android - 动态注册广播接收器不起作用 - BluetoothDevice.ACTION_FOUND

Question

使用 Log 类跟踪运行时显示 onReceive() 方法没有调用，为什么？

动态注册广播接收器

 private void discoverDevices () {
    Log.e("MOHAB","BEFORE ON RECEIVE");

     mReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            Log.e("MOHAB","ON RECEIVE");
            String action = intent.getAction();
            // When discovery finds a device
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                // Get the BluetoothDevice object from the Intent
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                // Add the name and address to an array adapter to show in a ListView
                Bluetooth b = new Bluetooth(device.getName(),device.getAddress());
                list.add(b);
            }
        }
    };
    Log.e("MOHAB","create intentFilter");
    // Register the BroadcastReceiver
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy

}

Answer 1

除了starting with Android 6.0 you have to have the ACCESS_COARSE_LOCATION permission to receive ACTION_FOUND (正如@siniux 已经提到的)，还有另一个相关的事情:

ACCESS_COARSE_LOCATION 在 dangerous permissions 中您必须在运行时向用户明确请求(6.0 中的另一项安全改进)。

要进行诊断，您可以运行 adb logcat | grep BroadcastQueue，然后看到类似这样的内容:

W/BroadcastQueue: Permission Denial: receiving Intent { 
    act=android.bluetooth.device.action.FOUND flg=0x10 (has extras) } 
    to ProcessRecord{9007:com.examplepackage} (pid=9007, uid=10492) 
    requires android.permission.ACCESS_COARSE_LOCATION due to sender
    com.android.bluetooth (uid 1002)

因此，在 Marshmallow 上发现 BT 设备的正确过程如下:

1. list 中有 ACCESS_COARSE_LOCATION 权限要求以及通常的蓝牙权限:

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

2. Ensure you have run-time permission对于 ACCESS_COARSE_LOCATION

   protected void checkLocationPermission() {
       if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
               != PackageManager.PERMISSION_GRANTED) {
   
           ActivityCompat.requestPermissions(this,
                   new String[]{Manifest.permission.ACCESS_COARSE_LOCATION},
                   REQUEST_COARSE_LOCATION);
       }
   }
   
   @Override
   public void onRequestPermissionsResult(int requestCode,
                                      String permissions[], int[] grantResults) {
       switch (requestCode) {
       case REQUEST_COARSE_LOCATION: {
           if (grantResults.length > 0
                   && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
               proceedDiscovery(); // --->
           } else {
               //TODO re-request
           }
           break;
       }
   }
   

3. 为 ACTION_FOUND 注册广播接收器并调用 BluetoothAdapter.startDiscovery()

   protected void proceedDiscovery() {
       IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
       filter.addAction(BluetoothDevice.ACTION_NAME_CHANGED);
       registerReceiver(mReceiver, filter);
   
       mBluetoothAdapter.startDiscovery();
   }
   

ACTION_NAME_CHANGED 的有趣之处。尽管 6.0 不会在未经粗略位置许可的情况下为您提供 ACTION_FOUND，但您仍然会收到 ACTION_NAME_CHANGED 事件，这些事件通常与 ACTION_FOUND 发现设备时。 IE。你得到了这两个事件，所以没有许可，你仍然可以处理 ACTION_NAME_CHANGED 几乎相同的行为。 (大师，如果我错了请纠正我)