服务器端小程序

本机打开cmd，输入telnet 127.0.0.1 8189，在输入任意字符通讯，输入"BYE"结束。

package ch4Test;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class EchoServer {
    public static void main(String args[]) throws IOException{
        try(ServerSocket s = new ServerSocket(8189)){
            try(Socket incoming = s.accept()){
                InputStream inStream = incoming.getInputStream();
                OutputStream outStream = incoming.getOutputStream();
                
                try(Scanner in = new Scanner(inStream)){
                    PrintWriter out = new PrintWriter(outStream,true /* autoFlush */);
                    out.println("Hello! Enter BYE to exit.");
                    boolean done = false;
                    while(!done&&in.hasNextLine()){
                        String line = in.nextLine();
                        out.println("Echo:"+line);
                        if(line.trim().equals("BYE")) done = true;
                    }
                }catch(Exception e){
                    
                }
            }catch(Exception e){
                e.printStackTrace();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}