Question

我的Android应用程序（使用Xamarin.Forms创建）在真实设备（华硕Zenfone 2）上启动（在调试和发布模式下）大约需要10秒钟。启动画面显示8秒钟。这是我的日志，其中“extrony”是我的应用名称。只有装配加载需要很长时间。有什么帮助吗？

Android Startup log

编辑1： 它实际上需要10秒钟（我错误地提到了8个，但现在更新了）

编辑2：在模拟器上（我在Visual Studio中使用Android模拟器）应用程序启动速度更快，即在4.3秒内。但是在我的真实设备（华硕Zenfone2）上，所需的时间是10秒。在真实设备上进行调试时，我在调试输出上看到的另外一件事（如果在模拟器上调试则不会出现）并且加载这些组件ALONE需要大约6秒。

Android application is debugging.
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.Droid.dll
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.Support.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.UserDialogs.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Acr.UserDialogs.Interface.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/AndHUD.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/CarouselView.FormsPlugin.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/CarouselView.FormsPlugin.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Forms.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Forms.Droid.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FFImageLoading.Platform.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/FormsViewGroup.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/HtmlAgilityPack.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Analytics.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Analytics.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Crashes.Android.Bindings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.Crashes.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Azure.Mobile.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Data.Sqlite.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.Relational.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.EntityFrameworkCore.Sqlite.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Caching.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Caching.Memory.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.DependencyInjection.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.DependencyInjection.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Logging.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Logging.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Options.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Microsoft.Extensions.Primitives.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/ModernHttpClient.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Newtonsoft.Json.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/OkHttp.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Connectivity.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Connectivity.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.CurrentActivity.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Settings.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Settings.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Share.Abstractions.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Plugin.Share.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Remotion.Linq.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/SgmlReaderDll.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Splat.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Collections.Immutable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Diagnostics.DiagnosticSource.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Interactive.Async.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/System.Runtime.CompilerServices.Unsafe.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Animated.Vector.Drawable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.CustomTabs.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Design.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v4.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.AppCompat.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.CardView.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.MediaRouter.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.v7.RecyclerView.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Android.Support.Vector.Drawable.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Core.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Platform.Android.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Platform.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/Xamarin.Forms.Xaml.dll [External]
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.dll
Loaded assembly: /storage/emulated/0/Android/data/com.abdullah.extrony/files/.__override__/extrony.Data.dll
Loaded assembly: Mono.Android.dll [External]
Loaded assembly: Java.Interop.dll [External]
Loaded assembly: System.Runtime.dll [External]
Loaded assembly: System.Collections.Concurrent.dll [External]
Loaded assembly: System.Reflection.dll [External]
Loaded assembly: System.Threading.dll [External]
Loaded assembly: System.Diagnostics.Debug.dll [External]
Loaded assembly: System.dll [External]
Loaded assembly: System.Runtime.InteropServices.dll [External]
Loaded assembly: System.Collections.dll [External]
Loaded assembly: System.Linq.dll [External]
Loaded assembly: System.Core.dll [External]
Loaded assembly: System.Reflection.Extensions.dll [External]
Loaded assembly: MonoDroidConstructors [External]
Loaded assembly: System.ObjectModel.dll [External]
Loaded assembly: System.Threading.Tasks.dll [External]
Loaded assembly: System.Xml.ReaderWriter.dll [External]
Loaded assembly: System.Xml.dll [External]
Loaded assembly: System.IO.dll [External]
Loaded assembly: System.Runtime.Extensions.dll [External]
Loaded assembly: System.Linq.Expressions.dll [External]
Loaded assembly: System.Resources.ResourceManager.dll [External]
Loaded assembly: System.Globalization.dll [External]
Loaded assembly: System.Dynamic.Runtime.dll [External]
Loaded assembly: System.ComponentModel.dll [External]
Thread started: <Thread Pool> #2
Thread started: <Thread Pool> #3
Thread started: <Thread Pool> #4
Thread started: <Thread Pool> #5
Loaded assembly: System.Linq.Queryable.dll [External]
Loaded assembly: Anonymously Hosted DynamicMethods Assembly [External]
Loaded assembly: System.Data.Common.dll [External]
Loaded assembly: System.Data.dll [External]
Thread started: <Thread Pool> #6
Loaded assembly: System.Diagnostics.Tracing.dll [External]
Loaded assembly: System.ComponentModel.Annotations.dll [External]
Loaded assembly: System.ComponentModel.DataAnnotations.dll [External]

编辑3： 根据评论收到的每个建议在不同的设备上测试。这些是结果（来自发布版本）

~8到10秒
~6-7秒
~Redmi Note 3上4-5秒
~9.5秒

编辑4： 我已经做了非常详细的测试，我可以确认“context.Migrate（）和使用SingleOrDefault（）的简单查询”（EFCore）需要9秒。如果我删除此呼叫，应用程序将在~3秒内启动。

编辑5： 我期望在splash活动中的不同线程上执行db init（如下所示），因为Xamarin.Forms初始化（通常）大约需要3秒，我希望init也可以并行执行。但是看起来即使它在不同的线程上运行，EFCore db init也会影响启动时间。我做错了吗？

 protected override void OnResume()
    {
        base.OnResume();

        System.Threading.Tasks.Task.Run(() =>
        {
            App.DbFolder = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
            App.InitializeDb();
        });

        StartActivity(typeof(MainActivity));

    }

有任何建议的帮助吗？

Answer 1

如果这是应用程序何时完成加载的准确表示，则本节将介绍4.5秒。

04-01 07:53:15.443 D/Mono    ( 1742): [0x9ac5e930] hill climbing, change max number of threads 2
04-01 07:53:15.445 W/art     ( 1742): JNI RegisterNativeMethods: attempt to register 0 native methods for md54ada4fbe4a5955f6151fa282d30cfc48.SelfDisposingBitmapDrawable
Resolved pending breakpoint at 'CleanUpReceiver.cs:16,1' to void extrony.Droid.Receivers.CleanUpReceiver.OnReceive (Android.Content.Context context, Android.Content.Intent intent) [0x00000].
04-01 07:53:20.059 D/Mono    ( 1742): DllImport searching in: '/system/lib/libsqlite.so' ('/system/lib/libsqlite.so').
04-01 07:53:20.059 D/Mono    ( 1742): Searching for 'sqlite3_column_count'.

此时所有内容都已加载，因此它是您代码中的内容，很可能是在App.xaml.cs构造函数中。我注意到你也有EF Core。

这里可能会发生很多事情，但是在App.xaml.cs完成之前，它仍会显示启动画面。

我建议在启动时在部分代码中添加一个StopWatch，看看花了多少时间。从那里你可以在stackoverflow中提出一个与该问题相关的不同问题。

System.Diagnostics.Stopwatch s = new System.Diagnostics.Stopwatch();
s.Start();

// Code in here

s.Stop();
System.Diagnostics.Debug.WriteLine($"Elapsed Time: {s.ElapsedMilliseconds.ToString("N0")}");

Answer 2

如果主页调用服务，加载数据或执行需要一些时间才能完成的操作，则可以添加启动画面。这解决了我在android上的问题。

http://www.c-sharpcorner.com/UploadFile/oussamaalrifai/xamarin-forms-android-workaround-for-splash-screen-with-lo/

Xamarin.Forms Android Startup需要10秒

2 个答案: