SimpleServer:

import java.net.*;

import java.io.*;

public class SimpleServer {

   public final static int myPort=20; // 使用port 20

   public static void main(String args[]) {

      //ServerSocket ss; 

      //Socket sc;

      PrintWriter op;

      try {

      ServerSocket ss = new ServerSocket(myPort);

       while (true) {

      Socket sc = ss.accept(); // 等待建立連線

op = new PrintWriter(sc.getOutputStream());

 op.println("Hi! There!");

  op.flush(); // 很重要, 不要漏掉

      sc.close();

      //break; 

       }

      }

       catch (IOException e) {

  System.err.println(e);

  }

      System.out.println("end");

/*

 try {

    ss = new ServerSocket(myPort);

    try {

      while (true) {

  sc = ss.accept(); // 等待建立連線

  op = new PrintWriter(sc.getOutputStream());

  op.println("Hi! There!");

  op.flush(); // 很重要, 不要漏掉

  sc.close();

  }

    }

    catch (IOException e) {

  ss.close();

  System.err.println(e);

  }

 }

 catch (IOException e) {

  System.err.println(e);

  }

*/

}

}

MyClient:

import java.net.*;

import java.io.*;

public class MyClient {

  public static final int SERVICE_PORT = 20;

  public static void main(String args[]) {

    // Check for hostname parameter

    if (args.length != 1) {

      System.out.println ("Syntax - DaytimeClient host");

      return;

    }

    // Get the hostname of server

    String hostname = args[0];

    try {

      // Get a socket to the daytime service

      Socket daytime = new Socket (hostname, SERVICE_PORT);

      System.out.println ("Connection established");

      // Set the socket option just in case server stalls

      daytime.setSoTimeout ( 2000 );

      // Read from the server

      BufferedReader reader = new BufferedReader (

      new InputStreamReader(daytime.getInputStream()));

      System.out.println ("Results : " + reader.readLine());

      // Close the connection

      daytime.close();

    } catch (IOException ioe) {

      System.err.println ("Error " + ioe);

    }

  }

}