在Android上，我可以注册一个回调，告诉我如果蓝牙开启或关闭？ [英] On Android, can I register for a callback that tells me if Bluetooth is turned on or off?

问题描述

我需要知道我的应用程序内的蓝牙是否开启或关闭。或者如果蓝牙被接通或关断例如从操作系统设置下拉菜单。我以为我可以在活动的做到这一点onResume（）。但事实证明，Android操作系统的设置下拉菜单（即拉下从屏幕顶部边缘的手指访问的一种）打开时该活动不会暂停。

I need to know inside my app whether bluetooth is on or off. Or if bluetooth was turned on or off e.g. from the OS settings pulldown menu. I thought I could do this in the Activity's onResume(). But it turns out that the activity is not paused when the Android OS's settings "pulldown menu" (the one that is accessed by pulling down with a finger from the top edge of the screen) is opened.

我需要在蓝牙变为可用或不可更新我的UI。

I need to update my UI when bluetooth becomes available or unavailable.

我可以注册一个回调（例如广播接收器）或任何其它的回调，让系统告诉我，当蓝牙可用性的变化？

Can I register for a callback (e.g. a BroadcastReceiver) or any other callback to let the system tell me when Bluetooth availability changes?

推荐答案

您可以接收与意图过滤器进行注册：

You can register the receiver with intent filter:

<receiver
        android:name="com.example.BluetoothReceiver"
        android:enabled="true">
    <intent-filter>
        <action android:name="android.bluetooth.adapter.action.STATE_CHANGED"/>
    </intent-filter>
</receiver>

这是广播接收器：

And this is the BroadcastReceiver:

public class BluetoothReceiver extends BroadcastReceiver {

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

        if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
            int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1);

            switch (state){
                case BluetoothAdapter.STATE_OFF:
                    //Indicates the local Bluetooth adapter is off.
                break;

                case BluetoothAdapter.STATE_TURNING_ON:
                    //Indicates the local Bluetooth adapter is turning on. However local clients should wait for STATE_ON before attempting to use the adapter.
                break;

                case BluetoothAdapter.STATE_ON:
                    //Indicates the local Bluetooth adapter is on, and ready for use.
                break;

                case BluetoothAdapter.STATE_TURNING_OFF:
                    //Indicates the local Bluetooth adapter is turning off. Local clients should immediately attempt graceful disconnection of any remote links.
                break;
            }
        }
    }
};

或者，如果你想直接在活动中加入：

Or if you want to add directly in the activity:

public class ExampleActivity extends AppCompatActivity {

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

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(mReceiver, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
    }

    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(mReceiver);
    }

    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {

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

            if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
                int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1);

                switch (state) {
                    case BluetoothAdapter.STATE_OFF:
                        //Indicates the local Bluetooth adapter is off.
                        break;

                    case BluetoothAdapter.STATE_TURNING_ON:
                        //Indicates the local Bluetooth adapter is turning on. However local clients should wait for STATE_ON before attempting to use the adapter.
                        break;

                    case BluetoothAdapter.STATE_ON:
                        //Indicates the local Bluetooth adapter is on, and ready for use.
                        break;

                    case BluetoothAdapter.STATE_TURNING_OFF:
                        //Indicates the local Bluetooth adapter is turning off. Local clients should immediately attempt graceful disconnection of any remote links.
                        break;
                }
            }
        }
    };
}

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