我想向BLE设备发送消息。在我的理解中,首先必须发现设备服务,然后将消息发送到服务特征。所以这就是我所做的:
public class BluetoothLeService extends Service {
private BluetoothManager mBluetoothManager;
private BluetoothAdapter mBluetoothAdapter;
private String mBluetoothDeviceAddress;
private BluetoothGatt mBluetoothGatt;
private String macAddress;
private String serviceUuid;
private String characteristicUuid;
private Application app;
private int transmissionValue = 450;
public BluetoothLeService(String address, String serviceUuid, String characteristicUuid) {
this.macAddress = address;
this.serviceUuid = serviceUuid;
this.characteristicUuid = characteristicUuid;
}
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
System.out.println("connectionStateChange: " + status);
if (STATE_CONNECTED == newState) {
gatt.discoverServices();
}
}
@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if(gatt.getDevice().getName().equals("MyDeviceName")) {
sendMessageAfterDiscovery(gatt);
}
}
};
public boolean initialize(Application app) {
this.app = app;
if (mBluetoothManager == null) {
mBluetoothManager = (BluetoothManager) app.getSystemService(Context.BLUETOOTH_SERVICE);
if (mBluetoothManager == null) {
return false;
}
}
mBluetoothAdapter = mBluetoothManager.getAdapter();
if (mBluetoothAdapter == null) {
return false;
}
return true;
}
public boolean connect() {
return connect(macAddress);
}
public boolean connect(final String address) {
this.macAddress = address;
if (mBluetoothAdapter == null || macAddress == null) {
return false;
}
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(macAddress);
if (device == null) {
Log.w(TAG, "Device not found. Unable to connect.");
return false;
}
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
return true;
}
public void writeCharacteristic(int value) {
this.transmissionValue = value;
BluetoothDevice mDevice = mBluetoothAdapter.getRemoteDevice(this.macAddress);
BluetoothGatt mBG = mDevice.connectGatt(app.getApplicationContext(), true, mGattCallback);
System.out.println("device name: " + mBG.getDevice().getName());
}
private void sendMessageAfterDiscovery(BluetoothGatt gatt) {
BluetoothGattService mSVC = gatt.getService(UUID.fromString(serviceUuid));
BluetoothGattCharacteristic mCH = mSVC.getCharacteristic(UUID.fromString(characteristicUuid));
mCH.setValue(transmissionValue, BluetoothGattCharacteristic.FORMAT_UINT16, 0);
System.out.println("characteristic writable: " + isCharacteristicWriteable(mCH));
System.out.println("success? " + gatt.writeCharacteristic(mCH));
}
public static boolean isCharacteristicWriteable(BluetoothGattCharacteristic pChar) {
return (pChar.getProperties() & (BluetoothGattCharacteristic.PROPERTY_WRITE | BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE)) != 0;
}
}
以下是我要发送消息的代码:
private void sendMessage() {
BluetoothLeService ble = new BluetoothLeService("B0:00:00:00:00:C0", "0000fff0-1111-0000-0000-00805f9b34fb","0000fff1-1111-0000-0000-00805f9b34fb");
ble.initialize(app);
ble.connect();,
ble.writeCharacteristic(450)
}
现在,每当我想连接到设备并向其发送消息时,即使设备被识别,也永远不会调用onServiceDiscovered方法,因为我可以获取设备的名称。也没有抛出任何错误。
为什么这个方法永远不会被调用?难道我做错了什么? 我已经检查了权限,并在清单中将该类添加为服务。
感谢您的帮助......
答案 0 :(得分:1)
您需要在GATT回调的onConnectionStateChange
方法中拨打discoverServices
。 discoverServices
方法的文档:
发现远程设备提供的服务及其服务 特征和描述符。
这是一个异步操作。一旦发现服务 完成后,
onServicesDiscovered(BluetoothGatt, int)
回调就是 触发。如果发现成功,则远程服务可以 使用getServices()
函数检索。
在您的情况下,按如下方式更新代码应该可以解决问题:
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
System.out.println("connectionStateChange: " + status);
if (STATE_CONNECTED == newState) {
gatt.discoverServices();
}
}