Simple Java Client Server Solution

import java.io.*;
import java.net.*;

public class Server {
    public static void main(String[] args) throws Exception {
       ServerSocket ss = new ServerSocket(20000);
       while(true){
          Socket s = ss.accept();
          InputStream is = s.getInputStream();
          OutputStream os = new FileOutputStream(new Random().nextInt(100000)+".file");
          byte[] b = new byte[2048];
          int n;
             while((n = is.read(b,0,b.length)) !=-1) {
               os.write(b, 0, n);
               os.flush();
             }
          os.close();
          is.close();
       }
    }
}

import java.io.*;
import java.net.*;

public class Client {
    public static void main(String[] args) throws Exception {
       Socket s = new Socket("localhost", 20000);
       OutputStream os = s.getOutputStream();
       InputStream is = new FileInputStream("filetotransfer.file");
       byte[] b = new byte[2048];
       int n;
       while((n = is.read(b,0,b.length)) !=-1) {
          os.write(b, 0, n);
          os.flush();
       }
       os.close();
       is.close();
    }
}