package udp;

 import java.io.IOException;

 import java.net.DatagramPacket;

 import java.net.InetAddress;

 import java.net.MulticastSocket;

 import java.util.Scanner;

 public class BroadcastSocket implements Runnable{

     private static final String BROADCAST_IP = "230.0.0.1";

     public static final int BROADCAST_PORT = 3000;

     private static final int DATA_LEN = 4096;

     private MulticastSocket socket = null;

     private InetAddress broadcastAddress = null;

     //用来接收键盘输入

     private Scanner scan = null;

     //用来接收网络字节

     byte[] inBuff = new byte[DATA_LEN];

     //用将inBuff封装进DatagramPacket

     private DatagramPacket inPacket = new DatagramPacket(inBuff, inBuff.length);

     //封装发送数据的DatagramPacket

     private DatagramPacket outPacket = null;

     public void init() throws IOException {

         try {

             Scanner scan = new Scanner(System.in);

             socket = new MulticastSocket(BROADCAST_PORT);

             broadcastAddress = InetAddress.getByName(BROADCAST_IP);

             socket.joinGroup(broadcastAddress);

             //设置本是否阻止MulticastSocket会发送给自身, true表示阻止

             socket.setLoopbackMode(false);

             //初始化outPacket

             outPacket = new DatagramPacket(new byte[0], 0 , broadcastAddress, BROADCAST_PORT);

             new Thread(this).start();

             //读取键盘输入

             while (scan.hasNextLine()) {

                 //需要先将键盘输入转为byte字节才能设置DatagramPacket的值

                 byte[] buff = scan.nextLine().getBytes();

                 outPacket.setData(buff);

                 socket.send(outPacket);

             }

         } finally {

             socket.close();

         }

     }

     @Override

     public void run() {

         try {

             while (true) {

                 socket.receive(inPacket);

                 System.out.println("聊天信息："+new String(inBuff, 0, inPacket.getLength()));

             }

         } //捕获异常

         catch (IOException ex) {

             ex.printStackTrace();

             try {

                 if (socket != null) {

                     socket.leaveGroup(broadcastAddress);

                     socket.close();

                 }

                 System.exit(1);

             } catch (IOException e) {

                 e.printStackTrace();

             }

         }

     }

     public static void main(String[] args) throws IOException {

         new BroadcastSocket().init();

     }

 }