chat.java

chat.java

@@ -0,0 +1,84 @@
+import java.io.*;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Consumer;
+
+public class chat {
+    private ServerSocket serverSocket; // initialized in ctor
+    private Map<String, Consumer<String>> members = new HashMap<>();
+
+    public static void main(String[] args) {
+        try {
+            new chat().acceptloop();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public chat() throws IOException {
+        this.serverSocket = new ServerSocket(5999);
+    }
+
+    private void acceptloop() throws IOException {
+        while (true) {
+            Socket c = serverSocket.accept();
+            new Thread(new connection(this, c)).start();
+        }
+    }
+
+    public synchronized void connect(String user, Consumer<String> callback) {
+        announce(user + " arrived");
+        members.put(user, callback);
+    }
+
+    public synchronized void disconnect(String user) {
+        members.remove(user);
+        announce(user + " left");
+    }
+
+    public synchronized void speak(String user, String text) {
+        announce(user + " says '" + text + "'");
+    }
+
+    private void announce(String s) {
+        for (Map.Entry<String, Consumer<String>> e : members.entrySet()) {
+            try { e.getValue().accept(s); }
+            catch (Exception ex) { disconnect(e.getKey()); }
+        }
+    }
+
+    private static class connection implements Runnable {
+        private chat room;
+        private Socket c;
+        private static int userCount = 0;
+        private String user = "user" + (userCount++);
+
+        public connection(chat room, Socket c) {
+            this.room = room;
+            this.c = c;
+        }
+
+        @Override
+        public void run() {
+            try {
+                BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
+                PrintWriter out = new PrintWriter(new OutputStreamWriter(c.getOutputStream()));
+                room.connect(user, (String s) -> {
+                    out.println(s);
+                    out.flush();
+                });
+                while (true) {
+                    String line = in.readLine();
+                    if (line == null) break;
+                    room.speak(user, line);
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+            } finally {
+                room.disconnect(user);
+            }
+        }
+    }
+}