gistfile1.java

public class DiscoveryThread implements Runnable {
	private static String TAG = "DiscoveryThread";
	private DatagramSocket c;
	pirvate static Context mContext;
	private static int PORT = 5549;
	
	@Override
	public void run() {
		byte[] bytes = null;
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		DataOutputStream daos = new DataOutputStream(baos);
		try {
			//依照文件好像不應該照這樣寫?XD
			daos.write(0);
			daos.write(2);
			daos.writeShort(0);
			daos.writeInt(5549);
			daos.writeUTF("AV2000");
			daos.writeInt(0);
			daos.close();
			//total byte size 20
			bytes = baos.toByteArray();

			Log.d(TAG, bytes.length+"");
		} catch (IOException e1) {
			e1.printStackTrace();
		}
		// Find the server using UDP broadcast
		try {
			// Open a port to send the package
			c = new DatagramSocket();
			c.setBroadcast(true);

			// Broadcast the message over all the network interfaces
			Enumeration interfaces = NetworkInterface.getNetworkInterfaces();
			while (interfaces.hasMoreElements()) {
				NetworkInterface networkInterface = (NetworkInterface) interfaces
						.nextElement();

				if (networkInterface.isLoopback() || !networkInterface.isUp()) {
					continue; // Don't broadcast to the loopback interface
				}

				for (InterfaceAddress interfaceAddress : networkInterface
						.getInterfaceAddresses()) {
					InetAddress broadcast = interfaceAddress.getBroadcast();
					if (broadcast == null) {
						continue;
					}

					// Send the broadcast package!
					try {
						DatagramPacket sendPacket = new DatagramPacket(bytes, bytes.length, broadcast, PORT);
						c.send(sendPacket);
					} catch (Exception e) {
					}

					Log.d(TAG,
							getClass().getName()
									+ "Request packet sent to: /"
									+ broadcast.getHostAddress()
									+ "; Interface: "
									+ networkInterface.getDisplayName());
				}
			}

			Log.d(TAG,
					getClass().getName()
							+ "Waiting for a reply!");

			// Wait for a response
			byte[] recvBuf = new byte[1024];
			DatagramPacket receivePacket = new DatagramPacket(recvBuf,
					recvBuf.length);
			c.receive(receivePacket);

			// Have a response
			Log.d(TAG, getClass().getName()
					+ "Broadcast response from: "
					+ receivePacket.getAddress().getHostAddress());

			// Check if the message is correct
			String message = new String(receivePacket.getData()).trim();
			if (message.equals("DISCOVER_FUIFSERVER_RESPONSE")) {
				// DO SOMETHING...
			}

			// Close the port!
			c.close();
		} catch (IOException ex) {

		}
	}

	public static DiscoveryThread getInstance(Context c) {
		mContext = c;
		return DiscoveryThreadHolder.INSTANCE;

	}

	private static class DiscoveryThreadHolder {

		private static final DiscoveryThread INSTANCE = new DiscoveryThread();
	}


}