Java 颤振Android BluetoothDevice.Action\u发现不工作

我正在使用flatter和Java本机代码进行蓝牙扫描。我已经设置了

BroadcastReceiver

，可以看到

BluetoothAdapter。操作\u发现\u已启动

和

BluetoothAdapter。操作\u发现\u已完成

被触发，但

BluetoothDevice。操作\u发现

不工作。有人能帮我吗

我目前正在安卓8.1.0手机上测试扫描。我已把这个计划付诸实施

AndroidManifest.xml文件：

<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.mobile">
  <uses-permission android:name="android.permission.BLUETOOTH" />
  <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
  <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
  <application android:name="io.flutter.app.FlutterApplication" android:label="mobile" android:icon="@mipmap/ic_launcher">
    <activity android:name=".MainActivity" android:launchMode="singleTop" android:theme="@style/LaunchTheme" android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode" android:hardwareAccelerated="true" android:windowSoftInputMode="adjustResize">
      <meta-data android:name="io.flutter.embedding.android.NormalTheme" android:resource="@style/NormalTheme" />
      <meta-data android:name="io.flutter.embedding.android.SplashScreenDrawable" android:resource="@drawable/launch_background" />
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <meta-data android:name="flutterEmbedding" android:value="2" />
  </application>
</manifest>

Java本机代码

android {
    compileSdkVersion 29
    lintOptions {
        disable 'InvalidPackage'
    }
    defaultConfig {
        applicationId "com.example.mobile"
        minSdkVersion 16
        targetSdkVersion 29
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }
}

// scan
    private void scanBluetoothDevices() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(receiver, filter);

        boolean isDiscovering = bluetoothAdapter.isDiscovering();
        if (isDiscovering) {
            System.out.println("Discovering in progress...");
            bluetoothAdapter.cancelDiscovery();
        }

        try {
            System.out.println("Start to do discovery...");
            boolean a = bluetoothAdapter.startDiscovery();
            System.out.println(a);
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    // Create a BroadcastReceiver for ACTION_FOUND.
    private final BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            try {
                String onReceiveAction = "current action: " + action;
                System.out.println(onReceiveAction);

                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    System.out.println("Action Found..........");
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    String deviceName = device.getName();
                    String deviceHardwareAddress = device.getAddress(); // MAC
                                                                        // address

                    System.out.println("***********************************");
                    System.out.println(deviceName);
                    System.out.println(deviceHardwareAddress);
                } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                    System.out.println("Discovery Finished..........");
                    scanResult();
                } else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
                    System.out.println("Discovery Started..........");
                }
            } catch (Exception e) {
                // TODO: handle exception
                System.out.println("got error in onReceive");
                e.printStackTrace();
            }

        }
    };

    private void scanResult() {
        bluetoothAdapter.cancelDiscovery();
        unregisterReceiver(receiver);
    }