Xamarin表单:在一段时间后退出应用程序,检查用户是否处于非活动状态

Question

嗨,我正在尝试使用PCL以xamarin形式构建应用程序.如果应用程序闲置超过10分钟或更长时间,我正尝试从我的应用程序注销用户.我通过在app即将进入睡眠状态时调用的事件来尝试它.但是如果设备screentimeout被设置为永不超时那么也许它永远不会进入睡眠状态.那么我怎样才能做到这一点.我是xamarin表格的新手.当我为所有平台构建应用程序时,我很困惑如何管理此超时？

Answer 1

现在我使用以下方法.可能需要做一些额外的测试,以确保一切按预期工作.例如,我不确定如果应用程序(iOS或Android)在后台工作了很长时间会发生什么.定时器是否仍会每秒调用一次？也许当使用具有足够短的到期时间(约5分钟)的计时器时,这不是问题吗？等等...

我的方法基于我在网上找到的几段代码(一些Xamarin代码,一些Swift/Java代码) - 似乎没有一个很好的综合解决方案.

无论如何,一些初步测试表明这种方法工作正常.

首先,我创建了一个名为的单例类SessionManager.这个类包含一个计时器(实际上只是一个每秒睡眠的while循环)以及启动,停止和扩展计时器的方法.如果会话到期计时器到期,它还将触发事件.

public sealed class SessionManager
{
    static readonly Lazy<SessionManager> lazy =
        new Lazy<SessionManager>(() => new SessionManager());

    public static SessionManager Instance { get { return lazy.Value; } }

    SessionManager() { 
        this.SessionDuration = TimeSpan.FromMinutes(5);
        this.sessionExpirationTime = DateTime.FromFileTimeUtc(0);
    }

    /// <summary>
    /// The duration of the session, by default this is set to 5 minutes.
    /// </summary>
    public TimeSpan SessionDuration;

    /// <summary>
    /// The OnSessionExpired event is fired when the session timer expires.
    /// This event is not fired if the timer is stopped manually using 
    /// EndTrackSession.
    /// </summary>
    public EventHandler OnSessionExpired;

    /// <summary>
    /// The session expiration time.
    /// </summary>
    DateTime sessionExpirationTime;

    /// <summary>
    /// A boolean value indicating wheter a session is currently active.
    /// Is set to true when StartTrackSessionIsCalled. Becomes false if 
    /// the session is expired manually or by expiration of the session 
    /// timer.
    /// </summary>
    public bool IsSessionActive { private set; get; }

    /// <summary>
    /// Starts the session timer.
    /// </summary>
    /// <returns>The track session async.</returns>
    public async Task StartTrackSessionAsync() {
        this.IsSessionActive = true;

        ExtendSession();

        await StartSessionTimerAsync();
    }

    /// <summary>
    /// Stop tracking a session manually. The OnSessionExpired will not be 
    /// called.
    /// </summary>
    public void EndTrackSession() {
        this.IsSessionActive = false;

        this.sessionExpirationTime = DateTime.FromFileTimeUtc(0);
    }

    /// <summary>
    /// If the session is active, then the session time is extended based 
    /// on the current time and the SessionDuration.
    /// duration.
    /// </summary>
    public void ExtendSession()
    {
        if (this.IsSessionActive == false) {
            return;
        }

        this.sessionExpirationTime = DateTime.Now.Add(this.SessionDuration);
    }

    /// <summary>
    /// Starts the session timer. When the session is expired and still 
    /// active the OnSessionExpired event is fired. 
    /// </summary>
    /// <returns>The session timer async.</returns>
    async Task StartSessionTimerAsync() {
        if (this.IsSessionActive == false) {
            return;
        }

        while (DateTime.Now < this.sessionExpirationTime) {
            await Task.Delay(1000);                
        }

        if (this.IsSessionActive && this.OnSessionExpired != null) {
            this.IsSessionActive = false;

            this.OnSessionExpired.Invoke(this, null);
        }
    }
}

对于Android应用程序,我然后:

• 配置SessionManagerMainActivity中的会话到期时注销.

• 覆盖该OnUserInteraction方法以MainActivity在用户交互上扩展会话计时器.

  public class MainActivity /* ... */ {
      protected override void OnCreate(Bundle bundle)
      {   
          // ...
  
          SessionManager.Instance.SessionDuration = TimeSpan.FromSeconds(10);
          SessionManager.Instance.OnSessionExpired = HandleSessionExpired;
      }
  
      public override void OnUserInteraction()
      {
          base.OnUserInteraction();
  
          SessionManager.Instance.ExtendSession();
      }
  
      async void HandleSessionExpired(object sender, EventArgs e)
      {
          await App.Instance.DoLogoutAsync();
      }    
  }
  

对于iOS,我执行以下操作:

• SessionManager在会话到期时配置AppDelegate中的注销.

• 向关键窗口添加自定义手势处理程序,以扩展用户交互的会话计时器.

  public partial class AppDelegate /* ... */
  {
      public override bool FinishedLaunching(UIApplication app, NSDictionary options)
      {
          // ...
  
          var success = base.FinishedLaunching(app, options);
  
          if (success) {
              SessionManager.Instance.SessionDuration = TimeSpan.FromSeconds(10);
              SessionManager.Instance.OnSessionExpired += HandleSessionExpired;
  
              var allGesturesRecognizer = new AllGesturesRecognizer(delegate
              {
                  SessionManager.Instance.ExtendSession();
              });
  
              this.Window.AddGestureRecognizer(allGesturesRecognizer);
          }
  
          return success;
      }
  
      async void HandleSessionExpired(object sender, EventArgs e)
      {
          await App.instance.DoLogoutAsync();
      }
  
      class AllGesturesRecognizer: UIGestureRecognizer {
          public delegate void OnTouchesEnded();
  
          private OnTouchesEnded touchesEndedDelegate;
  
          public AllGesturesRecognizer(OnTouchesEnded touchesEnded) {
              this.touchesEndedDelegate = touchesEnded;
          }
  
          public override void TouchesEnded(NSSet touches, UIEvent evt)
          {
              this.State = UIGestureRecognizerState.Failed;
  
              this.touchesEndedDelegate();
  
              base.TouchesEnded(touches, evt);
          }
      }
  }
  

编辑:博洛在下面问了一个很好的问题,所以我会在这里添加.用户登录后立即调用StartTrackSessionAsync.当用户退出应用程序时,应调用EndTrackSession.

Answer 2

调整了@Wolfgang 版本

public sealed class SessionManager
{
    static readonly Lazy<SessionManager> lazy =
        new Lazy<SessionManager>(() => new SessionManager());

    public static SessionManager Instance { get { return lazy.Value; } }
    private Stopwatch StopWatch = new Stopwatch();

    SessionManager()
    {
        SessionDuration = TimeSpan.FromMinutes(5);
    }

    public TimeSpan SessionDuration;

    public void EndTrackSession()
    {
        if (StopWatch.IsRunning)
        {
            StopWatch.Stop();
        }
    }

    public void ExtendSession()
    {
        if (StopWatch.IsRunning)
        {
            StopWatch.Restart();
        }
    }

    public void StartTrackSessionAsync()
    {
        if (!StopWatch.IsRunning)
        {
            StopWatch.Restart();
        }

        Xamarin.Forms.Device.StartTimer(new TimeSpan(0, 0, 2), () =>
        {
            if (StopWatch.IsRunning && StopWatch.Elapsed.Minutes >= SessionDuration.Minutes)
            {
                Xamarin.Forms.Device.BeginInvokeOnMainThread(async () =>
                {
                    await Prism.PrismApplicationBase.Current.Container.Resolve<INavigationService>().NavigateAsync("/Index/Navigation/LoginPage");
                });

                StopWatch.Stop();
            }

            return true;
        });

    }

}

在主要活动下添加了以下内容

    public override void OnUserInteraction()
    {
        base.OnUserInteraction();
        SessionManager.Instance.ExtendSession();
    }

Answer 3

不幸的是，这并不是您可以在客户端轻松完成的事情。也没有办法仅通过 PCL 来完成此操作。可能有一个插件可以添加到您的项目中，但我还没有找到。

造成这种情况的原因是 iOS 和 Android 处理应用程序生命周期的方式不同。两者非常不同。例如，一旦 iOS 挂起您的应用程序，实际上只有 2 种方法可以唤醒它。GPS 位置更新和推送通知。在 Android 中，这更容易，因为他们有 AlarmManager，您可以注册并意图为您执行注销。

我的建议是，如果您控制正在使用的 api，请让会话在服务器端过期，这样 10 分钟后传入的任何请求都会失败，并在客户端适当处理这些失败。

如果您纯粹关心应用程序何时位于前台且处于活动状态但未使用，则您将必须实现一个计时器，并在每次有用户交互时重置它。