atmserver.java

Java经典例程 从外国一大学计算机教授出版物下载的代码 经典

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

class ATMServer {

  /* A simple server program  by J M Bishop December 1996
   * =======================
   *                          Java 1.1 revised January 1998
   *                          Java 1.2 B Worrall August 2000
   * Allows multiple simultaneous connections.
   * Illustrates sockets and networking.
   */

  static final String magicPIN = "5678";
  static int          port = 8190;
  InetAddress         serverAddress = null;
  private boolean     done = false;

  public static void main(String[] args) {
   // Set up the port address from the command line,
   // or default to 8190
    if (args.length > 0)
       port =Integer.parseInt(args[0]);
       new ATMServer (port);
  }


  ATMServer (int port) {

     try {
       serverAddress = InetAddress.getLocalHost();
     } catch (UnknownHostException e) {}

   // Initial printing on Server side only
   // using System.out

     System.out.println("******  SAVANNA BANK ********");
     System.out.println("Simulate an ATM session by "
           + "telnetting in to ");
     System.out.println(serverAddress.getHostName() +
           " on port "+port);
     System.out.println("from any number of different computers or");
     System.out.println("from different active Windows.");

   // Set up the server socket
      try {
        ServerSocket listener = new ServerSocket(port);

        int c = 0;
        while (!done) {

          // This is where the program waits for new clients
          Socket client = listener.accept( );
          c ++;
          System.out.println("Card inserted on " +
                client.getInetAddress().getHostName());
          System.out.println("Starting a new client, numbered "
                +c);
          new handler(client, c).start();
        }
        listener.close();
      }
      catch (IOException e) {
        System.out.println("Port "+port+
          " may be busy. Try another.");
      }
   }

  void closeDown () {
    done = true;
  }

class handler extends Thread {

   private Socket toClient;
   private int id;

     handler(Socket s, int i) {
     // Remember the client socket number and client id number
       toClient = s;
       id = i;
     }

     public void run() {

     try {
       Stream conin = new Stream (toClient.getInputStream());
       PrintWriter conout = new
         PrintWriter(toClient.getOutputStream(),true);

       conout.println( "Welcome to Savanna Bank");
       for (int tries = 0; tries < 3; tries++) {
         conout.println("Please type in your PIN "+
            "number or type CANCEL");
         String s = conin.readLine();
         System.out.println("Client "+id+":"+s);

         if (s.equals("SHUTDOWN")) closeDown();
         else if (s.equals("CANCEL")) {
           conout.println("Transactions halted. Goodbye.");
           break;
         }

         else if (s.equals(magicPIN)) {
           conout.println("Please start your transactions");
           break;
         }
         else
           conout.println("Incorrect PIN. Try again.");
       }
       System.out.println("Simulation complete. Thanks.");
     }
     catch (IOException e) {System.out.println("IO Error");}
   }
}
}