如何从OnLaunched()重写Template10

Question

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我试图在模板10 Windows中重写OnLaunched()函数，但问题是它被密封在模板10 BootStrapper类中(它继承了应用程序类)。

以下是我的方法：

using Windows.UI.Xaml;
...

namespace Sample {
...
sealed partial class App : Template10.Common.BootStrapper {

protected override void OnLaunched(LaunchActivatedEventArgs args)
{

    /*************** My stuff *****************
    ***********************************************/
}
...
}

我正在为这个应用程序使用Template10空白应用程序，BootStrapper类中的OnLaunched()方法如下：

namespace Template10.Common
{
public abstract class BootStrapper : Application
{
    ...
    protected sealed override void OnLaunched(LaunchActivatedEventArgs e);
    ...
}
...
}

我无法从OnLaunched()中删除BootStrapper中的密封修饰符(猜测是因为它是“从元数据中删除的”)。

在抽象类中包含一个密封的方法有什么意义？

我们是否有其他方法来覆盖，如OnResume()、OnStartAsync()等，而不是OnLaunched()？

更新:供参考，以下是BootStrapper中的所有成员：

public abstract class BootStrapper : Application
{
    public const string DefaultTileID = "App";

    protected BootStrapper();

    public static BootStrapper Current { get; }
    public TimeSpan CacheMaxDuration { get; set; }
    public INavigationService NavigationService { get; }
    public StateItems SessionState { get; set; }
    public bool ShowShellBackButton { get; set; }
    protected Func<SplashScreen, UserControl> SplashFactory { get; set; }

    public event EventHandler<WindowCreatedEventArgs> WindowCreated;

    public static AdditionalKinds DetermineStartCause(IActivatedEventArgs args);
    public NavigationService NavigationServiceFactory(BackButton backButton, ExistingContent existingContent);
    [AsyncStateMachine(typeof(<OnInitializeAsync>d__44))]
    public virtual Task OnInitializeAsync(IActivatedEventArgs args);
    public virtual void OnResuming(object s, object e);
    public abstract Task OnStartAsync(StartKind startKind, IActivatedEventArgs args);
    [AsyncStateMachine(typeof(<OnSuspendingAsync>d__45))]
    public virtual Task OnSuspendingAsync(object s, SuspendingEventArgs e);
    public Dictionary<T, Type> PageKeys<T>() where T : struct, IConvertible;
    public virtual T Resolve<T>(Type type);
    public virtual INavigable ResolveForPage(Type page, NavigationService navigationService);
    public void UpdateShellBackButton();
    [AsyncStateMachine(typeof(<OnActivated>d__26))]
    protected sealed override void OnActivated(IActivatedEventArgs e);
    [AsyncStateMachine(typeof(<OnCachedFileUpdaterActivated>d__27))]
    protected sealed override void OnCachedFileUpdaterActivated(CachedFileUpdaterActivatedEventArgs args);
    [AsyncStateMachine(typeof(<OnFileActivated>d__28))]
    protected sealed override void OnFileActivated(FileActivatedEventArgs args);
    [AsyncStateMachine(typeof(<OnFileOpenPickerActivated>d__29))]
    protected sealed override void OnFileOpenPickerActivated(FileOpenPickerActivatedEventArgs args);
    [AsyncStateMachine(typeof(<OnFileSavePickerActivated>d__30))]
    protected sealed override void OnFileSavePickerActivated(FileSavePickerActivatedEventArgs args);
    protected sealed override void OnLaunched(LaunchActivatedEventArgs e);
    [AsyncStateMachine(typeof(<OnSearchActivated>d__31))]
    protected sealed override void OnSearchActivated(SearchActivatedEventArgs args);
    [AsyncStateMachine(typeof(<OnShareTargetActivated>d__32))]
    protected sealed override void OnShareTargetActivated(ShareTargetActivatedEventArgs args);
    protected sealed override void OnWindowCreated(WindowCreatedEventArgs args);

    public enum AdditionalKinds
    {
        Primary,
        Toast,
        SecondaryTile,
        Other
    }
    public enum BackButton
    {
        Attach,
        Ignore
    }
    public enum ExistingContent
    {
        Include,
        Exclude
    }
    public enum StartKind
    {
        Launch,
        Activate
    }
}

请帮助:}

Answer 1

模板10不允许我们覆盖OnLaunched()方法。相反，我们可以为此覆盖OnInitializeAsync()和OnStartAsync()方法。

原因是模板10建议我们使用称为单页模型的东西，它只不过是使用Page类的一个实例来放入框架提供的空框架中。这对我们有什么好处？如果我们需要在应用程序中放置菜单，比如说汉堡菜单，那么我们需要在应用程序中创建的每一页中复制菜单的代码。这会导致冗余、不一致、湿代码等问题。

因此，模板10最初创建一个名为Shell的Page，然后将每个页面的内容加载到此Shell页面中，而不是创建新页面。

我们可以通过以下方式覆盖这些方法：

sealed partial class App : BootStrapper
{
public App()
{
    this.InitializeComponent();
}

public override Task OnInitializeAsync(IActivatedEventArgs args)
{
    var nav = NavigationServiceFactory(BackButton.Attach, ExistingContent.Include);
    Window.Current.Content = new Views.Shell(nav);
    return Task.FromResult<object>(null);
}

public override Task OnStartAsync(BootStrapper.StartKind startKind, IActivatedEventArgs args)
{
    NavigationService.Navigate(typeof(Views.MainPage));
    return Task.FromResult<object>(null);
}
}

在这里我想出了答案：https://github.com/Windows-XAML/Template10/wiki/Docs-%7C-HamburgerMenu

因此，长话短说，重写OnInitializeAsync()或OnStartAsync()，而不是OnLaunched()。

Answer 2

您正试图在OnLaunched中重写MyPage.xaml.cs，而我可以非常安全地假设您的MyPage类不是从应用程序继承的。因此，它没有OnLaunched()方法(至少没有该签名)。您需要做的是在App.xaml.cs中重写它，因为它是Application.OnLaunched()。App.xaml.cs中的App类继承了应用程序。

顺便提一下，这是来自空白应用程序模板的示例，您已经提到了：

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