Hy , We are working on the android multiplayer game via bluetooth. It is a multiplayer LUDO game in which 4 player connect to each other and play the game.
We are stuck in connection with the 3rd and 4th player connection.
private OnMaxConnectionsReachedListener maxConnectionsListener = new OnMaxConnectionsReachedListener() {
public void OnMaxConnectionsReached() {
}
};
private OnIncomingConnectionListener connectedListener = new OnIncomingConnectionListener() {
public void OnIncomingConnection(String device) {
//rivalDevice = device;
if(index < 1000)
{
clients[index] = device;
index++;
Log.d("Khawar", "Khawar"+device);
if(index == 1)
{
//blue.setText(clients[0]);
mConnection.sendMessage(clients[0], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]);
}
else if(index == 2)
{
//blue.setText(clients[0]);
//red.setText(clients[1]);
mConnection.sendMessage(clients[0], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]+"--Ludofyp309509--"+clients[1]);
mConnection.sendMessage(clients[1], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]+"--Ludofyp309509--"+clients[1]);
}
else if(index==3)
{
//blue.setText(clients[0]);
//red.setText(clients[1]);
//yellow.setText(clients[2]);
mConnection.sendMessage(clients[0], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]+"--Ludofyp309509--"+clients[1]+"--Ludofyp309509--"+clients[2]);
mConnection.sendMessage(clients[1], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]+"--Ludofyp309509--"+clients[1]+"--Ludofyp309509--"+clients[2]);
mConnection.sendMessage(clients[2], "ConnectionList--Ludofyp309509--"+server+"--Ludofyp309509--"+clients[0]+"--Ludofyp309509--"+clients[1]+"--Ludofyp309509--"+clients[2]);
}
}
//Toast.makeText(getBaseContext(), "Client found" + device , Toast.LENGTH_LONG).show();
// WindowManager w = getWindowManager();
// Display d = w.getDefaultDisplay();
// int width = d.getWidth();
//int height = d.getHeight();
}
};
private OnConnectionLostListener disconnectedListener = new OnConnectionLostListener() {
public void OnConnectionLost(String device) {
class displayConnectionLostAlert implements Runnable {
public void run() {
Builder connectionLostAlert = new Builder(self);
connectionLostAlert.setTitle("Connection lost");
connectionLostAlert
.setMessage("Your connection with the other player has been lost.");
connectionLostAlert.setPositiveButton("Ok", new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
connectionLostAlert.setCancelable(false);
try {
connectionLostAlert.show();
} catch (BadTokenException e){
Log.v("TAG", "Exception throws here");
}
}
}
self.runOnUiThread(new displayConnectionLostAlert());
}
};
private OnConnectionServiceReadyListener serviceReadyListener = new OnConnectionServiceReadyListener() {
public void OnConnectionServiceReady() {
if (mType == 0) {
mConnection.startServer(1, connectedListener, maxConnectionsListener,
dataReceivedListener, disconnectedListener);
self.setTitle("LudoOverAndroid: " + mConnection.getName() + "-" + mConnection.getAddress());
server = mConnection.getAddress();
green.setText(server);
Log.v("1", server);
// Intent Game = new Intent(self, Board.class);
// .putExtra("TYPE", 1);
// startActivity(Game);
} else {
self.setTitle("LudoOverAndroid: " + mConnection.getName() + "-" + mConnection.getAddress());
Intent serverListIntent = new Intent(self, ServerListActivity.class);
startActivityForResult(serverListIntent, SERVER_LIST_RESULT_CODE);
clients[index] = mConnection.getAddress();
// Intent Game = new Intent(self, Board.class);
// .putExtra("TYPE", 1);
// startActivity(Game);
}
}
};
Above is the sample code where connection are established. But in the Connection Services class we have the following code
public int connect(String srcApp, String device) throws RemoteException {
if (mApp.length() > 0) {
Log.v("a", "connection service->connect->mApp.length");
return Connection.FAILURE;
}
mApp = srcApp;
BluetoothDevice myBtServer = mBtAdapter.getRemoteDevice(device);
BluetoothSocket myBSock = null;
Log.v("a", "Yaah aya hay aik baar nahe bar bar :");
for (int i = 0; i < Connection.MAX_SUPPORTED && myBSock == null; i++) {
for (int j = 0; j < 3 && myBSock == null; j++) {
myBSock = getConnectedSocket(myBtServer, mUuid.get(i));
if (myBSock == null) {
try {
Log.v("a", "connection service->connect->myBSock==NULL thread sleep");
Thread.sleep(200);
} catch (InterruptedException e) {
Log.e(TAG, "InterruptedException in connect", e);
}
}
}
}
if (myBSock == null) {
Log.v("a", "connection service->connect->myBSock==NULLss");
return Connection.FAILURE;
}
mBtSockets.put(device, myBSock);
mBtDeviceAddresses.add(device);
Thread mBtStreamWatcherThread = new Thread(new BtStreamWatcher(device));
mBtStreamWatcherThread.start();
mBtStreamWatcherThreads.put(device, mBtStreamWatcherThread);
return Connection.SUCCESS;
}
The mobile when connect with the 3rd or 4th device it return myBSock==null. But if the codes work right it must return the address of the device and should add mBtDeviceAddresses.add(device); into the server list.
kindly help us to fix the problem.
Thanks in advance
package com.switching.bluetooth;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.UUID;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import com.switching.ServerMainActivity;
/**
* This class does all the work for setting up and managing Bluetooth
* connections with other devices. It has a thread that listens for incoming
* connections, a thread for connecting with a device, and a thread for
* performing data transmissions when connected.
*/
public class BluetoothService {
// Debugging
private static final String TAG = "BluetoothService iBT";
private static final boolean D = true;
// Name for the SDP record when creating server socket
private static final String NAME = "i BT";
// Unique UUID for this application
private static UUID MY_UUID;
// Member fields
private final BluetoothAdapter mAdapter;
private final Handler mHandler;
private AcceptThread mAcceptThread;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
private int mState;
private ArrayList<String> mDeviceAddresses;
private ArrayList<String> mDeviceNames;
private ArrayList<ConnectedThread> mConnThreads;
private ArrayList<BluetoothSocket> mSockets;
/**
* A bluetooth piconet can support up to 7 connections. This array holds 7
* unique UUIDs. When attempting to make a connection, the UUID on the
* client must match one that the server is listening for. When accepting
* incoming connections server listens for all 7 UUIDs. When trying to form
* an outgoing connection, the client tries each UUID one at a time.
*/
private ArrayList<UUID> mUuids;
// Constants that indicate the current connection state
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_LISTEN = 1; // now listening for incoming
// connections
public static final int STATE_CONNECTING = 2; // now initiating an outgoing
// connection
public static final int STATE_CONNECTED = 3; // now connected to a remote
// device
/**
* Constructor. Prepares a new BluetoothChat session.
*
* @param context
* The UI Activity Context
* @param handler
* A Handler to send messages back to the UI Activity
*/
public BluetoothService(Context context, Handler handler) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
mState = STATE_NONE;
mHandler = handler;
initializeArrayLists();
// 7 randomly-generated UUIDs. These must match on both server and
// client.
// mUuids.add(UUID.fromString("b7746a40-c758-4868-aa19-7ac6b3475dfc"));
// mUuids.add(UUID.fromString("2d64189d-5a2c-4511-a074-77f199fd0834"));
// mUuids.add(UUID.fromString("e442e09a-51f3-4a7b-91cb-f638491d1412"));
// mUuids.add(UUID.fromString("a81d6504-4536-49ee-a475-7d96d09439e4"));
// mUuids.add(UUID.fromString("aa91eab1-d8ad-448e-abdb-95ebba4a9b55"));
// mUuids.add(UUID.fromString("4d34da73-d0a4-4f40-ac38-917e0a9dee97"));
// mUuids.add(UUID.fromString("5e14d4df-9c8a-4db7-81e4-c937564c86e0"));
}
public static UUID getMY_UUID() {
return MY_UUID;
}
public static void setMY_UUID(UUID mY_UUID) {
MY_UUID = mY_UUID;
}
public boolean isDeviceConnectedAtPosition(int position) {
if (mConnThreads.get(position) == null) {
return false;
}
return true;
}
private void initializeArrayLists() {
mDeviceAddresses = new ArrayList<String>(5);
mDeviceNames = new ArrayList<String>(5);
mConnThreads = new ArrayList<ConnectedThread>(5);
mSockets = new ArrayList<BluetoothSocket>(5);
mUuids = new ArrayList<UUID>(5);
for (int i = 0; i < 5; i++) {
mDeviceAddresses.add(null);
mDeviceNames.add(null);
mConnThreads.add(null);
mSockets.add(null);
mUuids.add(null);
}
Log.i(TAG, "mConnThreads.size() in Service Constructor--"
+ mConnThreads.size());
}
public ArrayList<String> getmDeviceNames() {
return this.mDeviceNames;
}
public void setmDeviceNames(ArrayList<String> mDeviceNames) {
this.mDeviceNames = mDeviceNames;
}
public ArrayList<String> getmDeviceAddresses() {
return mDeviceAddresses;
}
public void setmDeviceAddresses(ArrayList<String> mDeviceAddresses) {
this.mDeviceAddresses = mDeviceAddresses;
}
/**
* Set the current state of the chat connection
*
* @param state
* An integer defining the current connection state
*/
private synchronized void setState(int state) {
if (D)
Log.d(TAG, "setState() " + mState + " -> " + state);
mState = state;
// Give the new state to the Handler so the UI Activity can update
mHandler.obtainMessage(ServerMainActivity.MESSAGE_STATE_CHANGE, state,
-1).sendToTarget();
}
/**
* Return the current connection state.
*/
public synchronized int getState() {
return mState;
}
/**
* Start the chat service. Specifically start AcceptThread to begin a
* session in listening (server) mode. Called by the Activity onResume()
*/
public synchronized void start() {
if (D)
Log.d(TAG, "start");
// Cancel any thread attempting to make a connection
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
// Cancel any thread currently running a connection
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
// Start the thread to listen on a BluetoothServerSocket
if (mAcceptThread == null) {
mAcceptThread = new AcceptThread();
mAcceptThread.start();
}
setState(STATE_LISTEN);
}
/**
* Start the ConnectThread to initiate a connection to a remote device.
*
* @param device
* The BluetoothDevice to connect
*/
public synchronized void connect(BluetoothDevice device,
int selectedPosition) {
if (getPositionIndexOfDevice(device) == -1) {
if (D)
Log.d(TAG, "connect to: " + device);
// Cancel any thread attempting to make a connection
if (mState == STATE_CONNECTING) {
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
}
// Cancel any thread currently running a connection
if (mConnThreads.get(selectedPosition) != null) {
mConnThreads.get(selectedPosition).cancel();
// mConnectedThread = null;
mConnThreads.set(selectedPosition, null);
}
// Create a new thread and attempt to connect to each UUID
// one-by-one.
try {
// String
// s="00001101-0000-1000-8000"+device.getAddress().split(":");
ConnectThread mConnectThread = new ConnectThread(device,
UUID.fromString("00001101-0000-1000-8000-"
+ device.getAddress().replace(":", "")),
selectedPosition);
Log.i(TAG, "uuid-string at server side"
+ ("00001101-0000-1000-8000" + device.getAddress()
.replace(":", "")));
mConnectThread.start();
setState(STATE_CONNECTING);
} catch (Exception e) {
}
} else {
Message msg = mHandler
.obtainMessage(ServerMainActivity.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(ServerMainActivity.TOAST,
"This device " + device.getName() + " Already Connected");
msg.setData(bundle);
mHandler.sendMessage(msg);
}
}
/**
* Start the ConnectedThread to begin managing a Bluetooth connection
*
* @param socket
* The BluetoothSocket on which the connection was made
* @param device
* The BluetoothDevice that has been connected
*/
public synchronized void connected(BluetoothSocket socket,
BluetoothDevice device, int selectedPosition) {
if (D)
Log.d(TAG, "connected");
/*
* // Cancel the thread that completed the connection if (mConnectThread
* != null) { mConnectThread.cancel(); mConnectThread = null; }
*
* // Cancel any thread currently running a connection if
* (mConnectedThread != null) { mConnectedThread.cancel();
* mConnectedThread = null; }
*
* // Cancel the accept thread because we only want to connect to one //
* device if (mAcceptThread != null) { mAcceptThread.cancel();
* mAcceptThread = null; }
*/
// Start the thread to manage the connection and perform transmissions
ConnectedThread mConnectedThread = new ConnectedThread(socket);
mConnectedThread.start();
// Add each connected thread to an array
mConnThreads.set(selectedPosition, mConnectedThread);
// Send the name of the connected device back to the UI Activity
Message msg = mHandler
.obtainMessage(ServerMainActivity.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(ServerMainActivity.DEVICE_NAME, device.getName());
msg.setData(bundle);
mHandler.sendMessage(msg);
setState(STATE_CONNECTED);
}
/**
* Stop all threads
*/
public synchronized void stop() {
if (D)
Log.d(TAG, "stop");
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null) {
mConnectedThread.cancel();
mConnectedThread = null;
}
if (mAcceptThread != null) {
mAcceptThread.cancel();
mAcceptThread = null;
}
for (int i = 0; i < 5; i++) {
mDeviceNames.set(i, null);
mDeviceAddresses.set(i, null);
mSockets.set(i, null);
if (mConnThreads.get(i) != null) {
mConnThreads.get(i).cancel();
mConnThreads.set(i, null);
}
}
setState(STATE_NONE);
}
/**
* Write to the ConnectedThread in an unsynchronized manner
*
* @param out
* The bytes to write
* @see ConnectedThread#write(byte[])
*/
public void write(byte[] out) {
// When writing, try to write out to all connected threads
for (int i = 0; i < mConnThreads.size(); i++) {
try {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (mState != STATE_CONNECTED)
return;
r = mConnThreads.get(i);
}
// Perform the write unsynchronized
r.write(out);
} catch (Exception e) {
}
}
}
/**
* Indicate that the connection attempt failed and notify the UI Activity.
*/
private void connectionFailed() {
setState(STATE_LISTEN);
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(ServerMainActivity.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(ServerMainActivity.TOAST, "Unable to connect device");
msg.setData(bundle);
mHandler.sendMessage(msg);
}
/**
* Indicate that the connection was lost and notify the UI Activity.
*/
private void connectionLost(BluetoothDevice device) {
// setState(STATE_LISTEN);
int positionIndex = getPositionIndexOfDevice(device);
if (positionIndex != -1) {
Log.i(TAG, "getPositionIndexOfDevice(device) ==="
+ mDeviceAddresses.get(getPositionIndexOfDevice(device)));
mDeviceAddresses.set(positionIndex, null);
mDeviceNames.set(positionIndex, null);
mConnThreads.set(positionIndex, null);
Message msg = mHandler
.obtainMessage(ServerMainActivity.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(ServerMainActivity.TOAST,
"Device connection was lost from " + device.getName());
msg.setData(bundle);
mHandler.sendMessage(msg);
}
// Send a failure message back to the Activity
}
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket mmServerSocket;
public AcceptThread() {
BluetoothServerSocket tmp = null;
// Create a new listening server socket
try {
if (mAdapter.isEnabled()) {
BluetoothService.setMY_UUID(UUID
.fromString("00001101-0000-1000-8000-"
+ mAdapter.getAddress().replace(":", "")));
}
Log.i(TAG, "MY_UUID.toString()=="
+ BluetoothService.getMY_UUID().toString());
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME,
BluetoothService.getMY_UUID());
} catch (IOException e) {
Log.e(TAG, "listen() failed", e);
}
mmServerSocket = tmp;
}
public void run() {
if (D)
Log.d(TAG, "BEGIN mAcceptThread" + this);
setName("AcceptThread");
BluetoothSocket socket = null;
Log.i(TAG, "mState in acceptThread==" + mState);
// Listen to the server socket if we're not connected
while (mState != STATE_CONNECTED) {
try {
// This is a blocking call and will only return on a
// successful connection or an exception
socket = mmServerSocket.accept();
} catch (IOException e) {
Log.e(TAG, "accept() failed", e);
break;
}
// If a connection was accepted
if (socket != null) {
synchronized (BluetoothService.this) {
switch (mState) {
case STATE_LISTEN:
case STATE_CONNECTING:
// Situation normal. Start the connected thread.
connected(socket, socket.getRemoteDevice(),getAvailablePositionIndexForNewConnection(socket.getRemoteDevice()));
break;
case STATE_NONE:
case STATE_CONNECTED:
// Either not ready or already connected. Terminate
// new socket.
try {
socket.close();
} catch (IOException e) {
Log.e(TAG, "Could not close unwanted socket", e);
}
break;
}
}
}
}
if (D)
Log.i(TAG, "END mAcceptThread");
}
public void cancel() {
if (D)
Log.d(TAG, "cancel " + this);
try {
mmServerSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of server failed", e);
}
}
}
/**
* This thread runs while listening for incoming connections. It behaves
* like a server-side client. It runs until a connection is accepted (or
* until cancelled).
*/
// private class AcceptThread extends Thread {
// BluetoothServerSocket serverSocket = null;
//
// public AcceptThread() {
// }
//
// public void run() {
// if (D)
// Log.d(TAG, "BEGIN mAcceptThread" + this);
// setName("AcceptThread");
// BluetoothSocket socket = null;
// try {
// // Listen for all 7 UUIDs
// serverSocket = mAdapter.listenUsingRfcommWithServiceRecord(
// NAME, MY_UUID);
// socket = serverSocket.accept();
// if (socket != null) {
// String address = socket.getRemoteDevice().getAddress();
// mSockets.add(socket);
// mDeviceAddresses.add(address);
// mDeviceNames.add(socket.getRemoteDevice().getName());
// // connected(socket, socket.getRemoteDevice());
// }
// } catch (IOException e) {
// Log.e(TAG, "accept() failed", e);
// }
// if (D)
// Log.i(TAG, "END mAcceptThread");
// }
//
// public void cancel() {
// if (D)
// Log.d(TAG, "cancel " + this);
// try {
// serverSocket.close();
// } catch (IOException e) {
// Log.e(TAG, "close() of server failed", e);
// }
// }
// }
/**
* This thread runs while attempting to make an outgoing connection with a
* device. It runs straight through; the connection either succeeds or
* fails.
*/
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
private UUID tempUuid;
private int selectedPosition;
public ConnectThread(BluetoothDevice device, UUID uuidToTry,
int selectedPosition) {
mmDevice = device;
BluetoothSocket tmp = null;
tempUuid = uuidToTry;
this.selectedPosition = selectedPosition;
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
tmp = device.createRfcommSocketToServiceRecord(uuidToTry);
} catch (IOException e) {
Log.e(TAG, "create() failed", e);
}
mmSocket = tmp;
}
public void run() {
Log.i(TAG, "BEGIN mConnectThread");
setName("ConnectThread");
// Always cancel discovery because it will slow down a connection
mAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
// This is a blocking call and will only return on a
// successful connection or an exception
mmSocket.connect();
} catch (IOException e) {
// if
// (tempUuid.toString().contentEquals(mUuids.get(6).toString()))
// {
connectionFailed();
// }
// Close the socket
try {
mmSocket.close();
} catch (IOException e2) {
Log.e(TAG,
"unable to close() socket during connection failure",
e2);
}
// Start the service over to restart listening mode
BluetoothService.this.start();
return;
}
// Reset the ConnectThread because we're done
synchronized (BluetoothService.this) {
mConnectThread = null;
}
mDeviceAddresses.set(selectedPosition, mmDevice.getAddress());
mDeviceNames.set(selectedPosition, mmDevice.getName());
// Start the connected thread
connected(mmSocket, mmDevice, selectedPosition);
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}
/**
* This thread runs during a connection with a remote device. It handles all
* incoming and outgoing transmissions.
*/
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(TAG, "create ConnectedThread");
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(
ServerMainActivity.MESSAGE_READ,
bytes,
getPositionIndexOfDevice(mmSocket.getRemoteDevice()),
buffer).sendToTarget();
Log.i("**********read", "read Called........");
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost(mmSocket.getRemoteDevice());
break;
}
}
}
/**
* Write to the connected OutStream.
*
* @param buffer
* The bytes to write
*/
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
// Share the sent message back to the UI Activity
mHandler.obtainMessage(ServerMainActivity.MESSAGE_WRITE, -1,
-1, buffer).sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Exception during write", e);
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}
public int getPositionIndexOfDevice(BluetoothDevice device) {
for (int i = 0; i < mDeviceAddresses.size(); i++) {
if (mDeviceAddresses.get(i) != null
&& mDeviceAddresses.get(i).equalsIgnoreCase(
device.getAddress()))
return i;
}
return -1;
}
public int getAvailablePositionIndexForNewConnection(BluetoothDevice device) {
if (getPositionIndexOfDevice(device) == -1) {
for (int i = 0; i < mDeviceAddresses.size(); i++) {
if (mDeviceAddresses.get(i) == null) {
return i;
}
}
}
return -1;
}
}
I implemented that with sucess after a relevant amount of work, during the path i faced some tricky bugs, for instance I had to implement a Handshake protocol(something like that) to avoid timeout problem during a connection attempt.
Well, I started looking at the BluetoothChat example(Android SDK Sample), that implements communication between 2 devices. So, I modified that, to permit multiple connections. As the code became large, i will just tell you the approach I have used.
Basically, all devices running my app can be a server or client. So each one, has always a BluetoothServerSocket(AcceptThread) running, so in this way, each device is always able to receive a request connection.
A device that wants to connect, starts a ConnectThread, this thread it is started after a discovery process or if it choose BluetoothDevice of PairedDevices Using getBondedDevices.
When a connection is established, I create a new Thread(ConnectedThread) that represents that connection. If you want to has different behavior that depends of you device role(master or slave) you can have a ConnectedThread subclass like MasterThread and SlaveThread
The Android Documentation has a good explanation of how to work with Bluetooth at: http://developer.android.com/guide/topics/connectivity/bluetooth.html
来源：https://stackoverflow.com/questions/13497103/multi-connection-via-bluetooth-in-android