udpechoserver.java

利用UDP实现网络聊天室

package udpecho;

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2002</p>
 * <p>Company: </p>
 * @author unascribed
 * @version 1.0
 */
import java.net.*;
import java.io.*;
abstract class UDPServer extends Thread{
  private int bufferSize;
  protected DatagramSocket ds;
  public UDPServer(int port,int bufferSize) throws SocketException{
    this.bufferSize =bufferSize;
    this.ds =new DatagramSocket(port);
  }
  public UDPServer(int port) throws SocketException{
    this(port,8192);
  }
  public void run(){
    byte[] buffer=new byte[bufferSize];
    while (true){
      DatagramPacket incoming=new DatagramPacket(buffer,buffer.length);
      try{
        ds.receive(incoming);
        this.respond(incoming);
      }
      catch (IOException e){
        System.err.println(e);
      }
    }
  }
  public abstract void respond(DatagramPacket request);
}

public class UDPEchoServer extends UDPServer {
  public final static int DEFAULT_PORT=7;
  public UDPEchoServer() throws SocketException{
    super(DEFAULT_PORT);
  }
  public void respond(DatagramPacket packet){
    try{
      DatagramPacket outgoing=new DatagramPacket(packet.getData(),packet.getLength(),packet.getAddress(),packet.getPort());
      ds.send(outgoing);
    }
    catch (IOException e){
      System.err.println(e);
    }
  }
  public static void main(String[] args){
    try{
      UDPEchoServer server=new UDPEchoServer();
      server.start();
    }
    catch (SocketException e){
      System.err.println(e);
    }
  }
}