2.WPF程序Application的生命周期02-21

WPF程序的生命周期由 Application 类控制。Application 类是WPF程序中的核心类，它负责管理整个应用程序的启动、运行和关闭。理解WPF应用程序的生命周期对于开发高效且可维护的WPF应用非常重要。以下是详细讲解WPF程序中 Application 的生命周期。

1. 启动阶段

WPF应用程序的启动由 App.xaml 文件中的 Application 类控制。App.xaml 文件中定义了应用程序的资源、事件处理程序等。应用程序的启动过程通常分为以下几个阶段：

(1) `App.xaml` 被加载

在WPF应用程序启动时，App.xaml 文件会被加载。这个文件包含了应用程序的基础配置和资源。在 App.xaml 中，可以定义全局的资源字典、样式、主题等资源。

<Application x:Class="WpfApp1.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
</Application>

x:Class 属性指定了 Application 类的完全限定名。
StartupUri 属性指定了应用程序启动时加载的窗口（例如，MainWindow.xaml）。

(2) `App` 类的初始化

App.xaml 会通过自动生成的 App.xaml.cs 类进行初始化。App 类会创建并启动一个 Application 实例。你可以在 App.xaml.cs 中的构造函数或 OnStartup 方法中执行一些初始化逻辑。

public partial class App : Application
{
    public App()
    {
        // 这里可以执行一些初始化操作
    }
}

2. 启动阶段（`Startup` 事件）

在 App.xaml 中指定了 StartupUri 后，应用程序启动时，会触发 Startup 事件。Startup 事件是程序启动的一个重要时刻，通常可以在这个阶段执行一些应用程序级别的初始化代码。

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);
        
        // 你可以在这里添加应用程序的初始化代码
        // 比如，设置主窗口，启动必要的服务等
        MainWindow mainWindow = new MainWindow();
        mainWindow.Show();
    }
}

StartupEventArgs 中包含了启动参数（如果有的话）。
在 OnStartup 方法中，我们可以做很多事情，比如配置服务、设置主窗口、加载配置文件等。最重要的是，我们在这里通常会创建并显示主窗口。

3. 主窗口的显示

在 OnStartup 方法中，我们可以显式地创建主窗口并显示它。通常，MainWindow.xaml 文件会自动被指定为应用程序的主窗口，但你也可以在代码中手动创建并显示它。

MainWindow mainWindow = new MainWindow();
mainWindow.Show();

Show() 方法用于显示窗口。窗口显示后，用户可以与应用程序进行交互。

4. 运行阶段（`Run` 方法）

在 OnStartup 方法中，Application 对象的 Run 方法会被调用，这意味着应用程序进入了运行状态，开始处理消息循环。此时，应用程序将进入一个消息循环，等待用户输入和事件。

this.Run();  // 运行消息循环

Run() 方法的调用意味着应用程序开始接收和处理事件，直到应用程序退出。
Application.Run() 是WPF程序的核心方法，它启动了事件处理循环，并且直到应用程序退出前，事件循环会一直运行。

5. 关闭阶段（`Exit` 事件）

应用程序结束时，WPF会触发 Exit 事件。此时，应用程序已经完全关闭，所有窗口和资源已经释放。你可以在 Exit 事件中执行一些资源清理的操作。

public partial class App : Application
{
    protected override void OnExit(ExitEventArgs e)
    {
        base.OnExit(e);
        
        // 执行关闭前的清理操作，比如保存应用状态，释放资源等
    }
}

ExitEventArgs 中包含了退出时的退出代码，通常是退出的原因或者状态代码。

6. 生命周期的各个重要事件

WPF的 Application 类提供了多个事件，允许开发者在应用程序的不同生命周期阶段插入自定义逻辑：

Startup 事件：在应用程序启动时触发。在这里可以处理启动时的逻辑。
Activated 事件：在应用程序窗口被激活时触发。每次窗口被激活时都会触发。
Deactivated 事件：当应用程序窗口失去焦点时触发。通常用于暂停某些操作或更新状态。
Exit 事件：在应用程序退出时触发。用于资源清理等操作。

7. 退出阶段

退出阶段是应用程序生命周期的最后一个阶段。在这个阶段，WPF会销毁所有窗口并清理资源。一旦所有窗口关闭，Application.Run() 会返回，应用程序正式退出。

Application.Current.Shutdown();

调用 Shutdown() 方法会触发 Exit 事件并关闭应用程序。

8. Application的生命周期总结

加载App.xaml：系统加载应用程序配置和资源。
调用OnStartup：应用程序开始启动，执行初始化代码，创建并显示主窗口。
调用Run：应用程序进入消息循环，等待事件并响应用户交互。
调用OnExit：在应用程序退出时，执行清理操作。

小结

WPF应用程序的生命周期由 Application 类控制，涉及到多个重要的阶段：启动阶段、运行阶段、关闭阶段。Application 类为我们提供了丰富的事件和方法，可以用来管理和控制应用程序的各个生命周期阶段。理解这一生命周期对于有效管理WPF应用程序的状态、资源和用户交互非常关键。

源码

#region 程序集 PresentationFramework, Version=8.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
// C:\Program Files\dotnet\packs\Microsoft.WindowsDesktop.App.Ref\8.0.11\ref\net8.0\PresentationFramework.dll
#endregion

using System.Collections;
using System.Reflection;
using System.Windows.Markup;
using System.Windows.Navigation;
using System.Windows.Resources;
using System.Windows.Threading;

namespace System.Windows
{
    //
    // 摘要:
    //     Encapsulates a Windows Presentation Foundation application.
    public class Application : DispatcherObject, IQueryAmbient
    {
        //
        // 摘要:
        //     Initializes a new instance of the System.Windows.Application class.
        //
        // 异常:
        //   T:System.InvalidOperationException:
        //     More than one instance of the System.Windows.Application class is created per
        //     System.AppDomain.
        public Application();

        //
        // 摘要:
        //     Gets or sets the System.Reflection.Assembly that provides the pack uniform resource
        //     identifiers (URIs) for resources in a WPF application.
        //
        // 返回结果:
        //     A reference to the System.Reflection.Assembly that provides the pack uniform
        //     resource identifiers (URIs) for resources in a WPF application.
        //
        // 异常:
        //   T:System.InvalidOperationException:
        //     A WPF application has an entry assembly, or System.Windows.Application.ResourceAssembly
        //     has already been set.
        public static Assembly ResourceAssembly { get; set; }
        //
        // 摘要:
        //     Gets the System.Windows.Application object for the current System.AppDomain.
        //
        //
        // 返回结果:
        //     The System.Windows.Application object for the current System.AppDomain.
        public static Application Current { get; }
        //
        // 摘要:
        //     Gets or sets the main window of the application.
        //
        // 返回结果:
        //     A System.Windows.Window that is designated as the main application window.
        //
        // 异常:
        //   T:System.InvalidOperationException:
        //     System.Windows.Application.MainWindow is set from an application that's hosted
        //     in a browser, such as an XAML browser applications (XBAPs).
        public Window MainWindow { get; set; }
        //
        // 摘要:
        //     Gets a collection of application-scope properties.
        //
        // 返回结果:
        //     An System.Collections.IDictionary that contains the application-scope properties.
        public IDictionary Properties { get; }
        //
        // 摘要:
        //     Gets or sets a collection of application-scope resources, such as styles and
        //     brushes.
        //
        // 返回结果:
        //     A System.Windows.ResourceDictionary object that contains zero or more application-scope
        //     resources.
        [Ambient]
        public ResourceDictionary Resources { get; set; }
        //
        // 摘要:
        //     Gets or sets the condition that causes the System.Windows.Application.Shutdown
        //     method to be called.
        //
        // 返回结果:
        //     A System.Windows.ShutdownMode enumeration value. The default value is System.Windows.ShutdownMode.OnLastWindowClose.
        public ShutdownMode ShutdownMode { get; set; }
        //
        // 摘要:
        //     Gets or sets a UI that is automatically shown when an application starts.
        //
        // 返回结果:
        //     A System.Uri that refers to the UI that automatically opens when an application
        //     starts.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     System.Windows.Application.StartupUri is set with a value of null.
        public Uri StartupUri { get; set; }
        //
        // 摘要:
        //     Gets the instantiated windows in an application.
        //
        // 返回结果:
        //     A System.Windows.WindowCollection that contains references to all window objects
        //     in the current System.AppDomain.
        public WindowCollection Windows { get; }

        //
        // 摘要:
        //     Occurs when an application becomes the foreground application.
        public event EventHandler Activated;
        //
        // 摘要:
        //     Occurs when an application stops being the foreground application.
        public event EventHandler Deactivated;
        //
        // 摘要:
        //     Occurs just before an application shuts down and cannot be canceled.
        public event ExitEventHandler Exit;
        //
        // 摘要:
        //     Occurs when a navigator in the application begins navigation to a content fragment,
        //     Navigation occurs immediately if the desired fragment is in the current content,
        //     or after the source XAML content has been loaded if the desired fragment is in
        //     different content.
        public event FragmentNavigationEventHandler FragmentNavigation;
        //
        // 摘要:
        //     Occurs when content that was navigated to by a navigator in the application has
        //     been loaded, parsed, and has begun rendering.
        public event LoadCompletedEventHandler LoadCompleted;
        //
        // 摘要:
        //     Occurs when the content that is being navigated to by a navigator in the application
        //     has been found, although it may not have completed loading.
        public event NavigatedEventHandler Navigated;
        //
        // 摘要:
        //     Occurs when a new navigation is requested by a navigator in the application.
        public event NavigatingCancelEventHandler Navigating;
        //
        // 摘要:
        //     Occurs when an error occurs while a navigator in the application is navigating
        //     to the requested content.
        public event NavigationFailedEventHandler NavigationFailed;
        //
        // 摘要:
        //     Occurs periodically during a download that is being managed by a navigator in
        //     the application to provide navigation progress information.
        public event NavigationProgressEventHandler NavigationProgress;
        //
        // 摘要:
        //     Occurs when the StopLoading method of a navigator in the application is called,
        //     or when a new navigation is requested by a navigator while a current navigation
        //     is in progress.
        public event NavigationStoppedEventHandler NavigationStopped;
        //
        // 摘要:
        //     Occurs when an exception is thrown by an application but not handled.
        public event DispatcherUnhandledExceptionEventHandler DispatcherUnhandledException;
        //
        // 摘要:
        //     Occurs when the user ends the Windows session by logging off or shutting down
        //     the operating system.
        public event SessionEndingCancelEventHandler SessionEnding;
        //
        // 摘要:
        //     Occurs when the System.Windows.Application.Run method of the System.Windows.Application
        //     object is called.
        public event StartupEventHandler Startup;

        //
        // 摘要:
        //     Returns a resource stream for a content data file that is located at the specified
        //     System.Uri (see WPF Application Resource, Content, and Data Files).
        //
        // 参数:
        //   uriContent:
        //     The relative System.Uri that maps to a loose resource.
        //
        // 返回结果:
        //     A System.Windows.Resources.StreamResourceInfo that contains a content data file
        //     that is located at the specified System.Uri. If a loose resource is not found,
        //     null is returned.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     The System.Uri that is passed to System.Windows.Application.GetContentStream(System.Uri)
        //     is null.
        //
        //   T:System.ArgumentException:
        //     The System.Uri that is passed to System.Windows.Application.GetContentStream(System.Uri)
        //     is an absolute System.Uri.
        public static StreamResourceInfo GetContentStream(Uri uriContent);
        //
        // 摘要:
        //     Retrieves a cookie for the location specified by a System.Uri.
        //
        // 参数:
        //   uri:
        //     The System.Uri that specifies the location for which a cookie was created.
        //
        // 返回结果:
        //     A System.String value, if the cookie exists; otherwise, a System.ComponentModel.Win32Exception
        //     is thrown.
        //
        // 异常:
        //   T:System.ComponentModel.Win32Exception:
        //     A Win32 error is raised by the InternetGetCookie function (called by System.Windows.Application.GetCookie(System.Uri))
        //     if a problem occurs when attempting to retrieve the specified cookie.
        public static string GetCookie(Uri uri);
        //
        // 摘要:
        //     Returns a resource stream for a site-of-origin data file that is located at the
        //     specified System.Uri (see WPF Application Resource, Content, and Data Files).
        //
        //
        // 参数:
        //   uriRemote:
        //     The System.Uri that maps to a loose resource at the site of origin.
        //
        // 返回结果:
        //     A System.Windows.Resources.StreamResourceInfo that contains a resource stream
        //     for a site-of-origin data file that is located at the specified System.Uri. If
        //     the loose resource is not found, null is returned.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     The System.Uri that is passed to System.Windows.Application.GetRemoteStream(System.Uri)
        //     is null.
        //
        //   T:System.ArgumentException:
        //     The System.Uri that is passed to System.Windows.Application.GetRemoteStream(System.Uri)
        //     is either not relative, or is absolute but not in the pack://siteoforigin:,,,/
        //     form.
        public static StreamResourceInfo GetRemoteStream(Uri uriRemote);
        //
        // 摘要:
        //     Returns a resource stream for a resource data file that is located at the specified
        //     System.Uri (see WPF Application Resource, Content, and Data Files).
        //
        // 参数:
        //   uriResource:
        //     The System.Uri that maps to an embedded resource.
        //
        // 返回结果:
        //     A System.Windows.Resources.StreamResourceInfo that contains a resource stream
        //     for resource data file that is located at the specified System.Uri.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     The System.Uri that is passed to System.Windows.Application.GetResourceStream(System.Uri)
        //     is null.
        //
        //   T:System.ArgumentException:
        //     The System.Uri that is passed to System.Windows.Application.GetResourceStream(System.Uri)
        //     is either not relative, or is absolute but not in the pack://application:,,,/
        //     form.
        //
        //   T:System.IO.IOException:
        //     The System.Uri that is passed to System.Windows.Application.GetResourceStream(System.Uri)
        //     cannot be found.
        public static StreamResourceInfo GetResourceStream(Uri uriResource);
        //
        // 摘要:
        //     Loads a XAML file that is located at the specified uniform resource identifier
        //     (URI) and converts it to an instance of the object that is specified by the root
        //     element of the XAML file.
        //
        // 参数:
        //   component:
        //     An object of the same type as the root element of the XAML file.
        //
        //   resourceLocator:
        //     A System.Uri that maps to a relative XAML file.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     resourceLocator is null.
        //
        //   T:System.ArgumentException:
        //     The resourceLocator is an absolute URI.
        //
        //   T:System.Exception:
        //     component is of a type that does not match the root element of the XAML file.
        public static void LoadComponent(object component, Uri resourceLocator);
        //
        // 摘要:
        //     Loads a XAML file that is located at the specified uniform resource identifier
        //     (URI), and converts it to an instance of the object that is specified by the
        //     root element of the XAML file.
        //
        // 参数:
        //   resourceLocator:
        //     A System.Uri that maps to a relative XAML file.
        //
        // 返回结果:
        //     An instance of the root element specified by the XAML file loaded.
        //
        // 异常:
        //   T:System.ArgumentNullException:
        //     resourceLocator is null.
        //
        //   T:System.ArgumentException:
        //     The resourceLocator is an absolute URI.
        //
        //   T:System.Exception:
        //     The file is not a XAML file.
        public static object LoadComponent(Uri resourceLocator);
        //
        // 摘要:
        //     Creates a cookie for the location specified by a System.Uri.
        //
        // 参数:
        //   uri:
        //     The System.Uri that specifies the location for which the cookie should be created.
        //
        //
        //   value:
        //     The System.String that contains the cookie data.
        //
        // 异常:
        //   T:System.ComponentModel.Win32Exception:
        //     A Win32 error is raised by the InternetSetCookie function (called by System.Windows.Application.SetCookie(System.Uri,System.String))
        //     if a problem occurs when attempting to create the specified cookie.
        public static void SetCookie(Uri uri, string value);
        //
        // 摘要:
        //     Searches for a user interface (UI) resource, such as a System.Windows.Style or
        //     System.Windows.Media.Brush, with the specified key, and throws an exception if
        //     the requested resource is not found (see XAML Resources).
        //
        // 参数:
        //   resourceKey:
        //     The name of the resource to find.
        //
        // 返回结果:
        //     The requested resource object. If the requested resource is not found, a System.Windows.ResourceReferenceKeyNotFoundException
        //     is thrown.
        //
        // 异常:
        //   T:System.Windows.ResourceReferenceKeyNotFoundException:
        //     The resource cannot be found.
        public object FindResource(object resourceKey);
        //
        // 摘要:
        //     Starts a Windows Presentation Foundation application.
        //
        // 返回结果:
        //     The System.Int32 application exit code that is returned to the operating system
        //     when the application shuts down. By default, the exit code value is 0.
        //
        // 异常:
        //   T:System.InvalidOperationException:
        //     System.Windows.Application.Run is called from a browser-hosted application (for
        //     example, an XAML browser application (XBAP)).
        public int Run();
        //
        // 摘要:
        //     Starts a Windows Presentation Foundation application and opens the specified
        //     window.
        //
        // 参数:
        //   window:
        //     A System.Windows.Window that opens automatically when an application starts.
        //
        //
        // 返回结果:
        //     The System.Int32 application exit code that is returned to the operating system
        //     when the application shuts down. By default, the exit code value is 0.
        //
        // 异常:
        //   T:System.InvalidOperationException:
        //     System.Windows.Application.Run is called from a browser-hosted application (for
        //     example, an XAML browser application (XBAP)).
        public int Run(Window window);
        //
        // 摘要:
        //     Shuts down an application.
        public void Shutdown();
        //
        // 摘要:
        //     Shuts down an application that returns the specified exit code to the operating
        //     system.
        //
        // 参数:
        //   exitCode:
        //     An integer exit code for an application. The default exit code is 0.
        public void Shutdown(int exitCode);
        //
        // 摘要:
        //     Searches for the specified resource.
        //
        // 参数:
        //   resourceKey:
        //     The name of the resource to find.
        //
        // 返回结果:
        //     The requested resource object. If the requested resource is not found, a null
        //     reference is returned.
        public object TryFindResource(object resourceKey);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Activated event.
        //
        // 参数:
        //   e:
        //     An System.EventArgs that contains the event data.
        protected virtual void OnActivated(EventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Deactivated event.
        //
        // 参数:
        //   e:
        //     An System.EventArgs that contains the event data.
        protected virtual void OnDeactivated(EventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Exit event.
        //
        // 参数:
        //   e:
        //     An System.Windows.ExitEventArgs that contains the event data.
        protected virtual void OnExit(ExitEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.FragmentNavigation event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.FragmentNavigationEventArgs that contains the event
        //     data.
        protected virtual void OnFragmentNavigation(FragmentNavigationEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.LoadCompleted event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigationEventArgs that contains the event data.
        protected virtual void OnLoadCompleted(NavigationEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Navigated event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigationEventArgs that contains the event data.
        protected virtual void OnNavigated(NavigationEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Navigating event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigatingCancelEventArgs that contains the event
        //     data.
        protected virtual void OnNavigating(NavigatingCancelEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.NavigationFailed event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigationFailedEventArgs that contains the event
        //     data.
        protected virtual void OnNavigationFailed(NavigationFailedEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.NavigationProgress event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigationProgressEventArgs that contains the event
        //     data.
        protected virtual void OnNavigationProgress(NavigationProgressEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.NavigationStopped event.
        //
        // 参数:
        //   e:
        //     A System.Windows.Navigation.NavigationEventArgs that contains the event data.
        protected virtual void OnNavigationStopped(NavigationEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.SessionEnding event.
        //
        // 参数:
        //   e:
        //     A System.Windows.SessionEndingCancelEventArgs that contains the event data.
        protected virtual void OnSessionEnding(SessionEndingCancelEventArgs e);
        //
        // 摘要:
        //     Raises the System.Windows.Application.Startup event.
        //
        // 参数:
        //   e:
        //     A System.Windows.StartupEventArgs that contains the event data.
        protected virtual void OnStartup(StartupEventArgs e);
    }
}

posted @ 2025-02-21 23:55 阿遇而已阅读(12) 评论(0) 编辑收藏举报

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· WPF的APP生命周期以及全局异常捕获

· 1.Application和Window窗体的生命周期

· wpf-Application+Window窗体的生命周期

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ziyuhaokun

WPF程序Application的生命周期

1. 启动阶段

(1) `App.xaml` 被加载

(2) `App` 类的初始化

2. 启动阶段（`Startup` 事件）

3. 主窗口的显示

4. 运行阶段（`Run` 方法）

5. 关闭阶段（`Exit` 事件）

6. 生命周期的各个重要事件

7. 退出阶段

8. Application的生命周期总结

小结

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ziyuhaokun

WPF程序Application的生命周期

1. 启动阶段

(1) App.xaml 被加载

(2) App 类的初始化

2. 启动阶段（Startup 事件）

3. 主窗口的显示

4. 运行阶段（Run 方法）

5. 关闭阶段（Exit 事件）

6. 生命周期的各个重要事件

7. 退出阶段

8. Application的生命周期总结

小结

源码

公告

搜索

常用链接

合集

随笔档案

阅读排行榜

评论排行榜

推荐排行榜

最新评论

(1) `App.xaml` 被加载

(2) `App` 类的初始化

2. 启动阶段（`Startup` 事件）

4. 运行阶段（`Run` 方法）

5. 关闭阶段（`Exit` 事件）