android - 如何以编程方式判断蓝牙设备是否已连接？

Question

我了解如何获取已配对设备的列表，但如何判断它们是否已连接？

这一定是可能的，因为我看到它们列在我手机的蓝牙设备列表中，并说明了它们的连接状态。

Answer 1

将蓝牙权限添加到您的 AndroidManifest，

<uses-permission android:name="android.permission.BLUETOOTH" />

然后使用 Intent 过滤器监听 ACTION_ACL_CONNECTED、ACTION_ACL_DISCONNECT_REQUESTED 和 ACTION_ACL_DISCONNECTED 广播:

public void onCreate() {
    ...
    IntentFilter filter = new IntentFilter();
    filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
    filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
    filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
    this.registerReceiver(mReceiver, filter);
}

//The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
           ... //Device found
        }
        else if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
           ... //Device is now connected
        }
        else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
           ... //Done searching
        }
        else if (BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED.equals(action)) {
           ... //Device is about to disconnect
        }
        else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
           ... //Device has disconnected
        }
    }
};

---

几点说明:

• 无法在应用启动时检索已连接设备的列表。蓝牙 API 不允许您查询，而是允许您收听更改。
• 解决上述问题的一个好方法是检索所有已知/配对设备的列表...然后尝试连接每个设备(以确定您是否已连接)。
• 或者，您可以让后台服务监视蓝牙 API 并将设备状态写入磁盘，以供您的应用日后使用。