Datagrams 数据报 示例

//Demonstrate Datagrams.
import java.net.*;
class WriteServer{
 public static int serverPort = 666 ;
 public static int clientPort = 999 ;
 public static int buffer_size = 1024 ;
 public static  DatagramSocket ds ;
 public static byte buffer[] = new byte[buffer_size];

 public static void TheServer() throws Exception{
  int pos = 0;
  while(true){
   int c = System.in.read();
   switch(c){
    case -1:
     System.out.println("Server Quits.");
     return;
    case '\r':
     break;
    case '\n':
     ds.send(new DatagramPacket(buffer,pos,InetAddress.getLocalHost(),clientPort));
     pos = 0;
     break;
    default:
     buffer[pos++] = (byte)c;
   }
  }
 }
 public static void TheClient() throws Exception{
  while(true){
   DatagramPacket p = new DatagramPacket (buffer,buffer.length);
   ds.receive(p);
   System.out.println(new String(p.getData(),0,p.getLength()));
  }
 }
 public static void main(String[] args) throws Exception{
  if(args.length == 1){
   ds = new DatagramSocket(serverPort);
   TheServer();
  }else{
   ds = new DatagramSocket(clientPort);
   TheClient();
  }
 }
}