如何在Android上通过电源按钮自动启动app页面

Question

我在VS 2017中使用Xamarin Android为我的侄女制作了一个小应用程序。我希望它在应用程序上打开一个页面，在她每次打开手机时都会问她一个简单的乘法问题。我希望它作为前台服务运行，这样当应用程序最小化时，它仍然可以运行。我有一个广播接收器，当应用程序有焦点时，它会检测到按钮事件，我已经将其移动到服务上运行。

目前，我按下切换按钮，然后5-10秒后，它抛出一个错误。看不到VS中的错误，因为它是外部的。我猜那是Genymotion模拟器捕捉到的吧？

有什么想法吗？

更新:我想我会来更新这篇文章，如果它对其他人有任何用处的话。在Oreo更新之后，NotificationCompat.Builder现在需要提供通道ID。我已经在代码中反映了这一点，它现在可以正确地启动服务。

我仍然需要让广播接收器从服务中工作，但我已经做到了！

更新2:任务完成！

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
    Intent startServiceIntent;
    Intent stopServiceIntent;

    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.activity_main);

        // Difficulty Radio Buttons
        RadioButton radioEasy = FindViewById<RadioButton>(Resource.Id.radioEasy);
        radioEasy.Click += RadioButton_Click;
        RadioButton radioMedium = FindViewById<RadioButton>(Resource.Id.radioMedium);
        radioMedium.Click += RadioButton_Click;
        RadioButton radioHard = FindViewById<RadioButton>(Resource.Id.radioHard);
        radioHard.Click += RadioButton_Click;

        // Set/Remove Lock
        Button ToggleLock = FindViewById<Button>(Resource.Id.ToggleLock);
        ToggleLock.Click += ToggleLock_Click;

        startServiceIntent = new Intent(this, typeof(LockService));
        stopServiceIntent = new Intent(this, typeof(LockService));
    }

    private void RadioButton_Click(object sender, EventArgs e)
    {
        var radiobtn = sender as RadioButton;
        Toast.MakeText(this, radiobtn.Text, ToastLength.Long).Show();
    }
    private void ToggleLock_Click(object sender, EventArgs e)
    {
        var togglebtn = sender as ToggleButton;
        if (togglebtn.Checked)
        {
            if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
                StartForegroundService(startServiceIntent);
            else
                StartService(startServiceIntent);

            Toast.MakeText(this, "On", ToastLength.Long).Show();
        }
        else
        {
            Toast.MakeText(this, "Off", ToastLength.Long).Show();
        }
    }
}


/// <summary>
/// ////////////////////////////////////////////////////////////////////////////
/// </summary>

[Service]
public class LockService : Service
{
    private PowerBroadcastReceiver receiver;

    public override void OnCreate()
    {
    }

    public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
    {
        NotificationManager mngr = (NotificationManager)GetSystemService(NotificationService);
        NotificationChannel chnl = new NotificationChannel("Channel", "Name", NotificationImportance.Default);
        mngr.CreateNotificationChannel(chnl);

        NotificationCompat.Builder foregroundNotification = new NotificationCompat.Builder(this);
        foregroundNotification.SetOngoing(true);
        foregroundNotification.SetContentTitle("My Foreground Notification")
                .SetChannelId("Channel")
                .SetContentText("This is the first foreground notification Peace");

        StartForeground(101, foregroundNotification.Notification);

        // Broadcast Receiver
        receiver = new PowerBroadcastReceiver();
        RegisterReceiver(receiver, new IntentFilter(Intent.ActionScreenOn));

        return StartCommandResult.Sticky;
    }

    public override IBinder OnBind(Intent intent)
    {
        // Return null because this is a pure started service. A hybrid service would return a binder that would
        // allow access to the GetFormattedStamp() method.
        return null;
    }

}

/// <summary>
/// ////////////////////////////////////////////////////////////////////////////////
/// </summary>

[BroadcastReceiver]
[IntentFilter(new[] { Intent.ActionScreenOn, Intent.ActionScreenOff })]
public class PowerBroadcastReceiver : BroadcastReceiver
{
    public PowerBroadcastReceiver()
    {
    }

    public override void OnReceive(Context context, Intent intent)
    {
        if (intent.Action.Equals(Intent.ActionScreenOn))
        {
            // TODO: Launch Question Page

            Toast.MakeText(context, "On", ToastLength.Long).Show();
        }
        else if (intent.Action.Equals(Intent.ActionScreenOff))
            Toast.MakeText(context, "Off", ToastLength.Long).Show();
    }
}

谢谢。

Answer 1

你可以创建一个监听类来监听android的锁屏和解锁事件，使用广播来接收屏幕的状态。因为是系统广播，所以我不认为有必要使用Service。

你可以参考这个：https://stackoverflow.com/a/55014763/10768653