C# 吐司不止一次被展示

我正在为Android开发一款QR阅读器应用程序。该应用程序的要点是使用手机摄像头读取二维码。如果用户未使用应用程序，则相机会在特定时间后停止（使用

计时器进行此操作），以防止电池消耗并使手机振动，并显示一个祝酒词，其中包含一条消息，指示用户按下按钮重新激活相机，然后继续他的工作

问题是，当事件第一次被触发时，一切都如我所期望的那样工作，但是如果它再次被触发，则Toast将显示两次，如果事件被触发N次，则以此类推

此解决方案背后的逻辑如下：

“恢复”相机功能的按钮逻辑：

btnEncenderCamara.Click += (sender, e) => {
            camara.Start(lectorQR.Holder);
            btnEncenderCamara.Enabled = false;
            timerToDisableCamera.Interval = 6000;
            timerToDisableCamera.Elapsed += new ElapsedEventHandler(timerElapsed);
            timerToDisableCamera.Start();
        };

以及计时器的事件逻辑：

protected void timerElapsed(object sender, ElapsedEventArgs e) {
        try
        {
            timerToDisableCamera.Stop();
            RunOnUiThread(() => {
                Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
                vibrator.Vibrate(1000);
                camara.Stop();
                btnEncenderCamara.Enabled = true;
                Toast.MakeText(this, "La cámara se ha detenido para ahorrar en cosumo de batería. Presione 'ENCENDER CÁMARA' para encender la cámara nuevamente", ToastLength.Short).Show();
            });
        }
        catch (Exception ex)
        {

            throw;
        }
    }

我需要找到如何避免在触发停止相机的事件后多次显示Toast。
请注意，在您的btnEncenderCamara.Click事件中，您正在向timerToDisableCamera.Appeased事件订阅一个新的委托，每次触发btnEncenderCamara.Click

因此，每次后续调用btnEncenderCamara.Click时，都会多次调用TimeRecursed方法

解决此问题的一种方法是，在调用timerToDisableCamera.Stop（）后，在TimeRecursed方法中取消订阅代理，如下所示：

protected void timerElapsed(object sender, ElapsedEventArgs e) {
        try
        {
            timerToDisableCamera.Stop();

            timerToDisableCamera.Elapsed -= new ElapsedEventHandler(timerElapsed);

            RunOnUiThread(() => {
                Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
                vibrator.Vibrate(1000);
                camara.Stop();
                btnEncenderCamara.Enabled = true;
                Toast.MakeText(this, "La cámara se ha detenido para ahorrar en cosumo de batería. Presione 'ENCENDER CÁMARA' para encender la cámara nuevamente", ToastLength.Short).Show();
            });
        }
        catch (Exception ex)
        {

            throw;
        }
    }

// I'm assuming this method is an entry point for initialization in your Android activity.
void OnLoad()
{
    // I'm assuming timerToDisableCamera already have an instance of Timer, otherwise you will get a NullReferenceException.
    timerToDisableCamera.Interval = 6000;
    timerToDisableCamera.Elapsed += new ElapsedEventHandler(timerElapsed);

    // And also assuming that btnEncenderCamara is already an instance of Button.
    btnEncenderCamara.Click += (sender, e) => {
        camara.Start(lectorQR.Holder);
        btnEncenderCamara.Enabled = false;
        timerToDisableCamera.Start();
    };
}

protected void timerElapsed(object sender, ElapsedEventArgs e)
{
    try
    {
        timerToDisableCamera.Stop();

        RunOnUiThread(() => {
            Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
            vibrator.Vibrate(1000);
            camara.Stop();
            btnEncenderCamara.Enabled = true;
            Toast.MakeText(this, "La cámara se ha detenido para ahorrar en cosumo de batería. Presione 'ENCENDER CÁMARA' para encender la cámara nuevamente", ToastLength.Short).Show();
        });
    }
    catch (Exception ex)
    {
        throw;
    }
}

或者，您可以重构代码，只初始化计时器一次，这将保持逻辑精简，如下所示：

protected void timerElapsed(object sender, ElapsedEventArgs e) {
        try
        {
            timerToDisableCamera.Stop();

            timerToDisableCamera.Elapsed -= new ElapsedEventHandler(timerElapsed);

            RunOnUiThread(() => {
                Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
                vibrator.Vibrate(1000);
                camara.Stop();
                btnEncenderCamara.Enabled = true;
                Toast.MakeText(this, "La cámara se ha detenido para ahorrar en cosumo de batería. Presione 'ENCENDER CÁMARA' para encender la cámara nuevamente", ToastLength.Short).Show();
            });
        }
        catch (Exception ex)
        {

            throw;
        }
    }

// I'm assuming this method is an entry point for initialization in your Android activity.
void OnLoad()
{
    // I'm assuming timerToDisableCamera already have an instance of Timer, otherwise you will get a NullReferenceException.
    timerToDisableCamera.Interval = 6000;
    timerToDisableCamera.Elapsed += new ElapsedEventHandler(timerElapsed);

    // And also assuming that btnEncenderCamara is already an instance of Button.
    btnEncenderCamara.Click += (sender, e) => {
        camara.Start(lectorQR.Holder);
        btnEncenderCamara.Enabled = false;
        timerToDisableCamera.Start();
    };
}

protected void timerElapsed(object sender, ElapsedEventArgs e)
{
    try
    {
        timerToDisableCamera.Stop();

        RunOnUiThread(() => {
            Vibrator vibrator = (Vibrator)GetSystemService(Context.VibratorService);
            vibrator.Vibrate(1000);
            camara.Stop();
            btnEncenderCamara.Enabled = true;
            Toast.MakeText(this, "La cámara se ha detenido para ahorrar en cosumo de batería. Presione 'ENCENDER CÁMARA' para encender la cámara nuevamente", ToastLength.Short).Show();
        });
    }
    catch (Exception ex)
    {
        throw;
    }
}

谢谢你花时间阅读我的帖子。我假设我可以将“OnLoad”方法的行添加到“OnCreate”方法中，该方法触发我的活动，使用手机摄像头只创建一次计时器。我会测试一下，然后告诉你发生了什么。再次感谢您的回复和时间。我已经重构了我的代码，就像您在我的“OnCreate”方法上发布的一样，它可以工作：）所以感谢您的回复。我会把你的回答作为我问题的答案。很高兴能帮上忙：-）