Transfering Files using Sockets

Question

Hello, im new to Java network. Im trying to build a client-server application that reads a file, converts it to bytes and writes it to socket. A server application then gets the bytes, and writes the file to the remote location.
It seems whatever i do results to errors.
Any ideas what might be the fault?
Regards
Client
========
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
import java.net.UnknownHostException;
public class DataHandler {
     static Socket toServer;
     static byte[] bytes;
     static DataOutputStream out;
     public DataHandler(byte[] bytesReturned) {
          bytes = bytesReturned;
     public static void performActions(File fileGiven) throws IOException {
          try {
               System.out.println("class CH");
               toServer = new Socket("localhost", 18583);
               readInput(fileGiven);
               sendData();
          catch (UnknownHostException ex) {
               System.err.println(ex);
          catch (IOException ex) {
               System.err.println(ex);
          finally{
               closeConnection();
     private static void closeConnection() throws IOException {
          out.close();
          toServer.close();
     public static byte[] readInput(File file) throws IOException {
          InputStream is = new FileInputStream(file);
          // Get the size of the file
          long length = file.length();
          if (length > Integer.MAX_VALUE) {
               // File is too large
          // Create the byte array to hold the data
          bytes = new byte[(int) length];
          // Read in the bytes
          int offset = 0;
          int numRead = 0;
          while (offset < bytes.length
                    && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
               offset += numRead;
          // Ensure all the bytes have been read in
          if (offset < bytes.length) {
               throw new IOException("Could not completely read file "
                         + file.getName());
          // Close the input stream and return bytes
          is.close();
          System.out.println(bytes);
          return bytes;
     private static void sendData() throws IOException {
          out = new DataOutputStream(toServer.getOutputStream());
          out.write(bytes);
     public static void main (String args[]){
          File file = new File("test.pdf");
          try {
               performActions(file);
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
Server
=======
import java.io.DataInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
public class Receiver {
     static ServerSocket server;
     static Socket connection;
     static DataInputStream input;
     public static void runServer() throws Exception{
          try {
               server = new ServerSocket(18583);
               while (true){
                    getStreams();
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
          finally{
               server.close();
               connection.close();
     private static void getStreams() throws Exception {
          connection = server.accept();
          input = new DataInputStream(connection.getInputStream());
          System.out.println(input);
          byte[] store = new byte[input.readByte()];
          input.read(store);*/
          FileOutputStream fos = new FileOutputStream("received.pdf");
          fos.write(input);
          fos.close();
     public static void main (String args[]){
          try {
               runServer();
          } catch (Exception e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
}

Answer 1

Ah, thanks a lot for the replies.
It appears that i had some kind of writing to file error in server code at: fos.write(input);
Its been fixed now.
Non the less thank you very much for bothering :-)
A silly question though. How is it possible to retain filename and filetype when sending a file? i.e. instead of having a FileOutputStream writing to a predefined by a string File (i.e. File file = new File("a_picture.jpg");) being able to send any type of file and keep their current format and name?
I assume you should first send a string with the file name but the BufferedInputStream i have at the server mixes up both String and actual file bytes.
Excuse me for the long question
Kind Regards
Chris