Android端ScheduledAlarmHandler触发System.ArgumentNullException崩溃求助

应用在Google Play Store出现大量崩溃，无法定位来源及复现方式，推测崩溃发生在应用处于后台（或已被杀死）且触发本地通知时，堆栈追踪指向ScheduledAlarmHandler。

崩溃堆栈信息 #

Exception android.runtime.JavaProxyThrowable: System.ArgumentNullException: Value cannot be null. Parameter name: s  at System.IO.StringReader..ctor (System.String s) [0x00009] in <2f4adfad501c4e4abfe6a9b300c1b849>:0    at (wrapper remoting-invoke-with-check) System.IO.StringReader..ctor(string)   at LocalNotifications.Plugin.ScheduledAlarmHandler.serializeFromString (System.String notificationString) [0x00010] in <42e60f59bb2b4f93942a1c96f54643af>:0    at LocalNotifications.Plugin.ScheduledAlarmHandler.OnReceive (Android.Content.Context context, Android.Content.Intent intent) [0x0000c] in <42e60f59bb2b4f93942a1c96f54643af>:0    at Android.Content.BroadcastReceiver.n_OnReceive_Landroid_content_Context_Landroid_content_Intent_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_context, System.IntPtr native_intent) [0x00017] in <1eada6631e384353908e0dab9d072f35>:0    at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPLL_V (_JniMarshal_PPLL_V callback, System.IntPtr jnienv, System.IntPtr klazz, System.IntPtr p0, System.IntPtr p1) [0x00005] in <1eada6631e384353908e0dab9d072f35>:0    at crc6449389a0f4059adff.ScheduledAlarmHandler.n_onReceive   at crc6449389a0f4059adff.ScheduledAlarmHandler.onReceive (ScheduledAlarmHandler.java:30)   at android.app.ActivityThread.handleReceiver (ActivityThread.java:4497)   at android.app.ActivityThread.access$1600 (ActivityThread.java:301)   at android.app.ActivityThread$H.handleMessage (ActivityThread.java:2188)   at android.os.Handler.dispatchMessage (Handler.java:106)   at android.os.Looper.loop (Looper.java:246)   at android.app.ActivityThread.main (ActivityThread.java:8653)   at java.lang.reflect.Method.invoke   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:602)   at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1130)

已尝试的方案 #

在OnReceive方法外层包裹PowerManager.WakeLock，但未解决崩溃问题。

相关代码 #

[BroadcastReceiver(Enabled = true, Exported = true)]
[IntentFilter(new[] { Android.Content.Intent.ActionBootCompleted })]

public class ScheduledAlarmHandler : BroadcastReceiver
{ 
    public const string LocalNotificationKeyText = "LocalNotification_TEXT";
    public const string LocalNotificationKeyID = "LocalNotification_ID";
    public const string LocalNotificationKeyTitle = "LocalNotification_TITLE";
    public NotificationManager manager;
    
    public override void OnReceive(Context context, Intent intent)
    {
        if (context != null)
        {
            PowerManager pm = (PowerManager)context.GetSystemService(Context.PowerService);
            PowerManager.WakeLock wakeLock = pm.NewWakeLock(WakeLockFlags.Partial, "ScheduledAlarmHandler");
            wakeLock.Acquire();
            
            var id = intent.GetIntExtra(LocalNotificationKeyID, 0);
            var title = intent.GetStringExtra(LocalNotificationKeyTitle);
            var text = intent.GetStringExtra(LocalNotificationKeyText);

            var notification = new LocalNotification();
            notification.Title = title;
            notification.Text = text;
            notification.Id = id;

            manager = getNotificationManager();
            var nativeNotification = createNativeNotification(context, notification);

            if (notification.Id == 909092)
            {
                //Remove ongoing notification that you have an active session
                manager.Cancel(909093);
            }
            manager.Notify(notification.Id, nativeNotification);
            wakeLock.Release();
        }
    }

    private NotificationManager getNotificationManager()
    {
        var notificationManager = Application.Context.GetSystemService(Context.NotificationService) as NotificationManager;
        return notificationManager;
    }
}

排查思路与解决建议 #

• 定位空值根源：从堆栈看，崩溃是因为serializeFromString方法传入的字符串参数为null，导致StringReader初始化失败。需检查：
  • 设置定时通知时，是否确保传递给Intent的LocalNotification_TITLE、LocalNotification_TEXT等参数无空值；
  • 应用被系统杀死后，Intent是否被系统重建导致部分Extra丢失。
• 强化空值校验：在OnReceive中增加多层空值判断，避免后续逻辑因空值崩溃：

  if (intent == null || !intent.HasExtra(LocalNotificationKeyID) || 
      string.IsNullOrEmpty(intent.GetStringExtra(LocalNotificationKeyTitle)) || 
      string.IsNullOrEmpty(intent.GetStringExtra(LocalNotificationKeyText)))
  {
      wakeLock?.Release();
      return;
  }
  

• 修复NotificationManager获取逻辑：避免使用Application.Context（应用被杀后可能为空），改用传入的context获取服务：

  private NotificationManager getNotificationManager(Context context)
  {
      return context.GetSystemService(Context.NotificationService) as NotificationManager;
  }
  

  调用时传入context：manager = getNotificationManager(context);
• 安全处理WakeLock：使用空值运算符确保Release不会触发空指针异常，改为wakeLock?.Release();
• 复现测试：在应用后台、进程被杀状态下触发定时通知，通过Logcat查看实时日志，或结合Crashlytics查看崩溃设备的型号、Android版本分布，排查是否存在机型适配问题。
• 检查插件版本：若使用第三方LocalNotifications插件，查看是否有新版本修复了空值相关Bug，或检索插件的Issue列表是否有同类问题。

内容的提问来源于stack exchange，提问作者Spire