组播的发送与接收问题

[信息] [引用] [回复] 楼 主 BACK TOP 我写了一个组播的发送与接收的程序　，编译和运行都通过了，但不能接收数据，源程序如下： 接收源程序： import java.io.IOException; import java.net.DatagramPacket; import java.net.InetAddress; import java.net.MulticastSocket; import javax.swing.*; public class ReceiveMulPacket implements Runnable{         DatagramPacket pack;         MulticastSocket mulSocket;         InetAddress inetAddress;                  byte msg[]=new byte[5000];                  public ReceiveMulPacket() throws IOException{                                  mulSocket=new MulticastSocket(9875);                 inetAddress=InetAddress.getByName("226.255.8.0");                 mulSocket.joinGroup(inetAddress);                                  new Thread(this).start();         }         public void run() {                 while(true){                         try {                                 System.out.println("before");                                 pack=new DatagramPacket(msg,msg.length,inetAddress,9875);                                 mulSocket.receive(pack);                                 System.out.println("after");                                 String reMsg=new String(pack.getData(),0,pack.getLength());                                 System.out.println(reMsg);                         } catch (IOException e) {                                 e.printStackTrace();                         }                 }                         }         public static void main(String[] args) {                 try {                         new ReceiveMulPacket();                 } catch (IOException e) {                         // TODO Auto-generated catch block                         e.printStackTrace();                 }         } } 发送源程序： import java.io.IOException; import java.net.DatagramPacket; import java.net.InetAddress; import java.net.MulticastSocket; public class SendMsg {          public static void sendMulPacket(String msg) throws IOException{             byte data[]=msg.trim().getBytes();                         MulticastSocket mulSocket=new MulticastSocket(9875);                         InetAddress inetAddress=InetAddress.getByName("226.255.8.0");                         mulSocket.joinGroup(inetAddress);                         DatagramPacket pack=new DatagramPacket(data,data.length,inetAddress,9875);                         mulSocket.send(pack);    }         public static void main(String[] args) {                 try {                         sendMulPacket("upl"+"information");                         System.out.println("sended");                 } catch (IOException e) {                         // TODO Auto-generated catch block                         e.printStackTrace();                 }         } }