Java广播和侦听在同一端口上

Question

How can broadcast a message from single server to multiple clients and listen for a reply from one of the clients.

I used Multicast Programming to broadcast the message to the clients. And If i send the message from one of my clients back to the server either through TCP or UDP, I am getting a " java.net.ConnectException: Connection refused: connect " exception.

Please help me out.

Thanks in Advance.

Sender Code :

// Broadcasting the message

    msg = "This is multicast! " + counter;
                counter++;
                outBuf = msg.getBytes();

                // Send to multicast IP address and port
                InetAddress address = InetAddress.getByName("224.2.2.3");
                outPacket = new DatagramPacket(outBuf, outBuf.length, address,
                        PORT);

                socket.send(outPacket);

                System.out.println("Server sends : " + msg);

                socket.close();



                // Receiving TCP
                apSock = new Socket("131.151.88.165", 6161);
                apBuffReader = new BufferedReader(new InputStreamReader(
                        apSock.getInputStream()));
                while ((ap2Toap1 = apBuffReader.readLine()) != null) {
                    System.out.println(ap2Toap1);
                }

Receiver Code :

count++;
                inPacket = new DatagramPacket(inBuf, inBuf.length);
                socket.receive(inPacket);
                String msg = new String(inBuf, 0, inPacket.getLength());
                System.out.println("From " + inPacket.getAddress() + " Msg : "
                        + msg);

                socket.close();



                // Sending TCP
                apSock = new Socket("131.151.88.165", 6161);
                System.out.println("Hello2");
                respWriter = new PrintWriter(apSock.getOutputStream());
                System.out.println("Writing back to the server");
                respWriter.println(outBuf);
                if (respWriter != null)
                    respWriter.close();

Answer 1

There is no listening in your code. TCP listening in Java is accomplished via a ServerSocket. You aren't using one. Instead you're using Sockets at both ends. So what you have is two clients and no server. No communication is possible between two TCP clients.