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+tcpSocket.getLocalPort());                 in=inReader.readLine();             }             outWriter.println("BYE client ("+intNumber+")");             tcpSocket.close();             System.out.println("client ("+intNumber+") closed");        }catch(Exception e){            System.out.println(e);        }    }}