写一个Android GATT服务端定期广播电池电量数据
时间: 2024-05-11 17:17:58 浏览: 4
在 Android 中,可以使用 BluetoothGattServer 类实现 GATT 服务端。下面是一个实现定期广播电池电量数据的例子:
首先,需要在 AndroidManifest.xml 文件中添加以下权限:
```xml
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
```
然后,创建一个 BluetoothGattServerCallback 的实例,用于处理 GATT 服务端的事件:
```java
private BluetoothGattServerCallback mGattServerCallback = new BluetoothGattServerCallback() {
@Override
public void onConnectionStateChange(BluetoothDevice device, int status, int newState) {
super.onConnectionStateChange(device, status, newState);
// 处理连接状态改变的事件
}
@Override
public void onCharacteristicReadRequest(BluetoothDevice device, int requestId, int offset, BluetoothGattCharacteristic characteristic) {
super.onCharacteristicReadRequest(device, requestId, offset, characteristic);
// 处理读取特征值请求的事件
}
@Override
public void onCharacteristicWriteRequest(BluetoothDevice device, int requestId, BluetoothGattCharacteristic characteristic, boolean preparedWrite, boolean responseNeeded, int offset, byte[] value) {
super.onCharacteristicWriteRequest(device, requestId, characteristic, preparedWrite, responseNeeded, offset, value);
// 处理写入特征值请求的事件
}
// 其他事件的处理方法
};
```
接下来,在 onCreate() 方法中创建 BluetoothGattServer 实例,并添加一个电池电量的特征值:
```java
private BluetoothGattServer mGattServer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
BluetoothAdapter bluetoothAdapter = bluetoothManager.getAdapter();
mGattServer = bluetoothManager.openGattServer(this, mGattServerCallback);
BluetoothGattService batteryService = new BluetoothGattService(UUID.fromString(BATTERY_SERVICE_UUID), BluetoothGattService.SERVICE_TYPE_PRIMARY);
BluetoothGattCharacteristic batteryLevelCharacteristic = new BluetoothGattCharacteristic(UUID.fromString(BATTERY_LEVEL_UUID), BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_NOTIFY, BluetoothGattCharacteristic.PERMISSION_READ);
batteryLevelCharacteristic.setValue(50, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
batteryService.addCharacteristic(batteryLevelCharacteristic);
mGattServer.addService(batteryService);
}
```
其中, BATTERY_SERVICE_UUID 和 BATTERY_LEVEL_UUID 分别是电池服务和电池电量特征值的 UUID,可以自定义。
接下来,在 onStart() 方法中设置广播电池电量数据的定时器:
```java
private Timer mBatteryTimer;
@Override
protected void onStart() {
super.onStart();
mBatteryTimer = new Timer();
mBatteryTimer.schedule(new TimerTask() {
@Override
public void run() {
BluetoothGattService batteryService = mGattServer.getService(UUID.fromString(BATTERY_SERVICE_UUID));
BluetoothGattCharacteristic batteryLevelCharacteristic = batteryService.getCharacteristic(UUID.fromString(BATTERY_LEVEL_UUID));
int batteryLevel = (int) (Math.random() * 100);
batteryLevelCharacteristic.setValue(batteryLevel, BluetoothGattCharacteristic.FORMAT_UINT8, 0);
for (BluetoothDevice device : mGattServer.getConnectedDevices()) {
mGattServer.notifyCharacteristicChanged(device, batteryLevelCharacteristic, false);
}
}
}, 0, 5000);
}
```
其中,定时器每隔 5 秒钟就会更新电池电量特征值,并使用 notifyCharacteristicChanged() 方法广播该特征值的数据。
最后,在 onStop() 方法中停止定时器,并关闭 GATT 服务端:
```java
@Override
protected void onStop() {
super.onStop();
mBatteryTimer.cancel();
mBatteryTimer = null;
mGattServer.clearServices();
mGattServer.close();
mGattServer = null;
}
```
完成上述步骤后,就可以在 Android 设备上实现一个 GATT 服务端,定期广播电池电量数据了。