올해는 머신러닝이다.

ChatClientByConsole.java

public class ChatClientByConsole
{

 static int port = 0;
 static String host = "";
 public ChatClientByConsole(String host,int port)
 {
  this.port = port;
  this.host = host;
  

 }
 public static void main(String[] args)
 {
  new ChatClientByConsole("127.0.0.1",10001);

  Socket sock = null;;
  PrintWriter pw=null;
  BufferedReader br=null;
  BufferedReader br2=null;
  InputStream in;
  OutputStream out;

  try
  {
   sock = new Socket(host,port);
   br = new BufferedReader(new InputStreamReader(System.in));
   in = sock.getInputStream();
   out = sock.getOutputStream();
   pw = new PrintWriter(new OutputStreamWriter(out));
   br2 = new BufferedReader(new InputStreamReader(in));
   
   pw.println(args[0]);
   pw.flush();
   
   String line= null;
   
   //입력쓰레드 생성
   InputThread it = new InputThread(sock,br2);
   it.start();

   while((line=br.readLine())!=null)
   {
    //System.out.println(args[0]+":"+line);
    pw.println(line);
    pw.flush();
   }

   
  }
  catch (SocketException sqe)
  {
   System.out.println("서버와 연결이 안됨");
  }
  catch(Exception ex)
  {
   ex.printStackTrace();
  }
  finally
  {
   try
   {
    if(pw!=null)
     pw.close(); 
    if(br2!=null)
     br2.close(); 
    //if(br2!=null)
    // br2.close();
    if(sock!=null)
     sock.close(); 
   }
   catch (Exception ex)
   {
   }
   
  }
  //키보드로 부터 입력받는다.
  //입력받은 걸 inputStream으로 바꾼다.
  //그런다음

 }
}

class InputThread extends Thread
{
 Socket sock = null;
 BufferedReader br = null;
 PrintWriter pw = null;
 InputStream in = null;
 OutputStream out = null;

 public InputThread(Socket sock,BufferedReader br)
 {
  this.sock = sock;
  this.br = br;
 }

 public void run()
 {
  try
  {
   in=sock.getInputStream();
   out=sock.getOutputStream();

   //br = new BufferedReader(new InputStreamReader(in));
   //pw = new PrintWriter(new OutputStreamWriter(out));
   
   String line = null;

   while( (line=br.readLine()) != null)
   {
    System.out.println(line);
    
   }
  }
  catch (Exception ex)
  {
   ex.printStackTrace();
  }
  finally
  {
   try
   {
    if(pw!=null)
     pw.close(); 
    if(br!=null)
     br.close();
    //if(br2!=null)
    // br2.close();
    if(sock!=null)
     sock.close(); 
   }
   catch (Exception ex)
   {
   }
   
  }
  
 }
}

MultiChatServer.java

public class MultiChatServer
{

 public static void main(String[] args)
 {
  try
  {
   ServerSocket serverSoc = new ServerSocket(10001);
   System.out.println("접속을 기다립니다.");
   HashMap hm = new HashMap();
   while(true)
   {
    Socket sock = serverSoc.accept();
    ChatThread chatthread = new ChatThread(sock,hm);
    chatthread.start();
   }
  }
  catch (Exception ex)
  {
   System.out.println(ex);
  }
  System.out.println("Hello World!");
 }
}

class ChatThread extends Thread
{
 private Socket socket;
 private String id;
 private BufferedReader br;
 private PrintWriter pw;
 private HashMap hm;
 private boolean initFlag = false;
 public ChatThread(Socket socket,HashMap hm)
 {
  this.socket = socket;
  this.hm = hm;
 
  try
  {
   pw = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
   br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
   //System.out.println("11111");
   id=br.readLine();
   //System.out.println("22222");
   broadcast(id +"님이 접속했습니다.");
   System.out.println("접속한 사용자의 아이디는 "+ id +"입니다.");
   
   synchronized(hm)
   {
    hm.put(this.id,pw);
   }
   
   initFlag = true;
  }
  catch (Exception ex)
  {
   //System.out.println("111111111");
   ex.printStackTrace();
  }
 }
 public void run()
 {
  try
  {
   String line = null;
   System.out.println("1111111111");
   while((line = br.readLine()) != null)
   {
    broadcast(id + ":" +line);
   }
   System.out.println("22222222222");
  }
  catch (Exception ex)
  {
   //System.out.println("2222222");
   ex.printStackTrace();
  }
  finally
  {
   synchronized(hm)
   {
    hm.remove(id);
   }
   try
   {
    if(socket!=null)
     socket.close(); 
   }
   catch (Exception ex)
   {
   }
  }

 }
 public void broadcast(String msg)
 {
  synchronized(hm)
  {
   Collection col = hm.values();
   Iterator iter = col.iterator();
   while(iter.hasNext())
   {
    PrintWriter pw = (PrintWriter)iter.next();
    pw.println(msg);
    pw.flush();
   }
  }
 }
}