Develop Reference

Getting extra bytes in received file using java scoket

I have implemented a file transfer program using java socket. In this program, a file is sent from the client and its then downloaded in the Server. The program works almost correctly but the problem is the length of the received byte is always greater than the byte length sent from the client. for example, I sent 678888589 bytes from the client, but when I check the length of the received file at the server, I got 678925260 bytes. And for that reason, I am getting different checksum on the server side.
Here is my code:
Client Class:
public class Client
{
final static int ServerPort = 1234;
public static final int BUFFER_SIZE = 1024 * 50;
private static byte[] buffer;
public static void main(String args[]) throws UnknownHostException, IOException
{
Scanner scn = new Scanner(System.in);
buffer = new byte[BUFFER_SIZE];
for(int i=0;i<8;i++) {
Socket s1 = new Socket(ip, ServerPort);
DataOutputStream dos1 = new DataOutputStream(s1.getOutputStream());
SendMessage message = new SendMessage(s1, "test.mp4",dos1);
Thread t = new Thread(message);
System.out.println("Adding this client to active client list");
t.start();
}
}
}
class SendMessage implements Runnable{
String file_name;
Socket s;
public final int BUFFER_SIZE = 1024 * 50;
private byte[] buffer;
DataOutputStream dos;
public SendMessage(Socket sc,String file_name,DataOutputStream dos) {
this.file_name = file_name;
this.s=sc;
buffer = new byte[BUFFER_SIZE];
this.dos = dos;
}
#Override
public void run() {
File file = new File(file_name);
try {
sendFile(file, dos);
dos.close();
while(true) {
}
} catch (IOException e1) {
e1.printStackTrace();
}
}
public void sendFile(File file, DataOutputStream dos) throws IOException {
byte[] buffer = new byte[BUFFER_SIZE+1];
if(dos!=null&&file.exists()&&file.isFile())
{
FileInputStream input = new FileInputStream(file);
dos.writeLong(file.length());
System.out.println(file.getAbsolutePath());
int read = 0;
int totalLength = 0;
while ((read = input.read(buffer)) != -1) {
dos.write(buffer);
totalLength +=read;
System.out.println("length "+read);
}
input.close();
System.out.println("File successfully sent! "+totalLength);
}
}
}
Server Class
// Server class
public class Server
{
// Vector to store active clients
static Vector<ClientHandler> ar = new Vector<>();
// counter for clients
static int i = 0;
public static void main(String[] args) throws IOException
{
// server is listening on port 1234
ServerSocket ss = new ServerSocket(1234);
Socket s;
// running infinite loop for getting
// client request
while (true)
{
// Accept the incoming request
s = ss.accept();
System.out.println("New client request received : " + s);
// obtain input and output streams
DataInputStream dis = new DataInputStream(s.getInputStream());
DataOutputStream dos = new DataOutputStream(s.getOutputStream());
System.out.println("Creating a new handler for this client...");
// Create a new handler object for handling this request.
ClientHandler mtch = new ClientHandler(s,"client " + i, dis, dos);
// Create a new Thread with this object.
Thread t = new Thread(mtch);
System.out.println("Adding this client to active client list");
// add this client to active clients list
ar.add(mtch);
// start the thread.
t.start();
// increment i for new client.
// i is used for naming only, and can be replaced
// by any naming scheme
i++;
}
}
}
// ClientHandler class
class ClientHandler implements Runnable
{
Scanner scn = new Scanner(System.in);
private String name;
final DataInputStream dis;
final DataOutputStream dos;
Socket s;
boolean isloggedin;
public static final int BUFFER_SIZE = 1024*50;
private byte[] buffer;
// constructor
public ClientHandler(Socket s, String name,
DataInputStream dis, DataOutputStream dos) {
this.dis = dis;
this.dos = dos;
this.name = name;
this.s = s;
this.isloggedin=true;
buffer = new byte[BUFFER_SIZE];
}
#Override
public void run() {
String received;
BufferedOutputStream out = null;
String outputFile = "out_"+this.name+".mp4";
BufferedInputStream in = null;
try {
in = new BufferedInputStream(s.getInputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
out = new BufferedOutputStream(new FileOutputStream(outputFile));
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// while (true)
// {
try
{
long length = -1;
length = dis.readLong();
if(length!=-1)System.out.println("length "+length);
// String checkSum = dis.readUTF();
// System.out.println(checkSum);
int len=0;
long totalLength = 0;
// int len = 0;
while ((len = in.read(buffer,0,BUFFER_SIZE)) > 0) {
out.write(buffer, 0, len);
totalLength+=len;
// if(len<BUFFER_SIZE)break;
// System.out.println("length "+len);
if(len<=0)break;
}
File file = new File(outputFile);
System.out.println("total length1 "+totalLength+ " dif "+(totalLength-length));
System.out.println("output length "+file.length());
} catch (IOException e) {
e.printStackTrace();
}
}
private static String checksum(String filepath, MessageDigest md) throws IOException {
// file hashing with DigestInputStream
try (DigestInputStream dis = new DigestInputStream(new FileInputStream(filepath), md)) {
while (dis.read() != -1) ; //empty loop to clear the data
md = dis.getMessageDigest();
}
// bytes to hex
StringBuilder result = new StringBuilder();
for (byte b : md.digest()) {
result.append(String.format("%02x", b));
}
return result.toString();
}
}
It would be great if anyone can tell me what I am doing wrong. also, how can I verify the checksum on serverside. Another issue is the server side code get blocked in this block.
while ((len = in.read(buffer,0,BUFFER_SIZE)) > 0) {
out.write(buffer, 0, len);
System.out.println("length "+len);
if(len<=0)break;
}
It can't break the loop unless the client is disconnected. Although the file is recieved properly.
Regards.

You made a small mistake on the client code. You were writing out the full buffer instead of what is read from the file.
while ((read = input.read(buffer)) != -1) {
dos.write(buffer,0,read);
totalLength += read;
System.out.println("length " + read);
}

Java socket is stuck on readUTF()

I'm trying to transfer files over a socket in Java, my current approach for the server is:
Create new Thread
Thread sends file name using dos.writeUTF()
Thread sends file size using dos.writeLong()
Thread sends file using dos.write()
Where each Thread represents a client and dos is an instance of DataOutputStream.
Now, on the client I'm doing the same thing but reading instead of writing:
Read file name using dis.readUTF()
Read file size using dis.readLong()
Read file using dis.read()
Where dis is an instance of DataInputStream.
The problem is: when sending one file, everything goes right, but when I try to send 3 files, one after another, it looks like the server is writing everything correctly to the stream as expected but the client (After the first file, which means this starts happening from the second file) is stuck on dis.readUTF() and can't move on.
I've tried fixing this for days but can't get anything to work.
Here's the source code:
SERVER:
Main.java
public class Main {
public static void main(String[] args) {
boolean boolDebug = true;//TODO REMOVE THIS!!
ServerSocket serverSock = null;
List<Socket> clientSocks;
List<ClientThread> clientThreads;
try {
serverSock = new ServerSocket(9090);
} catch(Exception e){
e.printStackTrace();
}
clientSocks = new ArrayList<>();
clientThreads = new ArrayList<>();
ServerSocket finalServerSock = serverSock;
System.out.println();
System.out.println("Listening for incoming connections\n");
new Thread(){
#Override
public void run() {
super.run();
while (true) {
try {
Socket newSock = finalServerSock.accept();
clientSocks.add(newSock); //FIXME Remove sockets when closed
Thread thread = new ClientThread(newSock, usr, psw);
thread.start();
clientThreads.add((ClientThread)thread);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}.start();
}
}
ClientThread.java
public class ClientThread extends Thread {
private Socket socket;
private DataInputStream inStream;
private DataOutputStream outStream;
private String dbUser;
private String dbPassword;
public ClientThread(Socket socket, String DbUser, String DbPass) {
this.socket = socket;
this.dbUser = DbUser;
this.dbPassword = DbPass;
}
#Override
public void run() {
try {
inStream = new DataInputStream(socket.getInputStream());
outStream = new DataOutputStream(socket.getOutputStream());
sendFile("a.txt");
sendFile("b.txt");
sendFile("c.txt");
} catch (Exception e) {
e.printStackTrace();
}
}
void sendFile(String file){
try {
File f = new File(file);
outStream.writeUTF(file);
outStream.writeLong(f.length());
FileInputStream fis = new FileInputStream(f);
byte[] buffer = new byte[4096];
while (fis.read(buffer) > 0) {
outStream.write(buffer);
}
fis.close();
}catch(Exception e){
e.printStackTrace();
}
}
int getSize(byte[] buffer,long remaining){
try {
return Math.toIntExact(Math.min(((long) buffer.length), remaining));
}catch(ArithmeticException e){
return 4096;
}
}
}
CLIENT:
Main.java
class Main {
static int getSize(byte[] buffer, long remaining) {
try {
return Math.toIntExact(Math.min(((long) buffer.length), remaining));
} catch (ArithmeticException e) {
return 4096;
}
}
static void saveFile(Socket clientSock,DataInputStream dis) throws IOException {
String fileName = dis.readUTF();
File f = new File(fileName);
FileOutputStream fos = new FileOutputStream(f);
byte[] buffer = new byte[4096];
long filesize = dis.readLong();
int read = 0;
int totalRead = 0;
long remaining = filesize;
while ((read = dis.read(buffer, 0, getSize(buffer, remaining))) > 0) {
totalRead += read;
remaining -= read;
System.out.println("read " + totalRead + " bytes.");
fos.write(buffer, 0, read);
}
fos.close();
}
public static void main(String[] args) throws Exception {
Socket sock = new Socket("192.168.2.17", 9090);
DataInputStream dis = new DataInputStream(sock.getInputStream());
saveFile(sock,dis);
saveFile(sock,dis);
saveFile(sock,dis);
}
}
Many thanks in advance, looking forward to fix this :(

Fixed by changing
while (fis.read(buffer) > 0) {
outStream.write(buffer);
}
to
int count;
while ((count = fis.read(buffer)) > 0) {
outStream.write(buffer, 0, count);
}
Inside ClientThread.java on the server side

sending file using UDP multicast

I have a problem where I want to send my file to my friend using UDP multicast, but when I try to run the code the output is this:
Output:
Exception in thread "main" java.lang.IllegalArgumentException: illegal length or offset
at java.net.DatagramPacket.setData(Unknown Source)
at java.net.DatagramPacket.<init>(Unknown Source)
at Source.createConnection(Source.java:44)
at Source.main(Source.java:102)
And this is my code:
import java.io.*;
import java.net.*;
public class Source {
private DatagramSocket socket = null;
private FE event = null;
private String sourceFilePath = "C:/joe's/file/text/hai.txt";
private String destinationPath = "C:/maria/file2/laboratory/";
private String hostname= "192.168.43.65";
public Source(){ }
public static void main1(String[] args)throws Exception
{
try
{
DatagramSocket s = new DatagramSocket();
byte[]line = new byte[100];
System.out.print("Enter text to send");
int len = System.in.read(line);
InetAddress dest = InetAddress.getByName("192.168.43.65");
DatagramPacket pkt = new DatagramPacket(line,len,dest,16900);
s.send(pkt);
s.close();
}
catch(Exception err){
System.err.println(err);
}
}
public void createConnection() {
try {
socket = new DatagramSocket();
byte[] incomingData = new byte[9999];
event = getFE();
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ObjectOutputStream os = new ObjectOutputStream(outputStream);
os.writeObject(event);
byte[] data = outputStream.toByteArray();
DatagramPacket sendPacket = new DatagramPacket(data, data.length, 9876);
socket.send(sendPacket);
System.out.println("File sent from AppsA");
DatagramPacket incomingPacket = new DatagramPacket(incomingData,
incomingData.length);
socket.receive(incomingPacket);
String response = new String(incomingPacket.getData());
System.out.println("Response from AppsB:" + response);
Thread.sleep(2000);
System.exit(0);
}
catch (UnknownHostException e) {
e.printStackTrace();
} catch (SocketException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public FE getFE() {
FE fileEvent = new FE();
String fileName = sourceFilePath.substring(sourceFilePath.lastIndexOf("/") + 1,
sourceFilePath.length());
String path = sourceFilePath.substring(0, sourceFilePath.lastIndexOf("/") + 1);
fileEvent.setDestinationDirectory(destinationPath);
fileEvent.setFilename(fileName);
fileEvent.setSourceDirectory(sourceFilePath);
File file = new File(sourceFilePath);
if (file.isFile())
{
try {
DataInputStream diStream = new DataInputStream(new FileInputStream(file));
long len = (int) file.length();
byte[] fileBytes = new byte[(int) len];
int read = 0;
int numRead = 0;
while (read < fileBytes.length && (numRead = diStream.read(fileBytes, read,
fileBytes.length - read)) >= 0) {
read = read + numRead;
}
fileEvent.setFileSize(len);
fileEvent.setFileData(fileBytes);
fileEvent.setStatus("Success");
} catch (Exception e) {
e.printStackTrace();
fileEvent.setStatus("Error");
}
}
else {
System.out.println("path specified is not pointing to a file");
fileEvent.setStatus("Error");
}
return fileEvent;
}
public static void main(String[] args)throws Exception {
Source app = new Source();
app.createConnection();
}
}

Your problem lies in improper use of DatagramPacket constructors:
DatagramPacket sendPacket = new DatagramPacket(data, data.length, 9876);
The above line is correct however, the code below:
DatagramPacket incomingPacket = new DatagramPacket(incomingData,
incomingData.length);
Should be this:
DatagramPacket incomingPacket = new DatagramPacket(incomingData,
9876);
The second argument in the DatagramPacket constructor is the length. You initially set the length on sendPacket to 9876

Java streams with EOFException

I wrote some client - server program, that shares data but at server side i got EOFException after reciving data. I tried to fix it on my own but it is hard to find own errors.
The error is caused by this line: Message command =(Message) serInputStream.readObject();
Here is some output from server:
java.io.EOFException
at Java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2577)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1315)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)
at transfer.Serwerus.run(Serwerus.java:42)
Server code:
import java.io.*;
import java.net.*;
public class Serwerus implements Runnable
{
public InputStream is;
public FileOutputStream fos;
public BufferedOutputStream bos;
public ObjectOutputStream serOutputStream;
public ObjectInputStream serInputStream;
ServerSocket socket;
private String clientMessage, clientFileName;
private int clientFileSize;
public Serwerus()
{
try
{
socket = new ServerSocket(6060);
System.out.println("Server started....");
}
catch(IOException e)
{
System.err.println("Error: " + e);
e.printStackTrace();
}
}
#Override
public void run()
{
try
{
Socket sock = socket.accept();
System.out.println("Client accepted");
serOutputStream = new ObjectOutputStream(sock.getOutputStream());
serInputStream = new ObjectInputStream(sock.getInputStream());
while (true)
{
Message command =(Message) serInputStream.readObject();
System.out.println("after readObject");
if (command.getCommand().startsWith("FileU"))
{
System.out.println("Name = " + command.getfileName() + ", size= " + command.getfileSize());
serOutputStream.writeObject(new Message("Bring", "", 0));
//ReciveData(socket, command.getfileName(), command.getfileSize());
}
else if(command.getCommand().startsWith("Wait"))
{
System.out.println("hohoho");
ReciveData(sock, command.getfileName(), command.getfileSize());
}
else if(command.getCommand().startsWith("Quit"))
{
System.exit(1);
}
else
{
System.out.println("Unknow");
}
}
}
catch(ClassNotFoundException | IOException ex)
{
ex.printStackTrace();
}
finally
{
try
{
serInputStream.close();
serOutputStream.close();
socket.close();
}
catch (IOException e)
{
System.err.println("Fallen on closing socket.\n Error: " + e);
}
}
}
public void SendData(Socket sock, String filePath) throws Exception
{
File myFile = new File (filePath);
System.out.println("File name = " + myFile.getName() + " File len = " + (int)myFile.length());
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 = sock.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
os.flush();
sock.close();
System.out.println("Sending finished");
}
public void ReciveData(Socket sock, String filePath, int fileSize)
{
System.out.println("Recive in progress, filesize = " + fileSize);
int bytesRead = 0, current = 0;
byte[] array = new byte[fileSize];
try
{
is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream(filePath);
bos = new BufferedOutputStream(fos);
do
{
System.out.println(bytesRead);
bytesRead = is.read(array);
current += bytesRead;
}
while(bytesRead > -1);
bos.write(array, 0 , current);
bos.flush();
bos.close();
fos.close();
// sock.close();
System.out.println("Reciveing finished");
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
public static void main (String [] args ) throws IOException
{
new Thread(new Serwerus()).start();
}
}
Client code:
import java.io.*;
import java.net.*;
public class Clientus implements Runnable
{
InputStream is;
FileOutputStream fos;
BufferedOutputStream bos;
ObjectOutputStream cliOutputStream;
ObjectInputStream cliInputStream;
Socket socket;
File actFile;
private String serverMessage, serverFileName;
private int serverFileSize;
public Clientus()
{
try
{
socket = new Socket("localhost", 6060);
cliOutputStream = new ObjectOutputStream(socket.getOutputStream());
cliInputStream = new ObjectInputStream(socket.getInputStream());
File file = new File(<filepath>);
actFile = file;
}
catch (Exception e)
{
System.err.println("Error: " + e);
e.printStackTrace();
}
}
#Override
public void run()
{
try
{
cliOutputStream.writeObject(new Message("FileU", actFile.getPath(), (int) actFile.length()));
cliOutputStream.flush();
//while (true)
//{
Message command =(Message) cliInputStream.readObject();
if (command.getCommand().startsWith("File"))
{
String name = command.getfileName();
int size = command.getfileSize();
System.out.println("Name = " + command.getfileName() + ", size= " + command.getfileSize());
if(size != 0 && !"".equals(name))
{
//ReciveData(socket, 0);
}
}
else if(command.getCommand().startsWith("Bring"))
{
cliOutputStream.writeObject(new Message("Wait", "D:\\KP2\\Serwer\\dupa.txt",(int) actFile.length()));
cliOutputStream.flush();
try
{
SendData(socket, actFile.getPath());
//this.socket.close();
}
catch (Exception ex)
{
System.err.println("Error with: SendData()");
}
}
else if(command.getCommand().startsWith("Quit"))
{
System.exit(1);
}
else
{
System.out.println("Command unknown");
}
//}
}
catch(ClassNotFoundException | IOException ex)
{
ex.printStackTrace();
}
finally
{
try
{
socket.close();
cliOutputStream.close();
cliInputStream.close();
}
catch (IOException e)
{
System.err.println("Fallen on closing socket.\n Error: " + e);
}
}
}
public void SendData(Socket sock, String filePath) throws Exception
{
byte [] mybytearray = new byte [(int) new File(filePath).length()];
FileInputStream fis = new FileInputStream(filePath);
BufferedInputStream bis = new BufferedInputStream(fis);
bis.read(mybytearray,0,mybytearray.length);
OutputStream os = sock.getOutputStream();
System.out.println("Sending...");
os.write(mybytearray,0,mybytearray.length);
fis.close();
bis.close();
os.close();
System.out.println("Sending finished");
}
public void ReciveData(Socket sock, String fileName, int fileSize)
{
int bytesRead, current = 0;
byte[] array = new byte[fileSize+1];
try
{
is = sock.getInputStream();
fos = new FileOutputStream(<file_path>);
bos = new BufferedOutputStream(fos);
bytesRead = is.read(array,0,array.length);
current = bytesRead;
do
{
bytesRead = is.read(array, current, (array.length - current));
if(bytesRead >= 0)
current += bytesRead;
}
while(bytesRead > -1);
bos.write(array, 0 , current);
bos.flush();
long end = System.currentTimeMillis();
//System.out.println("Send time: " + (end - start));
bos.close();
sock.close();
System.out.println("Reciveing finished");
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
public static void main (String [] args ) throws IOException
{
new Thread(new Clientus()).start();
}
}
Can anyone help?

Your client may be disconnected after sending data and because your server is waiting for more data, the EOFException will occurr.
To fix this problem, you can add try-catch block to catching this exception when the client disconnects.

You are using both the ObjectOutputStream and the socket's own OutputStream to send data on, and you are getting out of sync. When you send the raw data directly over the socket you aren't sending the length first, so the receiver doesn't know how many bytes belong to this transmission. In fact it just reads everything until EOS, so next time you call ObjectInputStream.readObject() it naturally gets an EOFException. To fix this:
Use the ObjectInputStream and ObjectOutputStream for everything.
Before sending the file, send its length, via writeLong().
At the receiver, when receiving the file, first get its length, via readLong(), then read exactly that many bytes from the ObjectInputStream and copy them to the file.

Threads are facing deadlock in socket program

I am developing one program in which a user can download a number of files. Now first I am sending the list of files to the user. So from the list user selects one file at a time and provides path where to store that file. In turn it also gives the server the path of file where does it exist.
I am following this approach because I want to give stream like experience without file size limitation.
Here is my code..
1) This is server which gets started each time I start my application
public class FileServer extends Thread {
private ServerSocket socket = null;
public FileServer() {
try {
socket = new ServerSocket(Utils.tcp_port);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void run() {
try {
System.out.println("request received");
new FileThread(socket.accept()).start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
2) This thread runs for each client separately and sends the requested file to the user 8kb data at a time.
public class FileThread extends Thread {
private Socket socket;
private String filePath;
public String getFilePath() {
return filePath;
}
public void setFilePath(String filePath) {
this.filePath = filePath;
}
public FileThread(Socket socket) {
this.socket = socket;
System.out.println("server thread" + this.socket.isConnected());
//this.filePath = filePath;
}
#Override
public void run() {
// TODO Auto-generated method stub
try
{
ObjectInputStream ois=new ObjectInputStream(socket.getInputStream());
try {
//************NOTE
filePath=(String) ois.readObject();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
File f = new File(this.filePath);
byte[] buf = new byte[8192];
InputStream is = new FileInputStream(f);
BufferedInputStream bis = new BufferedInputStream(is);
ObjectOutputStream oos = new ObjectOutputStream(
socket.getOutputStream());
int c = 0;
while ((c = bis.read(buf, 0, buf.length)) > 0) {
oos.write(buf, 0, c);
oos.flush();
// buf=new byte[8192];
}
oos.close();
//socket.shutdownOutput();
// client.shutdownOutput();
System.out.println("stop");
// client.shutdownOutput();
ois.close();
// Thread.sleep(500);
is.close();
bis.close();
socket.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
NOTE: here filePath represents the path of the file where it exists on the server. The client who is connecting to the server provides this path. I am managing this through sockets and I am successfully receiving this path.
3) FileReceiverThread is responsible for receiving the data from the server and constructing file from this buffer data.
public class FileReceiveThread extends Thread {
private String fileStorePath;
private String sourceFile;
private Socket socket = null;
public FileReceiveThread(String ip, int port, String fileStorePath,
String sourceFile) {
this.fileStorePath = fileStorePath;
this.sourceFile = sourceFile;
try {
socket = new Socket(ip, port);
System.out.println("receive file thread " + socket.isConnected());
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public void run() {
try {
ObjectOutputStream oos = new ObjectOutputStream(
socket.getOutputStream());
oos.writeObject(sourceFile);
oos.flush();
// oos.close();
File f = new File(fileStorePath);
OutputStream os = new FileOutputStream(f);
BufferedOutputStream bos = new BufferedOutputStream(os);
byte[] buf = new byte[8192];
int c = 0;
//************ NOTE
ObjectInputStream ois = new ObjectInputStream(
socket.getInputStream());
while ((c = ois.read(buf, 0, buf.length)) > 0) {
// ois.read(buf);
bos.write(buf, 0, c);
bos.flush();
// buf = new byte[8192];
}
ois.close();
oos.close();
//
os.close();
bos.close();
socket.close();
//Thread.sleep(500);
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
NOTE : Now the problem that I am facing is at the first time when the file is requested the outcome of the program is same as my expectation. I am able to transmit any size of file at first time. Now when the second file is requested (e.g. I have sent file a,b,c,d to the user and user has received file a successfully and now he is requesting file b) the program faces deadlock at this situation. It is waiting for socket's input stream. I put breakpoint and tried to debug it but it is not going in FileThread's run method second time. I could not find out the mistake here. Basically I am making a LAN Messenger which works on LAN. I am using SWT as UI framework.

A more basic problem.
You are only processing the first socket.
while(true) {
new FileThread(socket.accept()).start();
}

As per the suggestion of Peter Lawrey i removed all the redundant streams code from my source code. Now the changed source code is as follows and the problem remains.
1) No change in FileServer. It is as it is .
2) FileThread
public class FileThread extends Thread {
private Socket socket;
private String filePath;
public String getFilePath() {
return filePath;
}
public void setFilePath(String filePath) {
this.filePath = filePath;
}
public FileThread(Socket socket) {
this.socket = socket;
System.out.println("server thread" + this.socket.isConnected());
// this.filePath = filePath;
}
#Override
public void run() {
// TODO Auto-generated method stub
try
{
OutputStream oos = socket.getOutputStream();
oos.flush();
InputStream ois = socket.getInputStream();
byte[] buf = new byte[8192];
ois.read(buf);
filePath = new String(buf);
System.out.println(filePath);
File f = new File(this.filePath);
InputStream is = new FileInputStream(f);
int c = 0;
while ((c = is.read(buf, 0, buf.length)) > 0) {
oos.write(buf, 0, c);
oos.flush();
}
oos.close();
System.out.println("stop");
ois.close();
is.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
3) FileReceiverThread
public class FileReceiveThread extends Thread {
private String fileStorePath;
private String sourceFile;
private Socket socket = null;
public FileReceiveThread(String ip, int port, String fileStorePath,
String sourceFile) {
this.fileStorePath = fileStorePath;
this.sourceFile = sourceFile;
try {
socket = new Socket(ip, port);
System.out.println("receive file thread " + socket.isConnected());
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public void run() {
try {
OutputStream oos = socket.getOutputStream();
oos.write(sourceFile.getBytes());
oos.flush();
File f = new File(fileStorePath);
OutputStream os = new FileOutputStream(f);
byte[] buf = new byte[8192];
int c = 0;
// ************ NOTE
InputStream ois = socket.getInputStream();
while ((c = ois.read(buf, 0, buf.length)) > 0) {
os.write(buf, 0, c);
os.flush();
}
ois.close();
oos.close();
os.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
is there still something which i am missing ?