如何在Xamarin Android中实现本地推送通知

Question

我正在使用Xamarin.Forms应用程序。我想为Android平台实现本地推送通知，只要最小化应用程序或锁定手机，应用程序就可以通过该通知接收通知。我也想唤醒手机，并在手机锁定时在锁定屏幕上显示通知。

由于我是新来的，请帮助我。

提前感谢。

Vivek

Answer 1

您需要的是推送通知，而不是本地通知。仅当您的应用程序正在运行时，本地通知才起作用。推送通知由操作系统（在这种情况下为Android）处理。 Xamarin建议使用Firebase服务来处理它。程序很简单，您所要做的就是按照Xamarin官方网站上的教程进行操作。

Remote Notifications with Firebase Cloud Messaging

Answer 2

我认为您应该考虑两件事。

1。听屏幕锁定：

创建ScreenListener.cs：

public class ScreenListener
{
    private Context mContext;
    private ScreenBroadcastReceiver mScreenReceiver;
    private static ScreenStateListener mScreenStateListener;

    public ScreenListener(Context context)
    {
        mContext = context;
        mScreenReceiver = new ScreenBroadcastReceiver();
    }

    /**
     * screen BroadcastReceiver
     */
    private class ScreenBroadcastReceiver : BroadcastReceiver
    {
    private String action = null;

        public override void OnReceive(Context context, Intent intent)
        {
            action = intent.Action;
            if (Intent.ActionScreenOn == action)
            { // screen on
                mScreenStateListener.onScreenOn();
            }
            else if (Intent.ActionScreenOff == action)
            { // screen off
                mScreenStateListener.onScreenOff();
            }
            else if (Intent.ActionUserPresent == action)
            { // unlock
                mScreenStateListener.onUserPresent();
            }
        }
    }

/**
 * begin to listen screen state
 *
 * @param listener
 */
public void begin(ScreenStateListener listener)
{
    mScreenStateListener = listener;
    registerListener();
    getScreenState();
}

/**
 * get screen state
 */
private void getScreenState()
{
    PowerManager manager = (PowerManager)mContext
            .GetSystemService(Context.PowerService);
    if (manager.IsScreenOn)
    {
        if (mScreenStateListener != null)
        {
            mScreenStateListener.onScreenOn();
        }
    }
    else
    {
        if (mScreenStateListener != null)
        {
            mScreenStateListener.onScreenOff();
        }
    }
}

/**
 * stop listen screen state
 */
public void unregisterListener()
{
    mContext.UnregisterReceiver(mScreenReceiver);
}

/**
 * regist screen state broadcast
 */
private void registerListener()
{
    IntentFilter filter = new IntentFilter();
    filter.AddAction(Intent.ActionScreenOn);
    filter.AddAction(Intent.ActionScreenOff);
    filter.AddAction(Intent.ActionUserPresent);
    mContext.RegisterReceiver(mScreenReceiver, filter);
}

public interface ScreenStateListener
{// Returns screen status information to the caller
    void onScreenOn();

    void onScreenOff();

    void onUserPresent();
}
}

然后在MainActivity.cs：

中

public class MainActivity : AppCompatActivity,ScreenStateListener
{
   ScreenListener mScreenListener;
   protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.activity_main);
        mScreenListener = new ScreenListener(this);
    }
   protected override void OnDestroy()
    {
        base.OnDestroy();
        mScreenListener.unregisterListener();
    }

   protected override void OnResume()
    {
        base.OnResume();
        mScreenListener.begin(this);

    }
   public void onScreenOn()
    {
        Console.WriteLine("onScreenOn");
    }

   public void onScreenOff()
    {
        Console.WriteLine("onScreenOff");
    }

   public void onUserPresent()
    {
        Console.WriteLine("onUserPresent");
    }


}

2.creat loacal Notification：

最后，您只需按onScreenOff()方法推送通知。