MulticastDemo.java

package com.example.getlocalinfo;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.util.ArrayList;
import java.util.List;

import xlwireless.deviceutility.XLWirelessUtility;
import xlwireless.tools.XLWirelessLog;
import android.content.Context;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.net.wifi.WifiManager.MulticastLock;
import android.os.AsyncTask;


/// 测试Android多设备之间的组播程序
class MulticastDemo {
	

	// / 测试Android多设备之间的组播程序之初始化与反初始化。
	private MulticastLock multicastLock = null;

	public void init(Context c) {
		// Android的Wifi，默认情况下是不接受组播的，调用MulticastLock对象的acquire方法，获取到组播锁。
		WifiManager wifiManager = (WifiManager) c.getSystemService(Context.WIFI_SERVICE);
		multicastLock = wifiManager.createMulticastLock("multicast.test");
		multicastLock.acquire();
		WifiInfo wifiInfo = wifiManager.getConnectionInfo();
		if (wifiInfo != null) {
			XLWirelessLog.d(TAG, "getBSSID:" + wifiInfo.getBSSID());
		}
		
	}

	public void uninit() {
		if (null != multicastLock) {
			multicastLock.release();
			multicastLock = null;
		}
	}
	
	private static final String TAG = "MulticastDemo";
	private static final int MULTICAST_PORT = 5111;
	private static final String GROUP_IP = "239.0.0.10";//224.5.0.7
	private static class WrapAsyncTask extends AsyncTask<Void, Void, Void> {
		@Override
		protected Void doInBackground(Void... arg0) {
			// TODO Auto-generated method stub
			try {
				XLWirelessLog.d(TAG, "findAroundStationIpAddress");
				findAroundStationIpAddress();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return null;
		}
	}
	
	public static void asyncTaskFindAroundStation() {
		new WrapAsyncTask().execute();
	}
	public static List<String> findAroundStationIpAddress() throws IOException {
		String ip = null;
		MulticastSocket multicastSocket = new MulticastSocket(MULTICAST_PORT);
		multicastSocket.setLoopbackMode(true);
		//multicastSocket.setSoTimeout(5000);
		//multicastSocket.setSoTimeout(10 * 1000);//
		InetAddress group = InetAddress.getByName(GROUP_IP);
		multicastSocket.joinGroup(group);
		final byte[] sendData = XLWirelessUtility.getLocalIpAddress().getBytes();
		XLWirelessLog.d(TAG, "sendData: " + new String(sendData));
		DatagramPacket packet = new DatagramPacket(sendData, sendData.length,
				group, MULTICAST_PORT);
		ArrayList<String> ipAddressList = new ArrayList<String>();
		for (;;) {
			multicastSocket.send(packet);
			XLWirelessLog.d(TAG, ">>>send packet ok");
			byte[] receiveData = new byte[256];
			packet = new DatagramPacket(receiveData, receiveData.length);
			XLWirelessLog.d(TAG, "0 receive packet getLength: " + packet.getLength());
			multicastSocket.receive(packet);
			XLWirelessLog.d(TAG, "1 receive packet getLength: " + packet.getLength());			
			String packetIpAddress = packet.getAddress().toString();
			XLWirelessLog.d(TAG, "packet ip address: " + packetIpAddress);
			packetIpAddress = packetIpAddress.substring(1, packetIpAddress.length());

			StringBuilder packetContent = new StringBuilder();
			for (int i = 0; i < receiveData.length; i++) {
				if (receiveData[i] == 0) {
					break;
				}
				packetContent.append((char) receiveData[i]);
			}
			XLWirelessLog.d(TAG, "packet content is:" + packetContent);
			ip = packetContent.toString();
			if (ip.equals(packetIpAddress)) {
				XLWirelessLog.d(TAG, "find station's ip address: " + ip);
				ipAddressList.add(ip);
			} else {
				XLWirelessLog.d(TAG, "not find station's ip address, continue …");
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					XLWirelessLog.e(TAG, "InterruptedException e" + e);
					break;
				}
			}
		}
		return ipAddressList;
	}
}