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

Question

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();
    }
    } 

}

Answer 1

There are so many problems here that it is difficult to know where to start.

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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);
   }
   

7. 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.

8. You don't need to flush() before close(); it happens automatically.

9. 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.

10. The reference you cite exhibits many of the above issues. Make an effort to find a reputable starting point.

Answer 2

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");
 }
}