Homework2

assignments/src/MV3500Cohort2024JulySeptember/homework2/Schnitzler/README.md

+# Schnitzler Homework 2
+
+***
+
+## Description
+Modification of TcpExample3 and adding some code to implement a chat room with multiple clients.
+
+The 'SchnitzlerServer' class sets up a server that listens for incoming client connections on port 2317. When a client connects, the server creates a new handler thread for managing communication with that client. Each client's messages are broadcast to all other connected clients.
+
+The 'SchnitzlerClient' class connects to a server running on localhost at port 2317. It sends user input from the console to the server and displays messages received from the server.
\ No newline at end of file

assignments/src/MV3500Cohort2024JulySeptember/homework2/Schnitzler/SchnitzlerClient.java

+package MV3500Cohort2024JulySeptember.homework2.Schnitzler;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.Socket;
+import java.util.Scanner;
+
+/**
+ *
+ * @author simonschnitzler
+ */
+public class SchnitzlerClient {
+    public final static String LOCALHOST = "0:0:0:0:0:0:0:1"; //Local host
+
+    /**
+     * @param args the command line arguments
+     * @throws java.lang.Exception
+     */
+    public static void main(String[] args) throws Exception {
+        Socket socket = new Socket(LOCALHOST, 2317);
+
+        new Thread(new Reader(socket)).start();
+
+        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
+        Scanner scanner = new Scanner(System.in);
+        while (scanner.hasNextLine()) {
+            out.println(scanner.nextLine());
+        }
+    }
+
+    private static class Reader implements Runnable {
+        private BufferedReader in;
+
+        public Reader(Socket socket) throws IOException {
+            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+        }
+
+        @Override
+        public void run() {
+            try {
+                String message;
+                while ((message = in.readLine()) != null) {
+                    System.out.println(message);
+                }
+            } catch (IOException e) {
+                System.out.println("Error reading from server: " + e);
+            }
+        }
+    }
+    
+}

assignments/src/MV3500Cohort2024JulySeptember/homework2/Schnitzler/SchnitzlerServer.java

+package MV3500Cohort2024JulySeptember.homework2.Schnitzler;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.io.PrintWriter;
+import java.net.InetAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ *
+ * @author simonschnitzler
+ */
+public class SchnitzlerServer {
+    // the set clientWriters contains form all sockets the active PrintStream  
+    private static Set<PrintWriter> clientWriters = new HashSet<>();
+
+    /**
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        System.out.println(SchnitzlerServer.class.getName() + " has started..."); // it helps debugging to put this on console first
+        try (ServerSocket listener = new ServerSocket(2317)) {            
+            while (true) {
+                Handler handler = new Handler(listener.accept()); // create a new thread writing and reading to and from the new socket
+                OutputStream os = handler.socket.getOutputStream();
+                PrintStream ps = new PrintStream(os);
+                
+                InetAddress remoteAddress = handler.socket.getInetAddress();
+                int remotePort = handler.socket.getPort();
+                String message = remoteAddress.getHostName() + "=" + remoteAddress.getHostAddress() + ", " + remotePort + " has connected to the server.";
+                System.out.println(message);
+                ps.println("Welcome " + remoteAddress.getHostName() + "=" + remoteAddress.getHostAddress() + ", " + remotePort + " to the group chat!");
+                for (PrintWriter writer : clientWriters) {
+                        writer.println(message);
+                    }
+                ps.flush();
+                handler.start();               
+            }
+        }catch (IOException e) {
+            System.err.println("Problem with " + SchnitzlerServer.class.getName() + " 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!");
+            }
+        }
+            
+    }
+    
+    private static class Handler extends Thread {
+        public final Socket socket;
+        private PrintWriter out;
+        private BufferedReader in;
+
+        public Handler(Socket socket) {
+            this.socket = socket;
+        }
+
+        @Override
+        public void run() {
+            try {
+                in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+                out = new PrintWriter(socket.getOutputStream(), true);
+
+                synchronized (clientWriters) {
+                    clientWriters.add(out);
+                }
+
+                String message;
+                while ((message = in.readLine()) != null) {
+                    String outputMessage = socket.getInetAddress().getHostName() + "=" + socket.getInetAddress().getHostAddress() + ", " + socket.getPort()+ ": " + message;
+                    System.out.println(outputMessage);
+                    for (PrintWriter writer : clientWriters) {
+                        writer.println(outputMessage);
+                    }
+                }
+            } catch (IOException e) {
+                System.out.println("Error handling client: " + e);
+            } finally {
+                try {
+                    socket.close();
+                } catch (IOException e) {
+                    System.out.println("Couldn't close a socket, what's going on?");
+                }
+
+                synchronized (clientWriters) {
+                    clientWriters.remove(out);
+                }
+            }
+        }
+    }
+    
+}

assignments/src/MV3500Cohort2024JulySeptember/homework2/Schnitzler/package-info.java

+/**
+ * TCP Unicast homework assignments supporting the NPS MOVES MV3500 Networked Graphics course.
+ * 
+ * @see <a href="https://gitlab.nps.edu/Savage/NetworkedGraphicsMV3500/-/tree/master/assignments" target="_blank">networkedGraphicsMV3500 assignments</a>
+ * @see java.lang.Package
+ * @see <a href="https://stackoverflow.com/questions/22095487/why-is-package-info-java-useful" target="_blank">StackOverflow: why-is-package-info-java-useful</a>
+ * @see <a href="https://stackoverflow.com/questions/624422/how-do-i-document-packages-in-java" target="_blank">StackOverflow: how-do-i-document-packages-in-java</a>
+ */
+
+package MV3500Cohort2024JulySeptember.homework2.Schnitzler;