java与网络（IPv4组播）

Posted 2022-09-30

1. 接收组播包

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;

public class MulticastReceiver 

  public static void main(String[] args) 
    InetAddress group = null;
    int port = 0;

    try 
      group = InetAddress.getByName(args[0]);
      port = Integer.parseInt(args[1]);
     catch (Exception e) 
      System.err.println("Usage: multicast_address port");
      System.exit(1);
    

    MulticastSocket ms = null;
    try 
      ms = new MulticastSocket(port);
      ms.joinGroup(group);

      System.out.println("waiting for multicast test data");

      byte[] buffer = new byte[8192];
      while (true) 
        DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
        ms.receive(dp);
        String str = new String(dp.getData(), "UTF-8");
        System.out.println(str);
      
     catch (Exception e) 
      e.printStackTrace();
     finally 
      if (ms != null) 
        try 
          ms.leaveGroup(group);
          ms.close();
         catch (Exception e) 
          e.printStackTrace();
        
      
    
  

2. 发送组播包

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.UnknownHostException;

public class MulticastSender 

  public static void main(String[] args) 
    InetAddress addr = null;
    int port = 0;
    byte ttl = (byte) 1;

    try 
      addr = InetAddress.getByName(args[0]);
      port = Integer.parseInt(args[1]);
      if (args.length > 2) 
        ttl = (byte) Integer.parseInt(args[2]);
      
     catch (Exception e) 
      e.printStackTrace();
      System.err.println("Usage: multicast_address port ttl");
      System.exit(1);
    

    byte[] data = "Heres some multicast test data\\r\\n".getBytes();
    DatagramPacket dp = new DatagramPacket(data, data.length, addr, port);

    //指定组播流输出的接口
    InetAddress eth = null;
    try 
      eth = InetAddress.getByName("192.168.1.102"); //接口上的IP
     catch (UnknownHostException e) 
      e.printStackTrace();
    

    try (MulticastSocket ms = new MulticastSocket()) 
      ms.setInterface(eth);
      ms.setTimeToLive(ttl);
      ms.joinGroup(addr);
      for (int i = 1; i < 100; i++) 
        ms.send(dp);
      
      System.out.println("Multicast test data sending complete.");
     catch (Exception e) 
      e.printStackTrace();