chatterserver.java

很有用的课件

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

public class ChatterServer {
  static final int INPORT = 1711;
  private byte[] buf = new byte[1000];
  private DatagramPacket dp = 
    new DatagramPacket(buf, buf.length);
  // Can listen & send on the same socket:
  private DatagramSocket socket;

  public ChatterServer() {
    try {
      socket = new DatagramSocket(INPORT);
      System.out.println("Server started");
      while(true) {
        // Block until a datagram appears:
        socket.receive(dp);
        String rcvd = Dgram.toString(dp) +
          ", from address: " + dp.getAddress() +
          ", port: " + dp.getPort();
        System.out.println(rcvd);
        String echoString = 
          "Echoed: " + rcvd;
        // Extract the address and port from the
        // received datagram to find out where to
        // send it back:
        DatagramPacket echo = 
          Dgram.toDatagram(echoString,
            dp.getAddress(), dp.getPort());
        socket.send(echo);
      }
    } catch(SocketException e) {
      System.err.println("Can't open socket");
      System.exit(1);
    } catch(IOException e) {
      System.err.println("Communication error");
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    new ChatterServer();
  }
}