ブロードキャストアドレスを得る

gistfile1.java

import java.net.InetAddress;
import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Enumeration;

public class BroadcastAddressTest {

	public static void main(String[] args) throws SocketException {
		BroadcastAddressTest client = new BroadcastAddressTest();
		System.out.println(client.getBroadcastAddress().toString());
	}

	public InetAddress getBroadcastAddress() throws SocketException {
		Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
		while (networkInterfaces.hasMoreElements()) {
			NetworkInterface nif = networkInterfaces.nextElement();
			if (nif.isLoopback() || !nif.isUp()) {
			    // ループバックまたは起動してないインタフェースは無視する
				continue;
			}
			List<InterfaceAddress> addresses = nif.getInterfaceAddresses();
			for (InterfaceAddress address : addresses) {
				InetAddress broadcast = address.getBroadcast();
				if (broadcast != null) {
				    // 最初に見つかったブロードキャストアドレスを返す
					return broadcast;
				}
			}
		}
		return null;
	}
}