/*** 监听整个组播地址内的群消息*/public static void listenGroupMsg() {MulticastSocket msr = null;try {InetAddress group = InetAddress.getByName(DEFAULT_BROADCASE_IP);msr = new MulticastSocket(DEFAULT_BROADCASE_PORT);msr.joinGroup(group);byte[] buf = new byte[1024];while (true) {DatagramPacket dp = new DatagramPacket(buf, buf.length);msr.receive(dp);GroupMsg groupMsg = getGroupMsg(dp.getData());if (groupMsg != null) {System.out.println(groupMsg.toString());}}} catch (Exception e) {e.printStackTrace();} finally {if (msr != null) {msr.close();}}}private static GroupMsg getGroupMsg(byte[] data) throws Exception {if (!isGroupMsgType(data)) {return null;}//整个消息类似于这种格式//1_lbt6_0#128#080027090471#0#0#96#4001#9:1466349191:vitrual:VB:4194339:晠8q凗梢舔�}J=R�B騪N�h1'r熜�=猙熇YC翝�2�酒f*膭h鋮String mac = getGroupMac(data);String userName = getUserName(data);String pcName = getPcName(data);byte[] encryData = getEncryData(data, getEncryDataLength(data));if (encryData == null) {return null;}byte[] decryData = decrypt(mac, encryData);//从消息体中获取群号和消息内容//QUNMSGMARK#3b199b07_24901708#/:bomb{/font;-16 0 0 0 400 0 0 0 134 0 0 2 32 微软雅黑 8404992;}String msgBody = new String(decryData, DEFAULT_ENCODING);GroupMsg groupMsg = new GroupMsg();groupMsg.setMac(mac);groupMsg.setUserName(userName);groupMsg.setPcName(pcName);groupMsg.setTime(DateUtil.getFormatTime(new Date()));if (msgBody.indexOf("#") > 0 && msgBody.indexOf("_") > 0) {groupMsg.setGroupNum(Long.valueOf(msgBody.substring(msgBody.indexOf("#") + 1, msgBody.indexOf("_")), 16));msgBody = msgBody.substring(msgBody.indexOf("_"));}if (msgBody.lastIndexOf("{") > 0 && msgBody.indexOf("#") > 0) {groupMsg.setMsg(msgBody.substring(msgBody.indexOf("#") + 1, msgBody.lastIndexOf("{")));}return groupMsg;}

 /*** 向指定群，发送群消息** @param groupNum* @param msg* @param userName* @param pcName* @param mac*/public static void sendGroupMsg(long groupNum, String msg, String userName, String pcName, String mac) {try {InetAddress group = InetAddress.getByName(DEFAULT_BROADCASE_IP);MulticastSocket msr = new MulticastSocket(DEFAULT_BROADCASE_PORT);msr.joinGroup(group);byte[] sendData = getSendData(groupNum, msg, userName, pcName, mac);DatagramPacket dp = new DatagramPacket(sendData, sendData.length, group, DEFAULT_BROADCASE_PORT);msr.send(dp);msr.close();} catch (Exception e) {e.printStackTrace();}}private static byte[] getSendData(long groupNum, String msg, String userName, String pcName, String mac) throws Exception {byte[] groupData = String.format("QUNMSGMARK#%s_%d#%s%s", Long.toHexString(groupNum), (System.currentTimeMillis() / 1000), msg, DEFAULT_FONT).getBytes(DEFAULT_ENCODING);byte[] groupEncryptData = encrypt(mac, groupData);byte[] headData = String.format("1_lbt4_0#128#%s#0#0#%d#4000#9:%d:%s:%s:%d:", mac, groupEncryptData.length, (System.currentTimeMillis() / 1000), pcName, userName, MSG_TYPE_GROUP).getBytes(DEFAULT_ENCODING);byte[] fullData = new byte[headData.length + groupEncryptData.length];System.arraycopy(headData, 0, fullData, 0, headData.length);System.arraycopy(groupEncryptData, 0, fullData, headData.length, groupEncryptData.length);return fullData;}

测试结果