This is the class where the connection is established and messages are recieved. Make sure to pair the devices before you run the application. If you want to have a slave/master connection, where each slave can only send messages to the master , and the master can broadcast messages to all slaves. You should only pair the master with each slave , but you shouldn't pair the slaves together.
package com.example.gaby.coordinatorv1;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Set;
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 android.widget.Toast;
public class Piconet {
private final static String TAG = Piconet.class.getSimpleName();
// Name for the SDP record when creating server socket
private static final String PICONET = "ANDROID_PICONET_BLUETOOTH";
private final BluetoothAdapter mBluetoothAdapter;
// String: device address
// BluetoothSocket: socket that represent a bluetooth connection
private HashMap<String, BluetoothSocket> mBtSockets;
// String: device address
// Thread: thread for connection
private HashMap<String, Thread> mBtConnectionThreads;
private ArrayList<UUID> mUuidList;
private ArrayList<String> mBtDeviceAddresses;
private Context context;
private Handler handler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case 1:
Toast.makeText(context, msg.getData().getString("msg"), Toast.LENGTH_SHORT).show();
break;
default:
break;
}
};
};
public Piconet(Context context) {
this.context = context;
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
mBtSockets = new HashMap<String, BluetoothSocket>();
mBtConnectionThreads = new HashMap<String, Thread>();
mUuidList = new ArrayList<UUID>();
mBtDeviceAddresses = new ArrayList<String>();
// Allow up to 7 devices to connect to the server
mUuidList.add(UUID.fromString("a60f35f0-b93a-11de-8a39-08002009c666"));
mUuidList.add(UUID.fromString("54d1cc90-1169-11e2-892e-0800200c9a66"));
mUuidList.add(UUID.fromString("6acffcb0-1169-11e2-892e-0800200c9a66"));
mUuidList.add(UUID.fromString("7b977d20-1169-11e2-892e-0800200c9a66"));
mUuidList.add(UUID.fromString("815473d0-1169-11e2-892e-0800200c9a66"));
mUuidList.add(UUID.fromString("503c7434-bc23-11de-8a39-0800200c9a66"));
mUuidList.add(UUID.fromString("503c7435-bc23-11de-8a39-0800200c9a66"));
Thread connectionProvider = new Thread(new ConnectionProvider());
connectionProvider.start();
}
public void startPiconet() {
Log.d(TAG, " -- Looking devices -- ");
// The devices must be already paired
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter
.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
// X , Y and Z are the Bluetooth name (ID) for each device you want to connect to
if (device != null && (device.getName().equalsIgnoreCase("X") || device.getName().equalsIgnoreCase("Y")
|| device.getName().equalsIgnoreCase("Z") || device.getName().equalsIgnoreCase("M"))) {
Log.d(TAG, " -- Device " + device.getName() + " found --");
BluetoothDevice remoteDevice = mBluetoothAdapter
.getRemoteDevice(device.getAddress());
connect(remoteDevice);
}
}
} else {
Toast.makeText(context, "No paired devices", Toast.LENGTH_SHORT).show();
}
}
private class ConnectionProvider implements Runnable {
@Override
public void run() {
try {
for (int i=0; i<mUuidList.size(); i++) {
BluetoothServerSocket myServerSocket = mBluetoothAdapter
.listenUsingRfcommWithServiceRecord(PICONET, mUuidList.get(i));
Log.d(TAG, " ** Opened connection for uuid " + i + " ** ");
// This is a blocking call and will only return on a
// successful connection or an exception
Log.d(TAG, " ** Waiting connection for socket " + i + " ** ");
BluetoothSocket myBTsocket = myServerSocket.accept();
Log.d(TAG, " ** Socket accept for uuid " + i + " ** ");
try {
// Close the socket now that the
// connection has been made.
myServerSocket.close();
} catch (IOException e) {
Log.e(TAG, " ** IOException when trying to close serverSocket ** ");
}
if (myBTsocket != null) {
String address = myBTsocket.getRemoteDevice().getAddress();
mBtSockets.put(address, myBTsocket);
mBtDeviceAddresses.add(address);
Thread mBtConnectionThread = new Thread(new BluetoohConnection(myBTsocket));
mBtConnectionThread.start();
Log.i(TAG," ** Adding " + address + " in mBtDeviceAddresses ** ");
mBtConnectionThreads.put(address, mBtConnectionThread);
} else {
Log.e(TAG, " ** Can't establish connection ** ");
}
}
} catch (IOException e) {
Log.e(TAG, " ** IOException in ConnectionService:ConnectionProvider ** ", e);
}
}
}
private class BluetoohConnection implements Runnable {
private String address;
private final InputStream mmInStream;
public BluetoohConnection(BluetoothSocket btSocket) {
InputStream tmpIn = null;
try {
tmpIn = new DataInputStream(btSocket.getInputStream());
} catch (IOException e) {
Log.e(TAG, " ** IOException on create InputStream object ** ", e);
}
mmInStream = tmpIn;
}
@Override
public void run() {
byte[] buffer = new byte[1];
String message = "";
while (true) {
try {
int readByte = mmInStream.read();
if (readByte == -1) {
Log.e(TAG, "Discarting message: " + message);
message = "";
continue;
}
buffer[0] = (byte) readByte;
if (readByte == 0) { // see terminateFlag on write method
onReceive(message);
message = "";
} else { // a message has been recieved
message += new String(buffer, 0, 1);
}
} catch (IOException e) {
Log.e(TAG, " ** disconnected ** ", e);
}
mBtDeviceAddresses.remove(address);
mBtSockets.remove(address);
mBtConnectionThreads.remove(address);
}
}
}
/**
* @param receiveMessage
*/
private void onReceive(String receiveMessage) {
if (receiveMessage != null && receiveMessage.length() > 0) {
Log.i(TAG, " $$$$ " + receiveMessage + " $$$$ ");
Bundle bundle = new Bundle();
bundle.putString("msg", receiveMessage);
Message message = new Message();
message.what = 1;
message.setData(bundle);
handler.sendMessage(message);
}
}
/**
* @param device
* @param uuidToTry
* @return
*/
private BluetoothSocket getConnectedSocket(BluetoothDevice device, UUID uuidToTry) {
BluetoothSocket myBtSocket;
try {
myBtSocket = device.createRfcommSocketToServiceRecord(uuidToTry);
myBtSocket.connect();
return myBtSocket;
} catch (IOException e) {
Log.e(TAG, "IOException in getConnectedSocket", e);
}
return null;
}
private void connect(BluetoothDevice device) {
BluetoothSocket myBtSocket = null;
String address = device.getAddress();
BluetoothDevice remoteDevice = mBluetoothAdapter.getRemoteDevice(address);
// Try to get connection through all uuids available
for (int i = 0; i < mUuidList.size() && myBtSocket == null; i++) {
// Try to get the socket 2 times for each uuid of the list
for (int j = 0; j < 2 && myBtSocket == null; j++) {
Log.d(TAG, " ** Trying connection..." + j + " with " + device.getName() + ", uuid " + i + "...** ");
myBtSocket = getConnectedSocket(remoteDevice, mUuidList.get(i));
if (myBtSocket == null) {
try {
Thread.sleep(200);
} catch (InterruptedException e) {
Log.e(TAG, "InterruptedException in connect", e);
}
}
}
}
if (myBtSocket == null) {
Log.e(TAG, " ** Could not connect ** ");
return;
}
Log.d(TAG, " ** Connection established with " + device.getName() +"! ** ");
mBtSockets.put(address, myBtSocket);
mBtDeviceAddresses.add(address);
Thread mBluetoohConnectionThread = new Thread(new BluetoohConnection(myBtSocket));
mBluetoohConnectionThread.start();
mBtConnectionThreads.put(address, mBluetoohConnectionThread);
}
public void bluetoothBroadcastMessage(String message) {
//send message to all except Id
for (int i = 0; i < mBtDeviceAddresses.size(); i++) {
sendMessage(mBtDeviceAddresses.get(i), message);
}
}
private void sendMessage(String destination, String message) {
BluetoothSocket myBsock = mBtSockets.get(destination);
if (myBsock != null) {
try {
OutputStream outStream = myBsock.getOutputStream();
final int pieceSize = 16;
for (int i = 0; i < message.length(); i += pieceSize) {
byte[] send = message.substring(i,
Math.min(message.length(), i + pieceSize)).getBytes();
outStream.write(send);
}
// we put at the end of message a character to sinalize that message
// was finished
byte[] terminateFlag = new byte[1];
terminateFlag[0] = 0; // ascii table value NULL (code 0)
outStream.write(new byte[1]);
} catch (IOException e) {
Log.d(TAG, "line 278", e);
}
}
}
}
Your main activity should be as follow :
package com.example.gaby.coordinatorv1;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
private Button discoveryButton;
private Button messageButton;
private Piconet piconet;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
piconet = new Piconet(getApplicationContext());
messageButton = (Button) findViewById(R.id.messageButton);
messageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
piconet.bluetoothBroadcastMessage("Hello World---*Gaby Bou Tayeh*");
}
});
discoveryButton = (Button) findViewById(R.id.discoveryButton);
discoveryButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
piconet.startPiconet();
}
});
}
}
And here's the XML Layout :
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<Button
android:id="@+id/discoveryButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Discover"
/>
<Button
android:id="@+id/messageButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send message"
/>
Do not forget to add the following permissions to your Manifest File :
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />