network stuff goes like this: localhost, then my network ip, then the other computer. Never tried but assuming the right ip and port are provided, a code which is working on localhost can work on anywhere, I guess.

Anyway, I just tried to write a method but I was clueless. So I am reading a book right now. I'll post here when I figure things out (Or if I can't).

--- Update ---

I managed to send files. But considering the examples I saw so far, I think although I was successful, it may not be always the case. Can you please tell me what else should I consider in this code? (Added throws Exception to simplify learning)

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
 
public class Lol {
 
	public void readClient() throws Exception{//Start server button	
		ServerSocket serverSocket = new ServerSocket(clientPort);		
		Socket mySocket = serverSocket.accept();
		BufferedInputStream bis = new BufferedInputStream(mySocket.getInputStream());
		BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("D:/As.exe"));
		int read;
		while((read = bis.read())> -1){
			bos.write(read);
		}
		bos.flush();
		bos.close();
		bis.close();
	}
 
	public void sendData() throws Exception {
		 Socket mySocket = new Socket(serverIp, Integer.parseInt(serverPort));	 
		 BufferedInputStream bis = new BufferedInputStream(new FileInputStream("D:/Default.exe"));
		 BufferedOutputStream bos = new BufferedOutputStream(mySocket.getOutputStream());
		 int read;
		 while((read = bis.read())> -1){
			 bos.write(read);
		 }
		 bis.close();
		 bos.close();
 
	}
}

Thanks Norm! That will be my next objective. But, can you spot any potential problems with that? Because the others were so long and some of them were so complex, I thought I might be missing some cases where this code will fail.

It is working flawless and it is weird for me to say, but I kinda wanted this to fail. Because comparing the examples and my code, I feel like they are testing the connection for something, but I neither see it in the code nor think anything about it.
I have tried it with different computers of course. Wireless or cable network like it matters. I think I'll leave it as it is for now except for trying to write more than one byte at a time. Well, while I was writing this, I figured they might be testing the total bytes or something...
Anyways, thanks.