【Java例子程序】指定源组播

淡淡的烟草味﹌ 2024-03-27 16:42 8阅读 0赞

## 概述 ##

因公司业务需要使用到指定源组播。经过一番测试，完成了相关功能的小Demo，废话不多说，直接上代码。

## 开发环境 ##

操作系统：Windows  
开发工具：IntelliJ IDEA  
JDK：OpenJDK 19.0.1

## 运行环境 ##

操作系统：中标麒麟V5U2  
JDK：java-11-openjdk-devel

## 发送端 ##

import java.io.IOException;
    import java.net.*;
    
    public class MulticastSender {
        
        private static void usage() {
        
            System.out.println("Usage: java MulticastSender.java address port text");
        }
    
        public static void main(String[] args) throws IOException, InterruptedException {
        
            String host = "",text = "";
            int port = -1;
            if(args.length < 3) {
        
                usage();
                return ;
            }else{
        
                host = args[0];
                port = Integer.parseInt(args[1]);
            }
    
            String[] parts = host.split("\\.");
            if(parts.length != 4) {
        
                System.out.println("非法地址格式，请重新输入");
                return ;
            }else{
        
                int f = Integer.parseInt(parts[0]);
                if(f < 224 || f > 239) {
        
                    System.out.println("非组播地址格式，请重新输入");
                    return ;
                }
            }
    
            if(port <=0 || port > 65535) {
        
                System.out.println("非法端口数值，请重新输入");
                return ;
            }
    
            text = args[2];
            if(text.isEmpty()) {
        
                System.out.println("请输入需要发送的内容");
                return;
            }
    
            MulticastSocket socket = new MulticastSocket();
            InetSocketAddress isa = new InetSocketAddress(InetAddress.getByName(host), port);
            NetworkInterface ni = NetworkInterface.getByInetAddress(InetAddress.getByName("192.168.1.4"));
            socket.joinGroup(isa, null);
            socket.setTimeToLive(5);
            DatagramPacket dp = new DatagramPacket(text.getBytes(),text.length(), isa);
            while(true) {
        
                System.out.println("Sending Data...");
                socket.send(dp);
                Thread.sleep(1000);
            }
        }
    }

## 接收端 ##

import java.io.IOException;
    import java.net.*;
    import java.nio.ByteBuffer;
    import java.nio.channels.DatagramChannel;
    import java.nio.channels.MembershipKey;
    import java.nio.channels.MulticastChannel;
    
    /**
     * 该程序在Linux平台下测试通过，但是Windows收不到Linux发出的数据
     */
    public class SpecialMulticastReceiver {
        
        private static void usage() {
        
            System.out.println("Usage: java SpecialMulticastReceiver.java address port");
        }
    
        public static void main(String[] args) throws IOException, InterruptedException {
        
            String host = "";
            int port = -1;
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            //byte buffer[] = new byte[1024];
            if(args.length < 2) {
        
                usage();
                return ;
            }else{
        
                host = args[0];
                port = Integer.parseInt(args[1]);
            }
    
            String[] parts = host.split("\\.");
            if(parts.length != 4) {
        
                System.out.println("非法地址格式，请重新输入");
                return ;
            }else{
        
                int f = Integer.parseInt(parts[0]);
                if(f < 224 || f > 239) {
        
                    System.out.println("非组播地址格式，请重新输入");
                    return ;
                }
            }
    
            if(port <=0 || port > 65535) {
        
                System.out.println("非法端口数值，请重新输入");
                return ;
            }
    
            InetSocketAddress isa = new InetSocketAddress(port);
            NetworkInterface ni = NetworkInterface.getByInetAddress(InetAddress.getByName("192.168.1.4"));
            DatagramChannel dc = DatagramChannel.open(StandardProtocolFamily.INET)
                    .setOption(StandardSocketOptions.SO_REUSEADDR, true)
                    .setOption(StandardSocketOptions.IP_MULTICAST_LOOP, false)
                    .bind(isa)
                    .setOption(StandardSocketOptions.IP_MULTICAST_IF, ni);
    
            //添加指定源
            MembershipKey key = dc.join(InetAddress.getByName(host), ni, InetAddress.getByName("192.168.1.4"));
            MembershipKey key1 = dc.join(InetAddress.getByName(host), ni, InetAddress.getByName("192.168.1.5"));
            MulticastChannel mc = key.channel();
            while(true) {
        
                //接收数据
                while((((DatagramChannel)mc).receive(buffer))!= null) {
        
                    buffer.flip();
                    System.out.println("Data: " + new String(buffer.array()));
                    buffer.clear();
                }
            }
        }
    }

## 问题&回答 ##

Q: 接收端的代码在Windows平台死活收不到数据，不知道什么情况。但是在Linux平台则一切正常，有知道的小伙伴，希望解答一下哈。  
A：

Q：在中标麒麟下添加指定源地址，当数量达到10个就会出现添加失败的情况。  
A：修改net.ipv4.igmp\_max\_msf属性，其他linux内核应该也能通用。  
修改代码如下：

echo "net.ipv4.igmp_max_msf=128" >> /etc/sysctl.conf
    sysctl -p

## 参考链接 ##

[【技术】组播技术详解系列——组播基础][Link 1]  
[MulticastChannel (Java SE 11 & JDK 11 )][MulticastChannel _Java SE 11 _ JDK 11]

[Link 1]: http://www.360doc.com/content/21/0805/17/76478479_989653597.shtml
[MulticastChannel _Java SE 11 _ JDK 11]: https://www.runoob.com/manual/jdk11api/java.base/java/nio/channels/MulticastChannel.html