安卓实现低功耗蓝牙从初始化到发送数据的完整代码

在Android上实现低功耗蓝牙(Low Energy Bluetooth, LE)通信通常需要使用Bluetooth Low Energy API。以下是使用Android官方库`bluetooth.le`实现从初始化到发送数据的基本步骤：

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;

//... (在你的Activity或Fragment中)

private BluetoothAdapter bleAdapter;
private BluetoothGatt gatt;

// 在onCreate()中初始化蓝牙
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // 获取蓝牙管理器
    BluetoothManager manager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
    bleAdapter = manager.getAdapter();

    if (bleAdapter == null) {
        Log.e(TAG, "Bluetooth is not available");
        return;
    }

    // 检查是否支持LE蓝牙
    if (!bleAdapter.isEnabled()) {
        Intent enableBleIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBleIntent, REQUEST_ENABLE_BT);
    } else {
        // 初始化扫描并连接设备
        startScan();
    }
}

// 扫描附近的LE设备
private void startScan() {
    BluetoothLeScanner scanner = bleAdapter.getBluetoothLeScanner();
    ScanSettings.Builder scanSettingsBuilder = new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
            .setReportDelay(0); // 设置报告延迟以提高响应速度
    ScanFilter.Builder filterBuilder = new ScanFilter.Builder()
            .setServiceUuid(new ParcelUuid(SERVICE_UUID)) // 替换为你服务的UUID
            .build();
    scanner.startScan(filterBuilder.build(), scanSettingsBuilder.build(), this::onScanResult);
}

// 当找到设备时，连接它
private void onScanResult(BluetoothDevice device, int rssi, byte[] scanRecord) {
    if (device.connectGatt(this, false, gattCallback)) { // 创建GattCallback
        Log.i(TAG, "Connected to: " + device.getName());
    } else {
        Log.e(TAG, "Failed to connect to: " + device.getAddress());
    }
}

// GATT回调
private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        switch (newState) {
            case BluetoothProfile.STATE_CONNECTED:
                discoverServices();
                break;
            // ...其他状态处理
        }
    }

    private void discoverServices() {
        gatt.discoverServices(); // 发现服务
        gatt.setCharacteristicNotification(SERVICE_CHARACTERISTIC_ID, true); // 订阅特性通知

        BluetoothGattDescriptor descriptor = gatt.getService(SERVICE_UUID).getCharacteristic(SERVICE_CHARACTERISTIC_ID).getDescriptor(NOTIFICATION_DESCRIPTOR_UUID);
        descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE); // 开启通知

        gatt.writeDescriptor(descriptor); // 写入描述符设置通知
    }

    // 发送数据
    @Override
    public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            sendData(characteristic.getValue()); // 根据实际数据格式发送数据
        } else {
            Log.e(TAG, "Write characteristic failed with status: " + status);
        }
    }

    // ...其他回调处理
};

// 发送数据的具体实现
private void sendData(byte[] data) {
    BluetoothGattCharacteristic writeChar = ...; // 创建你要写的特性
    gatt.writeCharacteristic(writeChar, data, BluetoothGatt.GATT_WRITE_TYPE_DEFAULT); // 写入数据
}

// ... (在onActivityResult()中关闭扫描和连接等操作)

请注意，以上代码是一个简化示例，实际应用中可能还需要处理错误、异常以及更多的交互逻辑。你需要替换`SERVICE_UUID`, `SERVICE_CHARACTERISTIC_ID`, 和 `NOTIFICATION_DESCRIPTOR_UUID`为你的蓝牙服务和特性的UUID。同时，发送的数据结构也要按照特定的协议进行编码。