public class ComUtil{ public static final String BROADCAST_IP = "224.2.2.2"; public static final int BOADCAST_PORT = 30000; private static final int DATA_LEN = 100 * 1024; //定義本程序的MulticastSocket實(shí)例 private MulticastSocket socket = null; //定義廣播的IP地址 private InetAddress broadcastAddress = null; //定義接收網(wǎng)絡(luò)數(shù)據(jù)的字符數(shù)組 byte[] inBuff = new byte[DATA_LEN]; //以指定字節(jié)數(shù)組創(chuàng)建準(zhǔn)備接受的DatagramPacket對(duì)象 private DatagramPacket inPacket = new DatagramPacket(inBuff , inBuff.length); //定義一個(gè)用于發(fā)送的DatagramPacket對(duì)象 private DatagramPacket outPacket = null; private Handler handler; //構(gòu)造器，初始化資源 public ComUtil(Handler handler) throws Exception { this.handler = handler; //因?yàn)樵揗ultcastSocket對(duì)象需要接受數(shù)據(jù)，所以有指定端口 socket = new MulticastSocket(BOADCAST_PORT); broadcastAddress = InetAddress.getByName(BROADCAST_IP); //將該socket加入指定的多點(diǎn)廣播地址 socket.joinGroup(broadcastAddress); //設(shè)置本MultcastSocket發(fā)送的數(shù)據(jù)報(bào)將被送到本身 socket.setLoopbackMode(false); //初始化發(fā)送用的DatagramSocket，它包含一個(gè)長度為0的字節(jié)數(shù)組 outPacket = new DatagramPacket(new byte[0] , 0 , broadcastAddress , BOADCAST_PORT); new ReadBroad().start(); } //廣播消息的工具方法 public void broadCast(byte[] msg) { try {  //將msg字符串轉(zhuǎn)換為字節(jié)數(shù)組  byte[] buff = msg;  //設(shè)置發(fā)送用的DatagramPacket里的字節(jié)數(shù)組  outPacket.setData(buff);  //發(fā)送數(shù)據(jù)  socket.send(outPacket); } catch (IOException e) {  e.printStackTrace(); } } //持續(xù)讀取MulticastSocket的線程 class ReadBroad extends Thread { public void run() {  while (true)  {  try  {   //讀取Socket中的數(shù)據(jù)   socket.receive(inPacket);   Message msg = new Message();   msg.what = 0x123;   msg.obj = inBuff;   handler.sendMessage(msg);  }  catch (IOException e)  {   e.printStackTrace();  }  } } }}

public class MainActivity extends Activity{ private Button button; private ImageView img; private ComUtil comUitl; Handler handler = new Handler() { @Override public void handleMessage(Message msg) {  if (msg.what == 0x123)  {  byte[] result = (byte[]) msg.obj;  img.setImageBitmap(BitmapFactory.decodeByteArray(result , 0 , result.length));  } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main_activity); try {  comUitl = new ComUtil(handler); } catch (Exception e) {  e.printStackTrace(); } button = (Button) findViewById(R.id.send_img_all); img = (ImageView) findViewById(R.id.receiver_img); button.setOnClickListener(new View.OnClickListener() {  @Override  public void onClick(View view)  {  sendData();  } }); } private void sendData() { Bitmap bitmap = BitmapFactory.decodeResource(getResources() , R.drawable.wenqing2); ByteArrayOutputStream byteArray = new ByteArrayOutputStream(); bitmap.compress(Bitmap.CompressFormat.PNG , 100 , byteArray); bitmap.recycle(); final byte[] msg = byteArray.toByteArray(); new Thread() {  @Override  public void run()  {  comUitl.broadCast(msg);  } }.start(); try {  byteArray.close(); } catch (IOException e) {  e.printStackTrace(); } }}