Simple java file transfer

FileClient.java

package client;

import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.Socket;

public class FileClient {
	
	private Socket s;
	
	public FileClient(String host, int port, String file) {
		try {
			s = new Socket(host, port);
			sendFile(file);
		} catch (Exception e) {
			e.printStackTrace();
		}		
	}
	
	public void sendFile(String file) throws IOException {
		DataOutputStream dos = new DataOutputStream(s.getOutputStream());
		FileInputStream fis = new FileInputStream(file);
		byte[] buffer = new byte[4096];
		
		while (fis.read(buffer) > 0) {
			dos.write(buffer);
		}
		
		fis.close();
		dos.close();	
	}
	
	public static void main(String[] args) {
		FileClient fc = new FileClient("localhost", 1988, "cat.jpg");
	}

}

FileServer.java

package server;

import java.io.DataInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class FileServer extends Thread {
	
	private ServerSocket ss;
	
	public FileServer(int port) {
		try {
			ss = new ServerSocket(port);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public void run() {
		while (true) {
			try {
				Socket clientSock = ss.accept();
				saveFile(clientSock);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	private void saveFile(Socket clientSock) throws IOException {
		DataInputStream dis = new DataInputStream(clientSock.getInputStream());
		FileOutputStream fos = new FileOutputStream("testfile.jpg");
		byte[] buffer = new byte[4096];
		
		int filesize = 15123; // Send file size in separate msg
		int read = 0;
		int totalRead = 0;
		int remaining = filesize;
		while((read = dis.read(buffer, 0, Math.min(buffer.length, remaining))) > 0) {
			totalRead += read;
			remaining -= read;
			System.out.println("read " + totalRead + " bytes.");
			fos.write(buffer, 0, read);
		}
		
		fos.close();
		dis.close();
	}
	
	public static void main(String[] args) {
		FileServer fs = new FileServer(1988);
		fs.start();
	}

}

How would i modify this to allow for more than one client to be connected to the server and when a client sends a file, the server sends it to the other users.

when I transfer a small file, it work fine.
however, when I transfer a big file, client throws:
java.net.SocketException: Broken pipe

why? hope have a answer, thanks

change

while (fis.read(buffer) > 0) {
    dos.write(buffer);
}

to

int read;
while ((read=fis.read(buffer)) > 0) {
	dos.write(buffer,0,read);
}

-> now it works

Will it make the file read faster if its done using multiple threads using FileChannel?

int read;
while ((read=fis.read(buffer)) > 0) {
	dos.write(buffer,0,read);
}

Worked for me, thank you very much!

What is the filesize in serverside bro ? why did you set it equal 15123 ?

You guys need to set the size for the buffer as the same as your file, also fileSize, the best solution.