java 使用epoll方式实现组播数据接收

在 Java 中，可以使用 NIO（New I/O）框架来实现 epoll 方式的组播数据接收。

以下是一个简单的示例代码：

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.NetworkInterface;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.MembershipKey;
import java.nio.charset.Charset;
import java.util.Enumeration;
import java.util.concurrent.TimeUnit;

public class MulticastReceiver {
    private static final int PORT = 9999;
    private static final String GROUP_ADDRESS = "239.0.0.1";
    private static final String INTERFACE_NAME = "eth0";
    private static final int MAX_PACKET_SIZE = 65536;

    public static void main(String[] args) throws Exception {
        NetworkInterface networkInterface = NetworkInterface.getByName(INTERFACE_NAME);
        InetSocketAddress groupAddress = new InetSocketAddress(InetAddress.getByName(GROUP_ADDRESS), PORT);
        DatagramChannel channel = DatagramChannel.open();
        channel.setOption(java.net.StandardSocketOptions.SO_REUSEADDR, true);
        channel.bind(new InetSocketAddress(PORT));
        MembershipKey key = channel.join(groupAddress.getAddress(), networkInterface);

        ByteBuffer buffer = ByteBuffer.allocate(MAX_PACKET_SIZE);
        while (true) {
            buffer.clear();
            InetSocketAddress senderAddress = (InetSocketAddress) channel.receive(buffer);
            if (senderAddress != null) {
                String message = new String(buffer.array(), 0, buffer.position(), Charset.forName("UTF-8"));
                System.out.println("Received message from " + senderAddress.getHostString() + ": " + message);
            }
            TimeUnit.MILLISECONDS.sleep(100);
        }
    }
}

这个代码使用 DatagramChannel 类来创建一个 UDP 数据报通道，然后绑定端口，并加入一个组播组。最后，通过 receive() 方法接收来自组播组的数据报。