GaribayServer.java

package MV3500Cohort2020JulySeptember.homework2.Garibay;

import java.io.*;
import java.net.*;

/**
 *
 * @author Chris
 */
public class GaribayServer {

    public static void main(String[] args) {
        try {
            
            // ServerSocket waits for a connection from a client. 
            // Notice that it is outside the loop; ServerSocket
            // needs to be made only once.
            System.out.println("TcpExample3Server has started..."); // it helps debugging to put this on console first
            
            ServerSocket serverSocket = new ServerSocket(2317);
            OutputStream os;
            PrintStream ps;
            InetAddress localAddress, remoteAddress;
            
            InputStream is;
            InputStreamReader isr;
            BufferedReader br;
            String clientMessage;
            int localPort, remotePort;

            // Server is up and waiting (i.e. "blocked" or paused)
            // Loop, infinitely, waiting for client connections.
            // Stop the program somewhere else.
            while (true) { 
                
                // block until connected to a client
                try (Socket clientConnection = serverSocket.accept()) {
                    
                    // Now hook everything up (i.e. set up the streams), Java style:
                    os = clientConnection.getOutputStream();
                    ps = new PrintStream(os);
                    ps.println("Count for yourself!"); // this gets sent back to client!
                    
                    // Print some information locally about the Socket connection.
                    // This includes the port and IP numbers on both sides (the socket pair).
                    localAddress = clientConnection.getLocalAddress();
                    remoteAddress = clientConnection.getInetAddress();
                    localPort = clientConnection.getLocalPort();
                    remotePort = clientConnection.getPort();
                    
                    // My socket pair connection looks like this, to localhost:
                    // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54876 ))
                    // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54881 ))
                    
                    // Why is the first IP/port the same, while the second set has different ports?
                    System.out.println("TcpExample3Server socket pair: (( " + localAddress.toString() + ", " + localPort + " ), ( "
                            + remoteAddress.toString() + ", " + remotePort + " ))");
                    
                    // Notice the use of flush() and try w/ resources. Without
                    // the try w/ resources the Socket object may stay open for
                    // a while after the client has stopped needing this
                    // connection. try w/ resources explicitly ends the connection.
                    
                                    // Now hook everything up (i.e. set up the streams), Java style:
                is = clientConnection.getInputStream();
                isr = new InputStreamReader(is);
                br = new BufferedReader(isr);
                

                // Read a single line written by the server. We'd
                // do things a bit differently if there were many lines to be read
                // from the server instead of one only.
                clientMessage = br.readLine();
                System.out.println("==================================================");
                System.out.println("Now we're talking!");
                System.out.println("The message the server sent was: '" + clientMessage + "'");
//                System.out.println("This was the "+ count +" connection.");
                    
              
                    ps.flush();
                    // like it or not, you're outta here!
                }
            }
        } catch (IOException e) {
            System.err.println("Problem with TcpExample3Server networking: " + e);

            // Provide more helpful information to user if exception occurs due to running twice at one time
            if (e instanceof java.net.BindException) {
                System.err.println("*** Be sure to stop any other running instances of programs using this port!");
            }
        }
    }
}