package chat;
import java.io.*;
import java.net.*;
import java.util.*;
/** Trivial Chat Server to go with our Trivial Chat Client.
*
* WARNING -- this code is believed thread-safe but has NOT been 100% vetted
* by a team of world-class experts for Thread-safeness.
* DO NOT BUILD ANYTHING CRITICAL BASED ON THIS until you have done so.
* See the various books on Threaded Java for design issues.
*
* @author Ian F. Darwin, http://www.darwinsys.com/
* @version $Id: ChatServer.java,v 1.10 2004/03/13 21:56:32 ian Exp $
*/
public class ChatServer {
/** What I call myself in system messages */
protected final static String CHATMASTER_ID = "ChatMaster";
/** What goes between any handle and the message */
protected final static String SEP = ": ";
/** The Server Socket */
protected ServerSocket servSock;
/** The list of my current clients */
protected ArrayList clients;
/** Debugging state */
private static boolean DEBUG = false;
/** Main just constructs a ChatServer, which should never return */
public static void main(String[] argv) {
System.out.println("DarwinSys Chat Server 0.1 starting...");
if (argv.length == 1 && argv[0].equals("-debug"))
DEBUG = true;
ChatServer w = new ChatServer();
w.runServer(); // should never return.
System.out.println("**ERROR* Chat Server 0.1 quitting");
}
/** Construct (and run!) a Chat Service */
ChatServer() {
clients = new ArrayList();
try {
servSock = new ServerSocket(Chat.PORTNUM);
System.out.println("DarwinSys Chat Server Listening on port " +
Chat.PORTNUM);
} catch(IOException e) {
log("IO Exception in ChatServer.<init>" + e);
System.exit(0);
}
}
public void runServer() {
try {
while (true) {
Socket us = servSock.accept();
String hostName = us.getInetAddress().getHostName();
System.out.println("Accepted from " + hostName);
ChatHandler cl = new ChatHandler(us, hostName);
synchronized (clients) {
clients.add(cl);
cl.start();
if (clients.size() == 1)
cl.send(CHATMASTER_ID, "Welcome! you're the first one here");
else {
cl.send(CHATMASTER_ID, "Welcome! you're the latest of " +
clients.size() + " users.");
}
}
}
} catch(IOException e) {
log("IO Exception in runServer: " + e);
System.exit(0);
}
}
protected void log(String s) {
System.out.println(s);
}
/** Inner class to handle one conversation */
protected class ChatHandler extends Thread {
/** The client socket */
protected Socket clientSock;
/** BufferedReader for reading from socket */
protected BufferedReader is;
/** PrintWriter for sending lines on socket */
protected PrintWriter pw;
/** The client's host */
protected String clientIP;
/** String form of user's handle (name) */
protected String login;
/* Construct a Chat Handler */
public ChatHandler(Socket sock, String clnt) throws IOException {
clientSock = sock;
clientIP = clnt;
is = new BufferedReader(
new InputStreamReader(sock.getInputStream()));
pw = new PrintWriter(sock.getOutputStream(), true);
}
/** Each ChatHandler is a Thread, so here's the run() method,
* which handles this conversation.
*/
public void run() {
String line;
try {
while ((line = is.readLine()) != null) {
char c = line.charAt(0);
line = line.substring(1);
switch (c) {
case Chat.CMD_LOGIN:
if (!Chat.isValidLoginName(line)) {
send(CHATMASTER_ID, "LOGIN " + line + " invalid");
log("LOGIN INVALID from " + clientIP);
continue;
}
login = line;
broadcast(CHATMASTER_ID, login +
" joins us, for a total of " +
clients.size() + " users");
break;
case Chat.CMD_MESG:
if (login == null) {
send(CHATMASTER_ID, "please login first");
continue;
}
int where = line.indexOf(Chat.SEPARATOR);
String recip = line.substring(0, where);
String mesg = line.substring(where+1);
log("MESG: " + login + "-->" + recip + ": "+ mesg);
ChatHandler cl = lookup(recip);
if (cl == null)
psend(CHATMASTER_ID, recip + " not logged in.");
else
cl.psend(login, mesg);
break;
case Chat.CMD_QUIT:
broadcast(CHATMASTER_ID,
"Goodbye to " + login + "@" + clientIP);
close();
return; // The end of this ChatHandler
case Chat.CMD_BCAST:
if (login != null)
broadcast(login, line);
else
log("B<L FROM " + clientIP);
break;
default:
log("Unknown cmd " + c + " from " + login + "@" + clientIP);
}
}
} catch (IOException e) {
log("IO Exception: " + e);
} finally {
// the sock ended, so we're done, bye now
System.out.println(login + SEP + "All Done");
synchronized(clients) {
clients.remove(this);
if (clients.size() == 0) {
System.out.println(CHATMASTER_ID + SEP +
"I'm so lonely I could cry...");
} else if (clients.size() == 1) {
ChatHandler last = (ChatHandler)clients.get(0);
last.send(CHATMASTER_ID,
"Hey, you're talking to yourself again");
} else {
broadcast(CHATMASTER_ID,
"There are now " + clients.size() + " users");
}
}
}
}
protected void close() {
if (clientSock == null) {
log("close when not open");
return;
}
try {
clientSock.close();
clientSock = null;
} catch (IOException e) {
log("Failure during close to " + clientIP);
}
}
/** Send one message to this user */
public void send(String sender, String mesg) {
pw.println(sender + SEP + mesg);
}
/** Send a private message */
protected void psend(String sender, String msg) {
send("<*" + sender + "*>", msg);
}
/** Send one message to all users */
public void broadcast(String sender, String mesg) {
System.out.println("Broadcasting " + sender + SEP + mesg);
for (int i=0; i<clients.size(); i++) {
ChatHandler sib = (ChatHandler)clients.get(i);
if (DEBUG)
System.out.println("Sending to " + sib);
sib.send(sender, mesg);
}
if (DEBUG) System.out.println("Done broadcast");
}
protected ChatHandler lookup(String nick) {
synchronized(clients) {
for (int i=0; i<clients.size(); i++) {
ChatHandler cl = (ChatHandler)clients.get(i);
if (cl.login.equals(nick))
return cl;
}
}
return null;
}
/** Present this ChatHandler as a String */
public String toString() {
return "ChatHandler[" + login + "]";
}
}
}
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