import java.net.*;
import java.io.*;

public class tcpServer {

    public static void main(String args[]) {
	int port;        //缺省為1500
	ServerSocket server_socket;
	BufferedReader input;

	try {
	    port = Integer.parseInt(args[0]);
	}catch (Exception e) {
	    System.out.println("port = 1500 (default)");
	    port = 1500;
	}

	try {
	    server_socket = new ServerSocket(port);
	    System.out.println("tcpServer waiting for client on port " +
			       server_socket.getLocalPort());

	    //不停的循環，用于接受客戶端的請求
           int count=0;
	    while(true) {
		Socket socket = server_socket.accept();
                count++;
               new tcpServerThread(socket,count).start();
		System.out.println("New client accepted " +socket.getInetAddress()+ ":" + socket.getPort());
            }
  	}catch (Exception e) {
	    System.out.println(e);
	}
    }
}
class tcpServerThread extends Thread{
    private Socket tcpSocket;
    private   int intNumber;
    public tcpServerThread(Socket socket,int count){
        tcpSocket=socket;
        intNumber=count;
    }
    public void run(){
        try{
             BufferedReader inReader=new BufferedReader(new InputStreamReader(tcpSocket.getInputStream() ));
             PrintWriter outWriter=new PrintWriter(tcpSocket.getOutputStream(),true);

             outWriter.println("Welcome to tcp echo server! your account number is "+intNumber+".please enter EXIT if you want to exit");

             String in="";
             in=inReader.readLine();
             while(!in.trim().equals("EXIT")){
                 outWriter.println("Echo ("+intNumber+"):"+in);
                 in=inReader.readLine();
             }
             outWriter.println("BYE client ("+intNumber+")");
             tcpSocket.close();
             System.out.println("client ("+intNumber+") closed");
        }catch(Exception e){
            System.out.println(e);
        }
    }
}