This is a work-in-progress Bluetooth LE / 4.0 library. Currently works with Heart Rate Monitors. I'll be using this for a production project, so the structure and API might change over time.
This depends on the Witness library.
- Simple to pull in and get a BLE heart rate monitor working
- Leverages an event emitter, Witness
- Remember last connected device
The first thing that we need to know is whether or not we've ever connected to a BLE device. This library assumes that there will be a single device that you will use.
Test to see if you have a stored device:
BlePrefs prefs = new BlePrefs((Context)this);
if (null == prefs.getConnectedDevice())
If you do have a stored device, you're in luck. All you need to do is start the BleHeartService, and it will automatically get you connected to the last known device.
startService(new Intent(this, BleHeartService.class));
If you do not have a stored device, it's a good idea to find and connect to one. Here's a look at our PairingActivity, which is responsible for displaying all of the devices that we've found:
public class PairingActivity extends Activity implements Reporter {
private Handler handler = new Handler();
// ...
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Witness.register(DeviceFound.class, this);
startService(new Intent(this, BleHeartService.class));
// probably create some adapter to add devices to
// ...
}
@Override
public void onDestroy() {
Witness.remove(DeviceFound.class, this);
super.onDestroy();
}
private void addDeviceToAdapter(final BluetoothDevice device) {
// add the device to the adapter
}
@Override
public void notifyEvent(final Object o) {
handler.post(new Runnable() {
@Override
public void run() {
if (o instanceof DeviceFound) {
// we found a device!
addDeviceToAdapter(((DeviceFound) o).device);
}
}
});
}
}
We now have a list of devices that we can connect to. Here's an example of how to connect to an item in an adapter:
// whenever we click on an item, we want to make sure to store it,
// start the service, and notify anything that needs to know
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// obviously, change this per your specific implementation
String address = mAdapter.getItem(position).getAddressString();
StoredBluetoothDevice device = BleScanner.getDevices().get(address);
// notify anyone listening
Witness.notify(new BleConnect(device.getDevice()));
// we need to set this here to avoid a race condition
prefs.setConnectedDevice(device.getDevice());
// I'm using startService because this is Glassware
// this kicks off the thing that is going to display the heart rate
startService(new Intent(PairingActivity.this, HeartyLiveCardService.class));
// get rid of the PairingActivity
finish();
}
});
We've connected, and now are kicking off our display:
public class HeartyLiveCardService extends Service implements Reporter {
private final Handler handler = new Handler();
@Override
public void onCreate() {
super.onCreate();
Witness.register(HeartRate.class, this);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
startService(new Intent(this, BleHeartService.class));
// build LiveCard for Glass
// ...
return START_STICKY;
}
@Override
public void onDestroy() {
Witness.remove(HeartRate.class, this);
super.onDestroy();
}
private void notifyHeartRate(HeartRate heartRate) {
// Set up initial RemoteViews values
mLiveCardView.setTextViewText(R.id.heart_rate,
String.valueOf(heartRate.getHeartRate()));
mLiveCard.setViews(mLiveCardView);
}
@Override
public void notifyEvent(final Object o) {
handler.post(new Runnable() {
@Override
public void run() {
if (o instanceof HeartRate) {
notifyHeartRate(((HeartRate) o));
}
}
});
}
}
That's pretty much it! At this point, you've successfully connected your device, and are displaying data.