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package javaChat;
import java.net.* ;
import java.util.* ;
import java.io.* ;
public class ChatServer
{
// List of all active users in Server
static ArrayList<ClientHandler> userList = new ArrayList<>() ;
/**
* Accepts Client requests to join chat server, and
* creates new thread for each individual client.
*
* @param args
* @throws IOException
*/
public static void main( String[] args ) throws IOException
{
// Register service on port 6789
ServerSocket serverSocket = new ServerSocket( 6789 ) ;
Socket socket = null ;
System.out.println( "\nServer established. Awaiting connections..." ) ;
// Accept client requests
while( true )
{
socket = serverSocket.accept() ;
DataOutputStream dataStreamOut = new DataOutputStream( socket.getOutputStream() ) ;
DataInputStream dataStreamIn = new DataInputStream ( socket.getInputStream() ) ;
System.out.println( "\nClient connection detected, requesting username..." ) ;
String username = dataStreamIn.readUTF() ;
ClientHandler handle = new ClientHandler( socket, username, dataStreamOut, dataStreamIn ) ;
System.out.println( "\nCreating new thread...\n" ) ;
Thread thread = new Thread( handle ) ;
userList.add( handle ) ;
thread.start() ;
}
}
}
// end class ChatClient
// This class manages the actual messages being sent around
@SuppressWarnings( "javadoc" )
class ClientHandler implements Runnable
{
Socket socket ;
String username ;
final DataOutputStream dataStreamOut ;
final DataInputStream dataStreamIn ;
boolean loggedIn ;
private ArrayList<ClientHandler> userList ;
/**
* Constructor
* @param s : client socket
* @param user : client's user-name
* @param dos : data stream to client
* @param dis : data stream from client
*/
public ClientHandler( Socket s, String user,
DataOutputStream dos,
DataInputStream dis )
{
this.username = user ;
this.socket = s ;
this.dataStreamOut = dos ;
this.dataStreamIn = dis ;
this.loggedIn = true ;
}
@Override
public void run()
{
// Note the connection of the new user
String announcement = String.format( "-= User \"%s\" has successfully connected =-\n", this.username ) ;
System.out.println( announcement ) ;
// Distribute announcement to entire server
distributeAll( announcement ) ;
// Message management
String message = "" ;
while( true )
{
// Read incoming messages
try
{
message = this.dataStreamIn.readUTF() ;
}
catch ( IOException x )
{
x.printStackTrace() ;
}
// Check message for user commands, returns TRUE is user quits
if( commands(message, this) )
{
break ;
}
// Print the message server-side
message = String.format( "%s: %s", this.username, message ) ;
System.out.println( message ) ;
// Distribute the message to all users
sendMessage( message ) ;
// end try
}
try
{
this.loggedIn = false ;
this.socket.close() ;
}
catch( IOException x )
{
x.printStackTrace() ;
}
}
// This method manages the usage of user-commands
public boolean commands(String message, ClientHandler user)
{
String[] commands = new String[] {"/help", "/quit", "/userlist"} ;
try {
// Quit command terminates connection, with an announcement
if( message.equals( "/quit" ))
{
String announcement = String.format( "\n-= \"%s\" has disconnected =- \n", user.username ) ;
System.out.println( announcement ) ;
distributeAll( announcement ) ;
return true ;
}
if( message.equals( "/userlist" ) )
{
user.dataStreamOut.writeUTF( "Current list of users in the server: " ) ;
for( ClientHandler users : ChatServer.userList )
{
if( !users.loggedIn )
{
continue ;
}
user.dataStreamOut.writeUTF( users.username ) ;
}
}
if( message.contentEquals( "/help" ) )
{
user.dataStreamOut.writeUTF( "\nAll available commands: " );
for(int i = 0; i < commands.length; i++ )
{
user.dataStreamOut.writeUTF( commands[i] );
}
user.dataStreamOut.writeUTF( "\n" ) ;
}
}
catch( IOException x )
{
System.out.println( x ) ;
}
return false ;
}
// Convenience method to send messages (but not to the user that's sending the message)
private void sendMessage(String message)
{
try
{
for( ClientHandler users : ChatServer.userList )
{
if( !users.loggedIn || users.equals( this ) )
{
continue ;
}
users.dataStreamOut.writeUTF( "> " + message ) ;
}
}
catch ( IOException x )
{
x.printStackTrace() ;
}
}
// Convenience method to distribute messages to all clients (announcements)
private void distributeAll(String message)
{
try
{
for( ClientHandler users : ChatServer.userList )
{
if( !users.loggedIn )
{
continue ;
}
users.dataStreamOut.writeUTF( message ) ;
}
}
catch ( IOException x )
{
x.printStackTrace() ;
}
}
}
// end class ClientHandler
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