RmiServer.java

package merrmiserver;

import java.awt.BorderLayout;
import java.awt.Desktop;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.MalformedURLException;
import java.net.NetworkInterface;
import java.net.Socket;
import java.net.SocketException;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.UnknownHostException;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.server.UnicastRemoteObject;
import java.util.Enumeration;

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;

/**3-Piece demo of RMI
 * merrmiserver.RmiServer.java
 * merrmiserver.RmiServerIntf.java
 * merrmiclient.RmiClient.java
 *
 *
 * This has an initial handshake in the reverse direction; client will act as
 * server and server as client to exchange IP for future RMI calls.
 *
 * 1. Start the RmiClient.  This will instantiate a second Server that will stop and
 * wait for a Client connection from the RmiServer's own second Client, which will feed it the
 * RmiServer's IP.
 * 2. Start the RmiServer.  This'll spawn the secondary client to send the IP to the RmiClient,
 * and will then start the Server to wait for that client to connect.
 * 3. Let the RmiClient proceed to connect to the RmiServer on the established port and invoke the remote
 * method laid out in the RmiServerIntf class.
 * @author Meredith
 *
 */
public class RmiServer
    extends UnicastRemoteObject
    implements RmiServerIntf {


    private static JTextArea jta;
    private static JLabel jl1;
    private static JLabel jl2;

    public RmiServer() throws RemoteException {
        super(0);    // required to avoid the 'rmic' step, see below
        JFrame jf = new JFrame();
        jf.setSize(300,300);
        JPanel jp = new JPanel();
        jp.setSize(jf.getSize());
        jf.setLayout(new BorderLayout());
        jf.add(jp,BorderLayout.CENTER);
        jta = new JTextArea();
        jta.setSize(jp.getWidth()-10,jp.getHeight()/2);

        jp.setLayout(new BoxLayout(jp, BoxLayout.Y_AXIS));
        jl1 = new JLabel();
        jl2 = new JLabel();
        jp.add(Box.createVerticalGlue());

        JPanel labelpan = new JPanel();
        labelpan.add(jl1);
        labelpan.add(Box.createHorizontalGlue());
        jp.add(labelpan);

        jp.add(Box.createVerticalStrut(10));

        JPanel labelpan2 = new JPanel();
        labelpan2.add(jl2);
        labelpan2.add(Box.createHorizontalGlue());
        jp.add(labelpan2);

        jp.add(Box.createVerticalStrut(10));
        jp.add(jta);
        jp.add(Box.createVerticalGlue());
        jf.setVisible(true);

        jl1.setText("RMI server started");

        try { //create registry
            LocateRegistry.createRegistry(1099);
            System.out.println("java RMI registry created.");
        } catch (RemoteException e) {
           System.out.println("java RMI registry already exists.");
        }




        // Bind this object instance to the name "RmiServer"
        String ipToServeOn=dafuqIsMyIP();
        System.out.println(String.format("//%s/RmiServer",ipToServeOn));
        try {
            Naming.rebind(String.format("//%s/RmiServer",ipToServeOn), this);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        jl2.setText("PeerServer bound in registry");

        IPSenderClient ipsc = new IPSenderClient(ipToServeOn);
    }


    @Override
    public void browsePage(URL url){
          if(Desktop.isDesktopSupported())
       {
           try {
            Desktop.getDesktop().browse(url.toURI());
        } catch (IOException | URISyntaxException e) {
            e.printStackTrace();
        }
       }
    }

    public static void main(String args[]) throws Exception {

          //Instantiate RmiServer
        RmiServer obj = new RmiServer();


    }

    public static String dafuqIsMyIP()
    {
        String ip=null,ip0=null;
        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            while (interfaces.hasMoreElements()) {
                NetworkInterface iface = interfaces.nextElement();
                // filters out 127.0.0.1 and inactive interfaces
                if (iface.isLoopback() || !iface.isUp())
                    continue;

                Enumeration<InetAddress> addresses = iface.getInetAddresses();
                while(addresses.hasMoreElements()) {
                    InetAddress addr = addresses.nextElement();

                    ip = addr.getHostAddress();
                    if(ip0==null){
                        ip0=ip;
                        if(ip0.contains(":")){ip0="["+ip0+"]"; /*ipv6*/}
                    }
                    jta.append(iface.getDisplayName() + " " + ip+"\n");
                }
            }
        } catch (SocketException e) {
            throw new RuntimeException(e);
        }
        System.out.println(ip0);
        return ip0;
    }

    /*Connects to class that'll have to make the RMI calls to give it the proper IP*/
    class IPSenderClient{
        int portNum;
        public IPSenderClient(String serviceIP){

            portNum=4444;
            try (
                    Socket sSocket = new Socket("localhost", portNum);
                    PrintWriter out = new PrintWriter(sSocket.getOutputStream(), true);
                    BufferedReader in = new BufferedReader(
                        new InputStreamReader(sSocket.getInputStream()));
                ){
                out.println(serviceIP);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }


    }

}