Android广播接收器蓝牙事件捕获

Question

我正在尝试使用广播接收器捕捉蓝牙状态变化。

我的 list :

<uses-permission android:name="android.permission.BLUETOOTH" />
<application>
     <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <receiver android:name=".BluetoothBroadcastReceiver"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.bluetooth.adapter.action.STATE_CHANGED" />
            <action android:name="android.bluetooth.adapter.action.CONNECTION_STATE_CHANGED" />
            <action android:name="android.bluetooth.device.action.ACL_CONNECTED" />
            <action android:name="android.bluetooth.device.action.ACL_DISCONNECTED" />
        </intent-filter>
    </receiver>
</application>

接收者onReceive方法:

public void onReceive(Context context, Intent intent) {

    String action = intent.getAction();
    Log.d("BroadcastActions", "Action "+action+"received");
    int state;
    BluetoothDevice bluetoothDevice;

    switch(action)
    {
        case BluetoothAdapter.ACTION_STATE_CHANGED:
            state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1);
            if (state == BluetoothAdapter.STATE_OFF)
            {
                Toast.makeText(context, "Bluetooth is off", Toast.LENGTH_SHORT).show();
                Log.d("BroadcastActions", "Bluetooth is off");
            }
            else if (state == BluetoothAdapter.STATE_TURNING_OFF)
            {
                Toast.makeText(context, "Bluetooth is turning off", Toast.LENGTH_SHORT).show();
                Log.d("BroadcastActions", "Bluetooth is turning off");
            }
            else if(state == BluetoothAdapter.STATE_ON)
            {
                Log.d("BroadcastActions", "Bluetooth is on");
            }
            break;

        case BluetoothDevice.ACTION_ACL_CONNECTED:
            bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            Toast.makeText(context, "Connected to "+bluetoothDevice.getName(),
                    Toast.LENGTH_SHORT).show();
            Log.d("BroadcastActions", "Connected to "+bluetoothDevice.getName());
            break;

        case BluetoothDevice.ACTION_ACL_DISCONNECTED:
            bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            Toast.makeText(context, "Disconnected from "+bluetoothDevice.getName(),
                    Toast.LENGTH_SHORT).show();
            break;
    }
}

我启动应用程序，然后按主页按钮将其最小化。转到设置并打开蓝牙，但没有任何反应。虽然我期待 toast 和 logcat 消息。这里有什么问题？

Answer 1

为了捕捉蓝牙状态变化(STATE_OFF、STATE_TURNING_ON、STATE_ON、STATE_TURNING_OFF)，请执行以下操作:

首先，在您的 AndroidManifest 文件中添加蓝牙权限:

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

在您的 Activity 或服务中创建一个广播接收器:

    private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();

        if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {
            final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR);
            switch(state) {
                case BluetoothAdapter.STATE_OFF:
                    ..
                    break;
                case BluetoothAdapter.STATE_TURNING_OFF:
                    ..
                    break;
                case BluetoothAdapter.STATE_ON:
                    ..
                    break;
                case BluetoothAdapter.STATE_TURNING_ON:
                    ..
                    break;
            }

        }
    }
};

创建一个 IntentFilter 并将其注册到您的 Activity/Service 的 onCreate() 中的 BroadcastReceiver方法:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    IntentFilter filter1 = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(mBroadcastReceiver1, filter1);
    
    ...
}

在您的 onDestroy() 中取消注册 BroadcastReceiver方法:

@Override
protected void onDestroy() {
    super.onDestroy();

    unregisterReceiver(mBroadcastReceiver1);
}

为了捕捉设备可发现性的变化(SCAN_MODE_NONE、SCAN_MODE_CONNECTABLE、SCAN_MODE_CONNECTABLE_DISCOVERABLE)，如上所述，创建另一个 BroadcastReceiver 并注册/取消注册到您的 Activity。这些广播接收器之间的唯一区别是第一个使用 BluetoothAdapter.EXTRA_STATE另一个使用 BluetoothAdapter.EXTRA_SCAN_MODE .以下是 BroadcastReceiver 捕获可发现性更改的示例代码:

创建一个 IntentFilter 并将其注册到 onCreate()方法:

IntentFilter filter2 = new IntentFilter();
filter2.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter2.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
filter2.addAction(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
registerReceiver(mBroadcastReceiver2, filter2);

在 Activity/Service 中创建 BroadcastReciver 以捕获可发现性更改:

    private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();

        if(action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {

            int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE, BluetoothAdapter.ERROR);

            switch(mode){
                case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
                    ..
                    break;
                case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
                    ..
                    break;
                case BluetoothAdapter.SCAN_MODE_NONE:
                    ..
                    break;
            }
        }
    }
};

最后在 onDestroy() 中注销 BroadcastReciver :

unregisterReceiver(mBroadcastReceiver2);

请注意，您无需添加任何 <intent-filter>或 <receiver>到您的 AndroidManifest 文件中，当然您需要添加蓝牙权限。

如果你想捕捉( ACTION_ACL_CONNECTED ， ACTION_ACL_DISCONNECTED ， ACTION_ACL_DISCONNECT_REQUESTED )，现在你需要添加一个 <intent-filter>到您的 AndroidManifest 文件:

<intent-filter>
    <action android:name="android.bluetooth.device.action.ACL_CONNECTED" />
    <action android:name="android.bluetooth.device.action.ACL_DISCONNECTED" />
</intent-filter>

创建过滤器并将其注册到 onCreate()方法:

IntentFilter filter3 = new IntentFilter();
filter3.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter3.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
registerReceiver(mBroadcastReceiver3, filter3);

然后在您的 Activity/服务中创建广播接收器:

    private final BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        switch (action){
            case BluetoothDevice.ACTION_ACL_CONNECTED:
                ..
                break;
            case BluetoothDevice.ACTION_ACL_DISCONNECTED:
                ..
                break;
        }
    }
};

最后，取消注册:

unregisterReceiver(mBroadcastReceiver3);

如果您想了解有关状态常量的更多信息，请参阅文档:

public static final String EXTRA_STATE:

Used as an int extra field in ACTION_STATE_CHANGED intents to requestthe current power state. Possible values are: STATE_OFF,STATE_TURNING_ON, STATE_ON, STATE_TURNING_OFF

public static final String EXTRA_SCAN_MODE:

Used as an int extra field in ACTION_SCAN_MODE_CHANGED intents torequest the current scan mode. Possible values are: SCAN_MODE_NONE,SCAN_MODE_CONNECTABLE, SCAN_MODE_CONNECTABLE_DISCOVERABLE