异步任务似乎是最近最严格的实施之一。我实际上不想在这里使用多线程但是异步任务。在我的下面的代码中，我已经实现了异步任务来从firebase获取我的数据到我的应用程序。即使我使用的是异步任务，这也是我在用户界面上遇到的问题。
我有3项活动。该应用程序启动到第一个活动，没有用户遇到任何形式的滞后。当我从第一个活动导航到第二个活动时，导航抽屉布局在第二个活动的数据出现之前滞后几秒钟，因此对于活动3，导致抽屉布局滞后。当我在3个活动之间导航时，它会平滑移动。 （意思是它在从一个活动移动到另一个活动之前就会滞后，然后才能顺利移动）。
请注意，当我在OnResume（）中注释this.refreshAll()时，它会顺利移动
我的异步是否已经很好地实现了？
活性2
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
fab = FindViewById<FloatingActionButton>(Resource.Id.fab);
fab.Click += delegate
{
LayoutInflater HeroInflater = LayoutInflater.From(this);
View mView = peaceHeroInflater.Inflate(Resource.Layout.HeroDialog, null);
Android.Support.V7.App.AlertDialog.Builder alertDialogBuilder = new Android.Support.V7.App.AlertDialog.Builder(this);
alertDialogBuilder.SetView(mView);
var HeroName = mView.FindViewById<EditText>(Resource.Id.editText1);
alertDialogBuilder.SetCancelable(false)
.SetPositiveButton("Save", async delegate
{
Hero hero = new Hero();
hero.Uid = string.Empty;
hero.Name = HeroName.Text;
var firebase = new FirebaseClient(FirebaseUrl);
var item = await firebase.Child("sometable").PostAsync<PeaceHero>(hero);
await ReloadData();
})
.SetNegativeButton("Cancel", delegate
{
alertDialogBuilder.Dispose();
});
Android.Support.V7.App.AlertDialog alertDialogAndroid = alertDialogBuilder.Create();
alertDialogAndroid.Show();
};
}
private async void refreshAll()
{
await ReloadData();
}
private async Task ReloadData()
{
var firebase = new FirebaseClient(FirebaseUrl);
var items = await firebase.Child("sometable").OnceAsync<>();
foreach (var item in items)
{
Hero details = new Hero();
details.Uid = item.Key;
details.Name = item.Object.Name;
add_Hero.Add(details);
}
rv.SetLayoutManager(new LinearLayoutManager(this));
rv.SetItemAnimator(new DefaultItemAnimator());
}
protected override void OnResume()
{
base.OnResume();
this.refreshAll();
}
更新
private async Task refreshAll()
{
await RefreshData();
}
protected async override void OnResume()
{
base.OnResume();
await refreshAll();
}
LOG
[Mono] AOT: image 'Mono.Security.dll.so' not found: dlopen failed: library "/data/app-lib/com.companyname.peaceapp.peaceapp-130/libaot-Mono.Security.dll.so" not found
[Mono] AOT: image '/usr/local/lib/mono/aot-cache/arm/Mono.Security.dll.so' not found: dlopen failed: library "/data/app-lib/com.companyname.peaceapp.peaceapp-130/libaot-Mono.Security.dll.so" not found
[Mono] Config attempting to parse: 'Mono.Security.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/Mono.Security/Mono.Security.config'.
[Mono] Assembly Ref addref System[0x86e311a8] -> Mono.Security[0x8792d7e8]: 2
[Mono] Assembly Ref addref Mono.Security[0x8792d7e8] -> mscorlib[0x73d41ac0]: 68
Loaded assembly: Mono.Security.dll [External]
[Mono] Assembly Ref addref System.Net.Http[0x8649e068] -> System.Core[0x7f2bf708]: 9
[Mono] Assembly Ref addref Mono.Android[0x7f1692f0] -> System[0x86e311a8]: 7
Thread started: <Thread Pool> #4
Thread started: <Thread Pool> #5
[Mono] [0x87aecc90] worker starting
Thread started: <Thread Pool> #6
[Mono] [0x87b045b0] worker starting
Thread started: <Thread Pool> #7
[Mono] [0x87ae1a88] worker starting
[Choreographer] Skipped 80 frames! The application may be doing too much work on its main thread.
[RecyclerView] No adapter attached; skipping layout
[ProgressBar] updateDrawableBounds: left = 72
[ProgressBar] updateDrawableBounds: top = 0
[ProgressBar] updateDrawableBounds: right = 72
[ProgressBar] updateDrawableBounds: bottom = 0
[Mono] [0x87aecc90] hill climbing, change max number of threads 4
[RecyclerView] No adapter attached; skipping layout
[Mono] Assembly Ref addref Mono.Security[0x8792d7e8] -> System[0x86e311a8]: 8
Thread started: <Thread Pool> #8
Thread started: <Thread Pool> #9
[Mono] [0x851329e8] worker starting
Thread started: <Thread Pool> #10
[Mono] [0x85132de0] worker starting
[Mono] Unloading image System.dll [0x851046d8].
[Mono] Image addref System[0x8548b280] -> System.dll[0x86e30720]: 5
[Mono] Config attempting to parse: 'System.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/System/System.config'.
[Mono] Unloading image System.dll [0x851046d8].
[Mono] Image addref System[0x8548f438] -> System.dll[0x86e30720]: 6
[Mono] Config attempting to parse: 'System.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/System/System.config'.
[Mono] Unloading image System.dll [0x851046d8].
[Mono] Image addref System[0x854829d8] -> System.dll[0x86e30720]: 7
[Mono] Config attempting to parse: 'System.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/System/System.config'.
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_is_assignable_from'.
[Mono] Probing 'java_interop_jnienv_is_assignable_from'.
[Mono] Found as 'java_interop_jnienv_is_assignable_from'.
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_get_byte_array_region'.
[Mono] Probing 'java_interop_jnienv_get_byte_array_region'.
[Mono] Found as 'java_interop_jnienv_get_byte_array_region'.
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_set_byte_array_region'.
[Mono] Probing 'java_interop_jnienv_set_byte_array_region'.
[Mono] Found as 'java_interop_jnienv_set_byte_array_region'.
[Mono] The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
[Mono] Unloading image System.Core.dll [0x854f61d0].
[Mono] Image addref System.Core[0x85501bf0] -> System.Core.dll[0x7f2bedb0]: 5
[Mono] Config attempting to parse: 'System.Core.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/System.Core/System.Core.config'.
[Mono] The request to load the assembly System.Core v4.0.0.0 was remapped to v2.0.5.0
[Mono] Unloading image System.Core.dll [0x855214c8].
[Mono] Image addref System.Core[0x84ff8888] -> System.Core.dll[0x7f2bedb0]: 6
[Mono] Config attempting to parse: 'System.Core.dll.config'.
[Mono] Config attempting to parse: '/usr/local/etc/mono/assemblies/System.Core/System.Core.config'.
[Mono] [0x851329e8] hill climbing, change max number of threads 5
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_get_static_field_id'.
[Mono] Probing 'java_interop_jnienv_get_static_field_id'.
[Mono] Found as 'java_interop_jnienv_get_static_field_id'.
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_get_static_object_field'.
[Mono] Probing 'java_interop_jnienv_get_static_object_field'.
[Mono] Found as 'java_interop_jnienv_get_static_object_field'.
[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_call_boolean_method_a'.
[Mono] Probing 'java_interop_jnienv_call_boolean_method_a'.
[Mono] Found as 'java_interop_jnienv_call_boolean_method_a'.
Thread finished: <Thread Pool> #10
[Mono] [0x85132de0] worker finishing
答案 0 :(得分：0)
left:50%,transform:translate(-50%), display:inline,block, margin: auto中的this.refreshAll()来电可能会被阻止。尝试制作OnResume() OnResume()并等待async的结果。
this.refreshAll()这至少应该允许UI在加载数据时保持响应。我的猜测是protected async override void OnResume()
{
base.OnResume();
await this.refreshAll();
}
可能会在调用之间缓存您的结果（可能只是寻找更改），因此在初始调用之后要做的工作要少得多。
请注意，在生命周期事件中放置async / await可能会产生意想不到的后果 - 例如，如果OnceAsync<>()方法等待的呼叫需要花费时间，async OnCreate()和{{1}方法通常在OnStart()完成之前启动。
答案 1 :(得分：0)
可重用的异步任务
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
namespace Android.Basic.Core
{
public class AsyncTasker : AsyncTask<Java.Lang.Void, Java.Lang.Void, Java.Lang.Void>
{
private Action Action { get; }
public event EventHandler<object> TaskCompleted;
public void NotifyCompletedTask(object result)
{
Xamarin.Essentials.MainThread.BeginInvokeOnMainThread(() =>
{
this.TaskCompleted?.Invoke(this, result);
});
}
public AsyncTasker(Action action)
{
this.Action = action;
}
protected override Java.Lang.Void RunInBackground(params Java.Lang.Void[] @params)
{
if (this.Action == null)
return null;
this.Action();
return null;
}
}
}
用法
var asyncTasker = new AsyncTasker(() =>
{
//Do non UI task, Use "MainThread.BeginInvokeOnMainThread" to update UI.
//Notify that task completed
asyncTasker.NotifyCompletedTask(null);
});
asyncTasker.TaskCompleted += delegate
{
Xamarin.Essentials.MainThread.BeginInvokeOnMainThread(() =>
{
//Do completed task
});
};
asyncTasker.Execute();