Xamrin.Forms android端全局异常处理

以下为MainActivity中代码

using System;

using Android.App;
using Android.Content.PM;
using Android.Runtime;
using Android.OS;
using XamrinScanner.Services;
using Android.Content;
using System.Threading.Tasks;
using System.IO;
using Environment = System.Environment;
using System.Diagnostics;

namespace XamrinScanner.Droid
{
    [Activity(Label = "XamrinScanner", Icon = "@mipmap/shoujisaoma", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize )]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        public static Context AppContext;
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            //unhander excption event 
            AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;
            TaskScheduler.UnobservedTaskException += TaskSchedulerOnUnobservedTaskException;

            global::Xamarin.Forms.Forms.SetFlags("FastRenderers_Experimental");
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            AiForms.Dialogs.Dialogs.Init(this); //need to write here

            AppContext = ApplicationContext;

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            App.TodoManager = new TodoManager(new SoapService());
            //App.TodoManager = new TodoManager();
            LoadApplication(new App());
        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }





        //global exception handling
        //link https://peterno.wordpress.com/2015/04/15/unhandled-exception-handling-in-ios-and-android-with-xamarin/

        #region Error handling
        private static void TaskSchedulerOnUnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs unobservedTaskExceptionEventArgs)
        {
            var newExc = new Exception("TaskSchedulerOnUnobservedTaskException", unobservedTaskExceptionEventArgs.Exception);
            LogUnhandledException(newExc);
        }

        private static void CurrentDomainOnUnhandledException(object sender, UnhandledExceptionEventArgs unhandledExceptionEventArgs)
        {
            var newExc = new Exception("CurrentDomainOnUnhandledException", unhandledExceptionEventArgs.ExceptionObject as Exception);
            LogUnhandledException(newExc);
        }

        internal static void LogUnhandledException(Exception exception)
        {
            try
            {
                const string errorFileName = "Fatal.log";
                var libraryPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal); // iOS: Environment.SpecialFolder.Resources
                var errorFilePath = Path.Combine(libraryPath, errorFileName);
                var errorMessage = String.Format("Time: {0}\r\nError: Unhandled Exception\r\n{1}",
                DateTime.Now, exception.ToString());
                File.WriteAllText(errorFilePath, errorMessage);

                // Log to Android Device Logging.
                Android.Util.Log.Error("Crash Report", errorMessage);
            }
            catch
            {
                // just suppress any error logging exceptions
            }
        }

        /// <summary>
        // If there is an unhandled exception, the exception information is diplayed 
        // on screen the next time the app is started (only in debug configuration)
        /// </summary>
        [Conditional("DEBUG")]
        private void DisplayCrashReport()
        {
            const string errorFilename = "Fatal.log";
            var libraryPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
            var errorFilePath = Path.Combine(libraryPath, errorFilename);

            if (!File.Exists(errorFilePath))
            {
                return;
            }

            var errorText = File.ReadAllText(errorFilePath);
            new AlertDialog.Builder(this)
                .SetPositiveButton("Clear", (sender, args) =>
                {
                    File.Delete(errorFilePath);
                })
                .SetNegativeButton("Close", (sender, args) =>
                {
                // User pressed Close.
            })
                .SetMessage(errorText)
                .SetTitle("Crash Report")
                .Show();
        }

        #endregion

    }





}