从android应用程序中的ble连续读取数据
作者:互联网
我想通过蓝牙在android应用程序中连续从ble硬件读取数据.
连接已完成,我可以将数据从应用程序发送到ble,但是无法从ble读取数据.
从ble获取一些数据时必须调用onCharactersticChanged方法,但此回调方法未调用.我想通知ble但
writeChar.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
BluetoothGattDescriptor descriptor = new BluetoothGattDescriptor(BLEUtils.CLIENT_CHARACTERISTIC_CONFIG_UUID, BluetoothGattDescriptor.PERMISSION_WRITE_SIGNED);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);
// Enable local notifications
gatt.setCharacteristicNotification(writeChar, true);
boolean succes = gatt.writeDescriptor(descriptor);
其返回假
解决方法:
我建议您在订阅特性时应设置ENABLE_NOTIFICATION_VALUE.这是我执行此操作的代码:
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
List<BluetoothGattService> services = getSupportedGattServices();
for (BluetoothGattService service : services) {
if (!service.getUuid().equals(UUID_TARGET_SERVICE))
continue;
List<BluetoothGattCharacteristic> gattCharacteristics =
service.getCharacteristics();
// Loops through available Characteristics.
for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
if (!gattCharacteristic.getUuid().equals(UUID_TARGET_CHARACTERISTIC))
continue;
final int charaProp = gattCharacteristic.getProperties();
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_NOTIFY) > 0) {
setCharacteristicNotification(gattCharacteristic, true);
} else {
Log.w(TAG, "Characteristic does not support notify");
}
}
}
} else {
Log.w(TAG, "onServicesDiscovered received: " + status);
}
}
那么您可以通过NOTIFICATION订阅特征:
public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic,
boolean enabled) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
Log.w(TAG, "BluetoothAdapter not initialized");
return;
}
mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID_DESCRIPTOR);
descriptor.setValue(enabled?BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
:BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE);
mBluetoothGatt.writeDescriptor(descriptor);
}
之后,您可以开始写入设备:
@Override
public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
if (descriptor.getCharacteristic().getUuid().equals(UUID_TARGET_CHARACTERISTIC)) {
Log.i(TAG, "Successfully subscribed");
}
byte[] data = <Your data here>;
BluetoothGattService Service = mBluetoothGatt.getService(UUID_TARGET_SERVICE);
BluetoothGattCharacteristic charac = Service
.getCharacteristic(UUID_TARGET_CHARACTERISTIC);
charac.setValue(data);
mBluetoothGatt.writeCharacteristic(charac);
} else {
Log.e(TAG, "Error subscribing");
}
}
并且您将收到回调onCharactersticChanged以进行读取,而无需实际调用读取操作.
请记住,mBluetoohGatt一次只能处理1个操作,如果您在上一个未完成的情况下执行另一个操作,则不会放入队列中,但会返回false.
标签:bluetooth,bluetooth-lowenergy,bluetooth-gatt,android 来源: https://codeday.me/bug/20191111/2021916.html