發送UDP廣播

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class UdpUtil {
 /**
  * UDP發送
  *
  * @param message
  *            廣播的內容
  * @param port
  *            服務器監聽的端口號
  * @param host
  *            PC/服務器端IP地址
  */
 public static void sendMessage(String message, int port, String host) {
  message = (message == null ? "空了" : message);
  DatagramSocket ds = null;
  try {
   ds = new DatagramSocket();
  } catch (SocketException e) {
   e.printStackTrace();
  }
  InetAddress local = null;
  try {
   local = InetAddress.getByName(host);
  } catch (UnknownHostException e) {
   e.printStackTrace();
  }
  int msgLength = message.length();
  byte[] messageByte = message.getBytes();
  DatagramPacket dp = new DatagramPacket(messageByte, msgLength, local, port);
  try {
   ds.send(dp);
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   ds.close();
  }

 }
}