如何等到蓝牙在android中打开

首先创建一个将侦听状态更改的BroadcastReceiver

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;
            }
        }
    }
};

然后在创建时使用您的Activity注册BroadcastReceiver,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);
}

记住在销毁Activity时取消注册侦听器.

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