CODEWITHSUNDEEP
javamultithreadingsocketsnetwork-programming
cscan
cscan

Reputation: 3850

Java: Address already in use

I'm trying to create a simple class that can is able to send files over a network. Basically, this class is created once on each machine, a separate listening thread is started, and it can send and receive files. At this point I've hard-coded the other addresses (to a loopback) and the file-locs in order to simplify testing.

Here's my class:

public class ConnectionHandler  extends Thread{

    private ServerSocket sSocket;
    private Socket socket;

    public ConnectionHandler(){
        try {
            this.sSocket = new ServerSocket(6533);
            this.socket = new Socket("127.0.0.1", 6533);

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e){
            e.printStackTrace();
        }
    }

    public void sendFile(File f) {
        try {
            int count;
            byte[] buffer = new byte[1024];

            BufferedInputStream in = new BufferedInputStream(new FileInputStream(f));
            OutputStream out = socket.getOutputStream();

            while ((count = in.read(buffer)) > 0)
            {
              out.write(buffer, 0, count);
            }

            out.flush();
            out.close();
            in.close();
            socket.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void run(){

        try {
            int count;
            byte[] buffer = new byte[1024];

            InputStream in = sSocket.accept().getInputStream();
            BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(location));

            while ((count = in.read(buffer)) > 0)
            {
              out.write(buffer, 0, count);
              out.flush();
            }

            out.close();
            in.close();
            sSocket.close();

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

However, I'm running into a 'Address already in use' error and cannot figure out the issue within my code. Additionally, I recognize that my 'run' thread terminates after one transmission, this is intentional for testing. I plan on implementing a more robust thread that can handle multiple connections, etc.

Upvotes: 0

Views: 597

Answers (2)

Gray
Gray

Reputation: 116918

However, I'm running into a 'Address already in use' error and cannot figure out the issue within my code

Any chance you are trying to fork multiple ConnectionHandler threads? That would try to start multiple server sockets on more 6533 and the 2nd one would throw an exception.

Typically the main thread starts the server socket and a ConnectionHandler is forked after a connection is accepted. Something like:

// main or server thread
ServerSocket  serverSocket = new ServerSocket(6533);
try {
   while (!shuttingDown) {
       Socket socket = serverSocket.accept();
       // better would be to use an ExecutorService thread-pool here
       new Thread(new ConnectionHandlerRunnable(socket)).start();
   }
} finally {
   serverSocket.close();
}

Upvotes: 0

user207421
user207421

Reputation: 311039

Something else is listening to port 6533. netstat will tell you what.

Upvotes: 1

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