Android ipv4 使用组播在局域网下通讯。

本文主要功能是多台Android设备使用组播在局域网下通讯。本文为在IPv4下的。

一、获取组播地址并且joinGroup：

private InetAddress broadcastAddress; private void initCast() { try { broadcastAddress = IpUtils.getBroadcastAddress(); multicastSocket = new MulticastSocket(7878); multicastSocket.joinGroup(broadcastAddress); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }

 

public static InetAddress getBroadcastAddress() throws IOException { // 获取本地所有网络接口 Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces(); while (interfaces.hasMoreElements()) { NetworkInterface networkInterface = interfaces.nextElement(); if (networkInterface.isLoopback() || !networkInterface.isUp()) { continue; } // getInterfaceAddresses()方法返回绑定到该网络接口的所有 IP 的集合 for (InterfaceAddress interfaceAddress : networkInterface.getInterfaceAddresses()) { InetAddress broadcast = interfaceAddress.getBroadcast(); if (broadcast == null) { continue; } return broadcast; } } return null; }

二、发送与接受数据。

private void receiverData() { new Thread(){ public void run(){ try { byte[] data = new byte[125]; pack = new DatagramPacket(data, data.length); multicastSocket.receive(pack); Log.i(TAG, "receiverData---"+Arrays.toString(data));//show data } catch (Exception e) { e.printStackTrace(); } } }.start(); } private void sendData() { new Thread(){ public void run(){ try { byte[] data = "来了，老弟！".getBytes(); DatagramPacket pack = new DatagramPacket(data, data.length, broadcastAddress,7878); multicastSocket.send(pack); } catch (Exception e) { e.printStackTrace(); } } }.start(); }

三、以上代码在多台Android设备连接同一WiFi下可行，但是有些手机可以开热点的同时连接WiFi（比如一些小米手机），这个时候可能就会出现问题。解决办法：发现同时开热点连接WiFi会有两个组播地址、两个IP地址；只需要加入组的时候将两个组播地址都加入组，并且发送数据的时候两个组都发送。看代码：

private List<InetAddress> listAddress; private void initCastT() { try { listAddress = IpUtils.getListBroadcastAddress(); multicastSocket = new MulticastSocket(7878); try {//此处单独try是应为这里会抛异常，防止导致下面代码运行不到。 multicastSocket.joinGroup(listAddress.get(0)); } catch (Exception e) { // TODO: handle exception } if (listAddress.size() == 2) { try { multicastSocket.joinGroup(listAddress.get(1)); } catch (Exception e) { // TODO: handle exception } } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void sendDataT() { new Thread(){ public void run(){ try { byte[] data = "来了，老弟！".getBytes(); DatagramPacket pack = new DatagramPacket(data, data.length, listAddress.get(0),7878); multicastSocket.send(pack); if (listAddress.size() == 2) { DatagramPacket pack1 = new DatagramPacket(data, data.length, listAddress.get(1),7878); multicastSocket.send(pack); } } catch (Exception e) { e.printStackTrace(); } } }.start(); } public static List<InetAddress> getListBroadcastAddress()throws IOException { // 获取本地所有网络接口 List<InetAddress> addList = new ArrayList<InetAddress>(); Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces(); while (interfaces.hasMoreElements()) { NetworkInterface networkInterface = interfaces.nextElement(); if (networkInterface.isLoopback() || !networkInterface.isUp()) { continue; } // getInterfaceAddresses()方法返回绑定到该网络接口的所有 IP 的集合 for (InterfaceAddress interfaceAddress : networkInterface.getInterfaceAddresses()) { InetAddress broadcast = interfaceAddress.getBroadcast(); if (broadcast == null) { continue; } addList.add(broadcast); } } return addList; } private void receiverData() { new Thread(){ public void run(){ try { while(true){ byte[] data = new byte[125]; pack = new DatagramPacket(data, data.length); multicastSocket.receive(pack); Log.i(TAG, "receiverData---"+Arrays.toString(data));// show receiver data } } catch (Exception e) { e.printStackTrace(); } } }.start(); }

 

最后，代码仅供大家参考，如有错误请帮忙指出，谢谢！