如何等到蓝牙在android中打开

Question

我需要以编程方式打开Android设备中的蓝牙并等到它继续进行下一行代码.

我的代码如下

if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                ctx.startActivity(enableBtIntent);
}

当这样做时,代码继续从nect行执行,而不必完全等待蓝牙.有什么方法可以解决这个问题吗？我可以添加外观来检查蓝牙是否已打开？

Answer 1

您可以注册a BroadcastReceiver以监听BluetoothAdapter上的状态更改.

首先创建一个BroadcastReceiver将监听状态变化的人

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

        if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {
            final int bluetoothState = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE,
                                                BluetoothAdapter.ERROR);
            switch (bluetoothState) {
            case BluetoothAdapter.STATE_ON:
                //Bluethooth is on, now you can perform your tasks
                break;
            }
        }
    }
};

于是注册了BroadcastReceiver与你Activity创建时,以便它可以开始接收事件.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //Set a filter to only receive bluetooth state changed events.
    IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(mReceiver, filter);
}

记得在销毁时取消注册监听器Activity.

@Override
public void onDestroy() {
    super.onDestroy();
    unregisterReceiver(mReceiver);
}

Answer 2

您可以在清单文件中使用startActivityForResult()并检查resultCode是否为RESULT_OK并onActivityResult()具有蓝牙权限，例如..

mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (!mBluetoothAdapter.isEnabled()) {
    Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableIntent, 0);
}

活动结果

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode == RESULT_OK){
        // bluetooth enabled                      
    }else{
        // show error
    }       
}

ACTION_REQUEST_ENABLE