Develop Reference

The server is sending data through the socket, but the client is not receving it (Java)

I am writing a file storage and transfer system using Java. Here's the code on the client side to receive a file:
public static void receiveFile(Socket socket) throws IOException{
String fileLocation="/home/limafoxtrottango/Downloads/receivedFile";
int bytesRead=0;
int current = 0;
FileOutputStream fileOutputStream = null;
BufferedOutputStream bufferedOutputStream = null;
try {
// receive file
byte [] byteArray = new byte [60022386];
System.out.println("Waiting to receive a file...");
//reading file from socket
InputStream inputStream = socket.getInputStream();
fileOutputStream = new FileOutputStream(fileLocation);
bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
bytesRead = inputStream.read(byteArray,0,byteArray.length); //copying file from socket to byteArray
current = bytesRead;
do {
bytesRead =inputStream.read(byteArray, current, (byteArray.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bufferedOutputStream.write(byteArray, 0 , current); //writing byteArray to file
bufferedOutputStream.flush(); //flushing buffers
System.out.println("File " + fileLocation + " downloaded ( size: " + current + " bytes read)");
} catch(SocketException e){
System.out.println("Some error occured");
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally {
if (fileOutputStream != null) fileOutputStream.close();
if (bufferedOutputStream != null) bufferedOutputStream.close();
if (socket != null) socket.close();
}
}
While receiving a file, I get the following error:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at java.io.BufferedOutputStream.write(BufferedOutputStream.java:128)
at Test.receiveFile(Test.java:211)
at Test.main(Test.java:70)
Note: The error is in the following line of the code:
bufferedOutputStream.write(byteArray, 0 , current);
After debugging, I found-out that the client does not have any data in it's input stream, and hence, the read() method always returns -1 (eof). But the server is sending the file successfully.
Here is the code for the server:
public static void sendFile(Socket socket, String fileLocation)
{
FileInputStream fileInputStream = null;
BufferedInputStream bufferedInputStream = null;
OutputStream outputStream = null;
File file = new File (fileLocation);
byte [] byteArray = new byte [(int)file.length()];
try {
socket=new Socket(socket.getInetAddress(),port_no);
fileInputStream = new FileInputStream(file);
bufferedInputStream = new BufferedInputStream(fileInputStream);
bufferedInputStream.read(byteArray,0,byteArray.length); // copied file into byteArray
//sending file through socket
outputStream = socket.getOutputStream();
System.out.println("Sending " + fileLocation + "( size: " + byteArray.length + " bytes)");
outputStream.write(byteArray,0,byteArray.length); //copying byteArray to socket
outputStream.flush(); //flushing socket
System.out.println("Done sending!");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
And here is my call to the above method:
sendFile(clientSocket, "/home/limafoxtrottango/Downloads/serverDownloads/"+sender);
The thing is that the server is successfully writing the byte into the stream, but the client doesn't seem to have any data in it's input stream.

https://docs.oracle.com/javase/7/docs/api/java/io/InputStream.html#read(byte[],%20int,%20int)
inputStream.read(byteArray,0,byteArray.length); may return -1 in some cases as given in documentation above. Please cater for such situations.
In addition, I would suggest to use solution given here for both client and server: Efficient way to write InputStream to a File in Java (Version 6)
Client code:
final Path destination = Paths.get(fileLocation);
try (
final InputStream in = socket.getInputStream();
) {
Files.copy(in, destination);
}
Server code:
try (
final InputStream in = new FileInputStream(fileLocation);
) {
Files.copy(in, socket.getOutputStream());
}
Kind regards,
Bala

The server isn't sending anything, contrary to your title. It is closing the connection immediately, so bytesRead is initially -1 and never changes, and you aren't defending against that, so you get the ArrayIndexOutOfBoundsException.
However in the code you posted, the server is sending something but never closing the socket, which is another bug you need to fix. It is also ignoring the count returned by FileInputStream.read() and assuming it filled the buffer, which isn't part of the specification.
So either this is not the real server code or you are connecting to something else, or the server got an IOException that you haven't mentioned.
It's curious that you use two different pieces of code for copying. The standard way to copy a stream in Java is this:
char buffer = new char[8192]; // or whatever size you prefer > 0
int count;
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
Use this at both ends. There is no need for heroically sized buffers, or buffers the size of the file, or assuming that the file size fits into an int.

Sending file from one client to another client using socket in java

Hello everyone ,
I am trying to develop the application for transfering/sending the file like SKYPE works.So I am using socket for transfering file from one computer(client) to another computer(client) .I am able to transfer file from one client to server using this. code.But when I try to send the same file from server to second client.It is transfering with 0 byte also give socket close exception so I try to create new socket object at client side.So Now the Exception not coming but file not transfering to client.After debugging I found that the file is successfully sent to client by server but at client side socket is not able to read the data and waiting for data.I can’t find any better solution.If anyone knows anything about this Please tell me.If you have any other solution for file transfer than also tell me.Thanks in advance
Below is my code
Server code:
public class ChatServer
{
serversocket = new ServerSocket(1436);
thread = new Thread(this);
thread.start();
/*************Thread Implementation***************/
public void run()
{
/*********Accepting all the client connections and create a seperate thread******/
while(thread != null)
{
try
{
/********Accepting the Server Connections***********/
socket = serversocket.accept();
/******* Create a Seperate Thread for that each client**************/
chatcommunication = new ChatCommunication(this,socket);
thread.sleep(THREAD_SLEEP_TIME);
}
catch(InterruptedException _INExc) { ExitServer(); }
catch(IOException _IOExc) { ExitServer(); }
}
}
protected void SendGroupFile(Socket ClientSocket, String FileName,String GroupName,String UserName) throws IOException
{
try
{
// receive file from Client
byte [] mybytearray = new byte [filesize];
InputStream is = socket.getInputStream();
FileOutputStream fos = new FileOutputStream(Filepath);
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead;
do {
bytesRead =is.read(mybytearray, current, (mybytearray.length-current));
System.out.println("Reading Bytes server"+bytesRead);
if(bytesRead >= 0)
current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray,0,current);
bos.flush();
bos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/***** Function To Send a File to Client **********/
protected void SendGroupFileClient(Socket ClientSocket, String FileName,String GroupName,String UserName)
{
try {
int m_userListSize = userarraylist.size();
clientobject = GetClientObject(GroupName);
if(clientobject != null)
for(G_ILoop = 0; G_ILoop < m_userListSize; G_ILoop++)
{
clientobject = (ClientObject) userarraylist.get(G_ILoop);
if((clientobject.getGroupName().equals(GroupName)) && (!(clientobject.getUserName().equals(UserName))))
{
{
File myFile = new File (Filepath);
byte [] mybytearray = new byte [(int)myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
os = socket.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
os.close();
}
}catch(IOException _IOExc)
{
_IOExc.printStackTrace();
}
}
}
ChatCommunication .java
public class ChatCommunication implements Runnable,CommonSettings
{
Thread thread;
Socket socket;
DataInputStream inputstream;
String RFC;
ChatServer Parent;
/********Initialize the Socket to the Client***********/
ChatCommunication(ChatServer chatserver,Socket clientsocket)
{
Parent = chatserver;
socket = clientsocket;
try
{
inputstream = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
}catch(IOException _IOExc) { }
thread = new Thread(this);
thread.start();
}
public void run()
{
while(thread != null)
{
try {
RFC = inputstream.readLine();
if(RFC.startsWith("FILEGRUP"))
{
Parent.SendGroupFile(socket,RFC.substring(9,RFC.indexOf("!")),RFC.substring(RFC.indexOf("!")+1,RFC.indexOf("*")),RFC.substring(RFC.indexOf("*")+1));
}
if(RFC.startsWith("FILEGET"))
{
Parent.SendGroupFileClient(socket,RFC.substring(8,RFC.indexOf("!")),RFC.substring(RFC.indexOf("!")+1,RFC.indexOf("*")),RFC.substring(RFC.indexOf("*")+1));
}
}catch(Exception _Exc)
{
Parent.RemoveUserWhenException(socket);QuitConnection();
}
}
}
Client code
class Client extends JFrame
{
ServerName="192.168.1.103";
ServerPort=1436;
Client()
{
socket = new Socket(ServerName,ServerPort);
SendGroupFileToServer(Filepath,SelectedGroup);
}
/*******Function To Send File To Server and receiving the file ***********/
protected void SendGroupFileToServer(String FileName, String ToGroup)
{
try {
dataoutputstream.writeBytes(FileName.concat("!").concat(ToUser)+"\r\n");
//send file to sever
File myFile = new File (FileName.substring(9));
byte [] mybytearray = new byte [(int)myFile.length()];
FileInputStream fis = new FileInputStream(myFile);
BufferedInputStream bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
OutputStream os = socket.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
os.close();
System.out.println("File successfully Sended to server");
}catch(IOException _IoExc) { QuitConnection(QUIT_TYPE_DEFAULT);}
try {
socket1 = new Socket(ServerName,ServerPort); //Creating new Socket
dataoutputstream = new DataOutputStream(socket1.getOutputStream());
dataoutputstream.writeBytes("FILEGET"+FileName.concat("!").concat(ToGroup+"*"+UserName)+"\r\n"); //sending string to server
} catch (IOException e1) {
e1.printStackTrace();
}
// receive file sended by server
byte [] mybytearray = new byte [filesize];
InputStream is;
try {
is = socket1.getInputStream();
FileOutputStream fos = new FileOutputStream(Filepath);
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(mybytearray,0,mybytearray.length);
current = bytesRead; //up to this working fine
do {
bytesRead =is.read(mybytearray, current, (mybytearray.length-current)); //not reading the file data sent by server just waiting and not go ahead
if(bytesRead >= 0)
current += bytesRead;
} while(bytesRead > -1);
bos.write(mybytearray,0,current);
bos.flush();
bos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

There are so many problems here that it is difficult to know where to start.
The thread.sleep() in the accept() loop is literally a waste of time. It serves no useful purpose except possibly to throttle the rate at which clients are accepted. If that wasn't your intention, don't do it.
All you are doing when you catch an exception is exiting the server without even printing the exception message. So when something goes wrong, as it is here, you can't possibly know what it was. Don't do that.
readLine() returns null at EOS, on which you must close the socket, stop reading, and exit the thread. You aren't testing that, and you are therefore omitting all three of those required steps. Don't do that.
You are constructing a DataInputStream around a BufferedInputStream for use when reading commands, but you aren't passing it to the methods that process those commands. You are just passing the socket. You are therefore losing data. Don't do that. Every part of the program must use the same input stream or reader for the socket.
You are reading the entire file into memory. This (a) assumes the file size fits into an int; (b) does not scale to large files; (c) wastes space, and (d) adds latency. Don't do that.
You are ignoring the result of the read() into that buffer and assuming it was filled. You can't do that. The correct way to copy streams in Java is shown below. This works with a buffer of any size, e.g. 8192, for an input of any length, and doesn't require you to buffer the entire input into memory. You can use this loop at both the client when sending the file and at the server when receiving it.
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
Similarly to (4) above, you are using a DataOutputStream around a BufferedOutputStream for some things and the socket output stream directly for others. Don't do that. All parts of the program must the same output stream or writer for the socket.
You don't need to flush() before close(); it happens automatically.
For some reason after sending the file you are creating a new connection and sending another command. You aren't even closing the connection afterwards. The server will have no easy way of knowing that this connection and this command referred to the file just sent in the code above. It is also redundant, as the receipt of the final EOS tells the server that the file has been sent successfully. Don't do this. If you need to send more information with the file, send it first, before the file, on the same connection.
The reference you cite exhibits many of the above issues. Make an effort to find a reputable starting point.

This is the solution. Please Apply this logic to your code.
I am able to send a file from server to client and client to server.
Check the following code to send the file from Client to Server. It is working great.
If you have any issues let me know.
Server Side Code:
public class ServerRecieveFile {
public static void main(String[] args) throws IOException {// TODO Auto-enerated method stub int filesize=1022386;
int bytesRead; int currentTot= ;
ServerSocket serverSocket=new ServerSocket(15123);
Socket socket=rverSocket.accept();
byte [] bytearray = new byte [filesize];
InputStream is=socket.getInputStream();
File copyFileName=new File("c:/Files Sockets/2.txt");
FileOutputStream fos = new FileOutputStream(copyFileName);
BufferedOutputStream bos = new BufferedOutputStream(fos);
bytesRead = is.read(bytearray,0,bytearray.length);
currentTot = bytesRead;
do {
bytesRead =is.read(bytearray, currentTot, (bytearray.length-currentTot)); if(bytesRead >= 0)
currentTot += bytesRead;
} while(bytesRead > -1);
bos.write(bytearray, 0 , currentTot);
bos.flush();
bos.close();
socket.close();
}
}
Client Side code:
public class ClientSendFile {
public static void main(String[] args) throws UnknownHostException, IOException {// TODO Auto-generated method stub
Client client=new Client();
Socket socket = new Socket(InetAddress.getLocalHost(),15123);
System.out.println("Accepted connection : " + socket);
File transferFile = new File ("c:/Files Sockets/1.txt");
byte [] bytearray = new byte (int)transferFile.length()];
FileInputStream fin = new FileInputStream(transferFile);
BufferedInputStream bin = new BufferedInputStream(fin);
bin.read(bytearray,0,bytearray.length);
OutputStream os = socket.getOutputStream();
System.out.println("Sending Files...");
os.write(bytearray,0,bytearray.length);
os.flush();
socket.close();
System.out.println("File transfer complete");
}
}

Java Android Sockets

I'm currently working on an Android app which sends an string and a file to a java server app running on remote computer. This java server app should find the index on the file and send back the value of this index (The file structure is: index value. Example: 1 blue) The file is properly sent and received on the remote machine and I have a method which finds the value of the received index on the file. But when I'm trying to send the found value back to the phone I get an exception (closed socket), but I'm not closing the socket or any buffer. I'm not sure if the socket which is closed is the mobile app socket or the java server app socket. I'm using the same socket I use to send to receive (which is the way to work on Android). Sending the answer back to the phone is what my project is missing and is what I need help in. Here is my code:
Client app (Android app):
private class HeavyRemProcessing extends AsyncTask<String, Void, String>
{
protected String doInBackground(String... urls)
{
begins = System.currentTimeMillis();
remoteExecution();
ends= System.currentTimeMillis();
procTime=ends-begins;
aux= Long.toString(procTime);
return aux;
} //doInBackground() ends
protected void onPostExecute(String time)
{
textView1.setText("Result: "+result+". Processing Time: "+time+" milisecs");
}// onPostExecute ends
} //HeavyRemProcessing ends
public void executor(View view)
{
key="74FWEJ48DX4ZX8LQ";
HeavyRemProcessing task = new HeavyRemProcessing();
task.execute(new String[] { "????" });
} //executor() ends
public void remoteExecution()
{
// I have fixed IP and port I just deleted
String ip; //SERVER IP
int port; // SERVER PORT
try
{
cliSock = new Socket(ip, port);
file= new File("/mnt/sdcard/download/Test.txt");
long length = file.length();
byte[] bytes = new byte[(int) length];
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
BufferedOutputStream out = new BufferedOutputStream(cliSock.getOutputStream());
BufferedReader in = new BufferedReader(new InputStreamReader(cliSock.getInputStream()));
int count;
key=key+"\r\n";
out.write(key.getBytes());
while ((count = bis.read(bytes)) > 0)
{
out.write(bytes, 0, count);
} //It works perfectly until here
//// PROBABLY HERE IS THE PROBLEM:
out.flush();
out.close();
fis.close();
bis.close();
result= in.readLine(); //RECEIVE A STRING FROM THE REMOTE PC
}catch(IOException ioe)
{
// Toast.makeText(getApplicationContext(),ioe.toString() + ioe.getMessage(),Toast.LENGTH_SHORT).show();
}
}catch(Exception exp)
{
//Toast.makeText(getApplicationContext(),exp.toString() + exp.getMessage(),Toast.LENGTH_SHORT).show();
}
} //remoteExecution ends
Java Server App (Remote PC)
public void receivingFile()
{
System.out.println("Executing Heavy Processing Thread (Port 8888).");
try
{
serverSocket = new ServerSocket(8888);
InputStream is = null;
OutputStream os= null;
FileOutputStream fos = null;
BufferedOutputStream bos = null;
BufferedOutputStream boSock =null;
DataOutputStream dataOutputStream=null;
int bufferSize = 0;
try
{
socket = serverSocket.accept();
System.out.println("Heavy Processing Task Connection from ip: " + socket.getInetAddress());
} catch (Exception ex)
{
System.out.println("Can't accept client connection: "+ex);
}
try
{
is = socket.getInputStream();
dataOutputStream = new DataOutputStream(socket.getOutputStream());
bufferSize = socket.getReceiveBufferSize();
}
catch (IOException ex)
{
System.out.println("Can't get socket input stream. ");
}
try
{
fos = new FileOutputStream(path);
bos = new BufferedOutputStream(fos);
}
catch (FileNotFoundException ex)
{
System.out.println("File not found. ");
}
byte[] bytes = new byte[bufferSize];
int count;
System.out.println("Receiving Transfer File!.");
while ((count = is.read(bytes)) > 0)
{
bos.write(bytes, 0, count);
}
System.out.println("File Successfully Received!.");
fos.close();
bos.flush();
bos.close();
is.close();
result= obj.searchIndex();
System.out.println("Found: "+result); //This correctly print the found value
dataOutputStream.writeUTF(result);
dataOutputStream.flush();
dataOutputStream.close();
System.out.println("Data sent back to the Android Client. ");
} catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
} // receivingFile() ends
Please if someone can help me I will really appreciate it. I'm thinking is something probably related with the buffers and the socket. My java server app throws an exception: "Closed Socket"... Thanks for your time,
Alberto.

I think your problem is that you closing the outputstream before closing the inputstream. This is a bug in android. Normally in java closing outputstream only flushes the data and closing inputstream causes the connection to be closed. But in android closing the outputstream closes the connection. That is why you are getting closed socket exception,
Put the statements
out.flush();
out.close();
after
result=in.readLine();
or just avoid those statements(out.flush and out.close). I had also faced a similar problem. See my question

socket closed exception after transferring one file from server to client

I am implementing two programs; Client and Server, and client asks for a file from server to download in local file system.
After downloading one file, the client should be able to download another file if it wishes to..
However after it downloads the file, Server gives me an exception says
java.net.SocketException: Socket closed
Here's my code..
Client:
byte[] aByte = new byte[0];
int bytesRead;
String msg;
FileOutputStream fos = null;
BufferedOutputStream bos = null;
while (!(msg = input.readLine()).equals("end")) {
String myFolderName = "ServerFolder";
File folder=new File(myFolderName);
if (!folder.exists()){
folder.mkdir();
}
System.out.println("file downloading");
try {
System.out.println("1");
fos = new FileOutputStream("ServerFolder/"+fileToDownload);
bos = new BufferedOutputStream(fos);
System.out.println("MSG: "+msg);
bytesRead = in.read(aByte, 0, aByte.length);
System.out.println("2");
do {
baos.write(aByte);
bytesRead = in.read(aByte);
} while (bytesRead != -1);
System.out.println("3");
bos.write(baos.toByteArray());
bos.flush();
} catch (IOException ex) {
System.err.println(ex.getMessage());
}
}
bos.close();
} catch (IOException ex) {
System.err.println(ex);
}
Server:
if (outToClient != null) {
System.out.println("2");
File myFile = new File(msg);
byte[] mybytearray = new byte[(int) myFile.length()];
try {
fis = new FileInputStream(myFile);
} catch (FileNotFoundException ex) {
// Do exception handling
}
System.out.println("3");
bis = new BufferedInputStream(fis);
try {
bis.read(mybytearray, 0, mybytearray.length);
System.out.println("mybytearray.length: "+(int) myFile.length());
out.write((int) myFile.length()+"\r\n");
out.write("end\r\n");
out.flush();
outToClient.write(mybytearray, 0, mybytearray.length);
outToClient.flush();
s.shutdownOutput();
outToClient.close();
System.out.println("4");
} catch (IOException ex) {
System.out.println("5");
System.err.println(ex);
}
(All connection stuff are done in the beginning of each method)
I had
s.close();
in the Server but I deleted it just in case it causes the error but its not..
I am presuming that
outToClient.close();
is not causing it either?...
Also I googled this problem and some people suggested to tell the client the size of the file before the server sends the file.. but it didn't work as well.. so I deleted that part as well(or maybe I did it wrong..)
Thanks:)

java.net.SocketException: Socket closed
This has one meaning only. You closed the socket, then you continued you use it. Possibly you are unware that closing either the input or the output stream of a Socket closes the other stream and the socket.
There are numerous other errors in your code: you are ignoring the value returned by read(); you are using unnecessary BytearrayOutputStreams when you could be writing directly to the target; etc etc. Too numerous to mention really. The canonical way to copy a stream in Java is as follows:
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
If you want to use the same connection to transfer more than one file you will have to send the length of the file ahead of the file so the peer knows when it has read all the file, using an obvious modification of the above loop. DataOutputStream.writeLong() and DataInputStream.readLong() provide the most obvious ways of doing that.

Java - Read file from Socket (while loop never ends)

My JAVA application sends a command to server (command=filename.ini). When the server receives this command it sends filename.ini contents through Socket.
The first problem I had was receiving only partial contents of the file. That happened when in the code I used while(in.available()!=0){//write bytes} because in.available() does not know how big/long the content of the file is. If I use while((numBytesRead = dis.read(buffer)) != -1){//write bytes} the loop will never terminate since the Socket connection remains always open. My question is how else can I terminate the loop once every byte has been received? Please help me I have tried everything. I understand where the mistake is but I don't know how to fix it.
The following is the part of the code I have at the moment:
public class TCPClient {
protected Socket s = null;
public DataInputStream in = null;
public TCPClient(InetAddress ipa, int port) {
Socket s1 = null;
try { //Open the socket.
s1 = new Socket(ipa.getHostAddress(), port);
} catch (IOException ex) {
System.out.println("Error opening socket!");
return;
}
s = s1;
try { //Create an input stream.
in = new DataInputStream(new BufferedInputStream(s.getInputStream()));
} catch (Exception ex) {
System.out.println("Error creating input stream!");
}
}
public synchronized byte[] receive() {
byte[] buffer = new byte[0];
ByteArrayOutputStream getBytes = new ByteArrayOutputStream();
try {
while (in.available() == 0) {
} //Wait for data.
} catch (IOException ex) {
}
try {
int numBytesRead;
buffer = new byte[1024];
while ((numBytesRead = dis.read(buffer, 0, 1024)) != -1) { //LOOP NEVER ENDS HERE BECAUSE CONNECTION IS ALWAYS OPEN
getBytes.write(buffer, 0, numBytesRead);
}
} catch (IOException ex) {
}
return (getBytes.toByteArray());
}
}

You need to define a micro protocol to say the receiver how long is the file, or just close the connection on the server after finishing sending the file. First method is preferred, since it is a little bit more robust. On the client you should have a timeout too in order to avoid to wait forever in case of network problems.
Clarification for micro protocol: before sending the file itself send a 32 (or 64 if needed) bit integer containing the file length. The client should read that integer and then start retrieving the file.