Fast file transfer via sockets

Question

Hi,
I have made little program that sends files via lan to my other computer using sockets (ServerSocket and Socket). When I code my program to use only FileInputStream and FileOutputStream throught the sockets I get only speed about 100Kbs even when I run them in localhost.
I would really like to have examples of faster way to send and receive files throught sockets? Any samples using buffers or compressing data would be very nice. Thank you very much in advance!
Sincerely,
Lauri Lehtinen

Answer 1

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
* FileServer.java
* Created on January 18, 2005, 2:21 PM
* @author  Ian Schneider
public class FileServer {
    static class Server {
        Socket client;
        public Server() throws Exception {
            ServerSocket s = new ServerSocket(12345);
            while (true) {
                client = s.accept();
                File dest = new File(System.getProperty("java.io.tmpdir"),"transfer.tmp");
                InputStream data = client.getInputStream();
                OutputStream out = new FileOutputStream(dest);
                byte[] bytes = new byte[1024];
                int l = 0;
                int cnt = 0;
                long time = System.currentTimeMillis();
                while ( (l = data.read(bytes)) >= 0) {
                    cnt += l;
                    out.write(bytes,0, l);
                int kb = cnt / 1024;
                int sec = (int) (System.currentTimeMillis() - time) / 1000;
                System.out.println("transfered " + kb/sec);
                out.flush();
                out.close();
                client.close();
    static void writeToServer(String fileName) throws Exception {
        Socket s = new Socket("localhost",12345);
        OutputStream out = s.getOutputStream();
        FileInputStream in = new FileInputStream(fileName);
        byte[] bytes = new byte[1024];
        int l = 0;
        while ( (l = in.read(bytes)) >= 0) {
            out.write(bytes,0,l);
        out.flush();
        out.close();
        in.close();
    public static final void main(String[] args) throws Exception {
        if (args[0].equals("server")) {
            new Server();
        } else {
            writeToServer(args[1]);
}You may see improvements by buffering these. I didn't bother testing.