我编写了一个代码，当它发生变化时，我可以从该值中读取通知值。
但是我还需要读取设备的电池电量，这是来自仿真设备的另一项服务，但是每当我尝试读取电池电量时，第一部分甚至都不会从心率中发送通知值
代码如下：
public class MainActivity extends AppCompatActivity {
BluetoothManager btManager;
BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;
Button startScanningButton;
Button stopScanningButton;
TextView peripheralTextView;
private final static int REQUEST_ENABLE_BT = 1;
private static final int PERMISSION_REQUEST_COARSE_LOCATION = 1;
Boolean btScanning = false;
int deviceIndex = 0;
ArrayList<BluetoothDevice> devicesDiscovered = new ArrayList<BluetoothDevice>();
EditText deviceIndexInput;
Button connectToDevice;
Button disconnectDevice;
BluetoothGatt bluetoothGatt;
UUID HEART_RATE_SERVICE_UUID = convertFromInteger(0x180D);
UUID HEART_RATE_MEASUREMENT_CHAR_UUID = convertFromInteger(0x2A37);
UUID HEART_RATE_CONTROL_POINT_CHAR_UUID = convertFromInteger(0x2A39);
UUID CLIENT_CHARACTERISTIC_CONFIG_UUID = convertFromInteger(0x2902);
UUID BATTERY_LEVEL = convertFromInteger(0x2A19);
UUID BATTERY_SERVICE = convertFromInteger(0x180F);
public final static String ACTION_GATT_CONNECTED =
"com.example.bluetooth.le.ACTION_GATT_CONNECTED";
public final static String ACTION_GATT_DISCONNECTED =
"com.example.bluetooth.le.ACTION_GATT_DISCONNECTED";
public final static String ACTION_GATT_SERVICES_DISCOVERED =
"com.example.bluetooth.le.ACTION_GATT_SERVICES_DISCOVERED";
public final static String ACTION_DATA_AVAILABLE =
"com.example.bluetooth.le.ACTION_DATA_AVAILABLE";
public final static String EXTRA_DATA =
"com.example.bluetooth.le.EXTRA_DATA";
public Map<String, String> uuids = new HashMap<String, String>();
// Stops scanning after 5 seconds.
private Handler mHandler = new Handler();
private static final long SCAN_PERIOD = 1000;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
peripheralTextView = (TextView) findViewById(R.id.PeripheralTextView);
peripheralTextView.setMovementMethod(new ScrollingMovementMethod());
deviceIndexInput = (EditText) findViewById(R.id.InputIndex);
deviceIndexInput.setText("0");
connectToDevice = (Button) findViewById(R.id.ConnectButton);
connectToDevice.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
connectToDeviceSelected();
}
});
disconnectDevice = (Button) findViewById(R.id.DisconnectButton);
disconnectDevice.setVisibility(View.INVISIBLE);
disconnectDevice.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
disconnectDeviceSelected();
}
});
startScanningButton = (Button) findViewById(R.id.StartScanButton);
startScanningButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
startScanning();
}
});
stopScanningButton = (Button) findViewById(R.id.StopScanButton);
stopScanningButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
stopScanning();
}
});
stopScanningButton.setVisibility(View.INVISIBLE);
btManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
btAdapter = btManager.getAdapter();
btScanner = btAdapter.getBluetoothLeScanner();
if (btAdapter != null && !btAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
}
// Make sure we have access coarse location enabled, if not, prompt the user to enable it
/* if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("This app needs location access");
builder.setMessage("Please grant location access so this app can detect peripherals.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
@Override
public void onDismiss(DialogInterface dialog) {
requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);
}
});
builder.show();
}*/
//client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}
// Device scan callback.
private ScanCallback leScanCallback = new ScanCallback() {
@Override
public void onScanResult(int callbackType, ScanResult result) {
peripheralTextView.append("Index: " + deviceIndex + ", Device Name: " + result.getDevice().getName() + " rssi: " + result.getRssi() + ", MAC: " + result.getDevice().getAddress() + "\n");
devicesDiscovered.add(result.getDevice());
deviceIndex++;
// auto scroll for text view
final int scrollAmount = peripheralTextView.getLayout().getLineTop(peripheralTextView.getLineCount()) - peripheralTextView.getHeight();
// if there is no need to scroll, scrollAmount will be <=0
if (scrollAmount > 0) {
peripheralTextView.scrollTo(0, scrollAmount);
}
}
};
// Device connect call back
private final BluetoothGattCallback btleGattCallback = new BluetoothGattCallback() {
@Override
public void onCharacteristicChanged(BluetoothGatt gatt, final BluetoothGattCharacteristic characteristic) {
// this will get called anytime you perform a read or write characteristic operation
final byte[] teste = characteristic.getValue();
final String batida = teste.toString();
final String result = "result";
int format = BluetoothGattCharacteristic.FORMAT_UINT8;
final int heartRate = characteristic.getIntValue(format, 1);
String TAG = "d";
Log.d(TAG, String.format("Received heart rate: %d", heartRate));
Log.v(result , batida);
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("value of sensor (BPM) "+ heartRate + "\n");
}
});
}
@Override
public void onConnectionStateChange(final BluetoothGatt gatt, final int status, final int newState) {
// this will get called when a device connects or disconnects
System.out.println(newState);
switch (newState) {
case 0:
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("device disconnected\n");
connectToDevice.setVisibility(View.VISIBLE);
disconnectDevice.setVisibility(View.INVISIBLE);
}
});
break;
case 2:
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("device connected\n");
connectToDevice.setVisibility(View.INVISIBLE);
disconnectDevice.setVisibility(View.VISIBLE);
}
});
// discover services and characteristics for this device
bluetoothGatt.discoverServices();
break;
default:
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("we encounterned an unknown state, uh oh\n");
}
});
break;
}
}
@Override
public void onServicesDiscovered(final BluetoothGatt gatt, final int status) {
// this will get called after the client initiates a BluetoothGatt.discoverServices() call
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("device services have been discovered\n");
}
});
displayGattServices(bluetoothGatt.getServices());
BluetoothGattCharacteristic characteristic = gatt.getService(HEART_RATE_SERVICE_UUID).getCharacteristic(HEART_RATE_MEASUREMENT_CHAR_UUID);
//BluetoothGattCharacteristic battery = gatt.getService(BATTERY_SERVICE).getCharacteristic(BATTERY_LEVEL);
//gatt.readCharacteristic(battery);
gatt.setCharacteristicNotification(characteristic, true);
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(CLIENT_CHARACTERISTIC_CONFIG_UUID);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);
}
@Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
BluetoothGattCharacteristic characteristic = gatt.getService(HEART_RATE_SERVICE_UUID).getCharacteristic(HEART_RATE_CONTROL_POINT_CHAR_UUID);
characteristic.setValue(new byte[]{1,1});
gatt.writeCharacteristic(characteristic);
}
@Override
// Result of a characteristic read operation
public void onCharacteristicRead(BluetoothGatt gatt,
BluetoothGattCharacteristic characteristic,
int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
}
}
};
private void broadcastUpdate(final String action,
final BluetoothGattCharacteristic characteristic) {
System.out.println(characteristic.getUuid());
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_COARSE_LOCATION: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
System.out.println("coarse location permission granted");
} else {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Functionality limited");
builder.setMessage("Since location access has not been granted, this app will not be able to discover beacons when in the background.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
@Override
public void onDismiss(DialogInterface dialog) {
}
});
builder.show();
}
return;
}
}
}
public void startScanning() {
System.out.println("start scanning");
btScanning = true;
deviceIndex = 0;
devicesDiscovered.clear();
peripheralTextView.setText("");
peripheralTextView.append("Started Scanning\n");
startScanningButton.setVisibility(View.INVISIBLE);
stopScanningButton.setVisibility(View.VISIBLE);
AsyncTask.execute(new Runnable() {
@Override
public void run() {
btScanner.startScan(leScanCallback);
}
});
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
stopScanning();
}
}, SCAN_PERIOD);
}
public void stopScanning() {
System.out.println("stopping scanning");
peripheralTextView.append("Stopped Scanning\n");
btScanning = false;
startScanningButton.setVisibility(View.VISIBLE);
stopScanningButton.setVisibility(View.INVISIBLE);
AsyncTask.execute(new Runnable() {
@Override
public void run() {
btScanner.stopScan(leScanCallback);
}
});
}
public void connectToDeviceSelected() {
peripheralTextView.append("Trying to connect to device at index: " + deviceIndexInput.getText() + "\n");
int deviceSelected = Integer.parseInt(deviceIndexInput.getText().toString());
bluetoothGatt = devicesDiscovered.get(deviceSelected).connectGatt(this, false, btleGattCallback);
}
public void disconnectDeviceSelected() {
peripheralTextView.append("Disconnecting from device\n");
bluetoothGatt.disconnect();
}
private void displayGattServices(List<BluetoothGattService> gattServices) {
if (gattServices == null) return;
// Loops through available GATT Services.
for (BluetoothGattService gattService : gattServices) {
final String uuid = gattService.getUuid().toString();
System.out.println("Service discovered: " + uuid);
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("Service disovered: "+uuid+"\n");
}
});
new ArrayList<HashMap<String, String>>();
List<BluetoothGattCharacteristic> gattCharacteristics =
gattService.getCharacteristics();
// Loops through available Characteristics.
for (BluetoothGattCharacteristic gattCharacteristic :
gattCharacteristics) {
final String charUuid = gattCharacteristic.getUuid().toString();
System.out.println("Characteristic discovered for service: " + charUuid);
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
peripheralTextView.append("Characteristic discovered for service: "+charUuid+"\n");
}
});
}
}
}
@Override
public void onStart() {
super.onStart();
}
@Override
public void onStop() {
super.onStop();
}
public UUID convertFromInteger(int i) {
final long MSB = 0x0000000000001000L;
final long LSB = 0x800000805f9b34fbL;
long value = i & 0xFFFFFFFF;
return new UUID(MSB | (value << 32), LSB);
}
}
如何在不中断BLE通知的情况下阅读？
答案 0 :(得分：0)
如您所见，您不能同时启动这两个操作（第一个操作将被覆盖并且永远不会执行）：
gatt.readCharacteristic(battery);
gatt.writeDescriptor(descriptor);
相反，您必须执行第一个操作，等待它完成（在您的示例中，等待onCharacteristicRead被调用），然后然后开始第二个操作。一种常见的实现方法是使用queue存储待处理的操作，然后从队列的前面弹出项目，并在其余的代码中一次执行一个项目。
此必需的排队是Android BLE API的一个令人讨厌的方面，文档中未进行描述。有关更多详细信息，请查看我的talk或list of resources for Android BLE。