WPF/C#：程序关闭的三种模式

ShutdownMode枚举类型介绍

ShutdownMode是一个枚举类型，它定义了WPF应用程序的关闭方式。这个枚举类型有三个成员：

• OnLastWindowClose：当最后一个窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
• OnMainWindowClose：当主窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
• OnExplicitShutdown：只有当调用System.Windows.Application.Shutdown方法时，应用程序才会关闭。

整理成表格如下所示：

枚举成员	含义
OnLastWindowClose	当最后一个窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
OnMainWindowClose	当主窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
OnExplicitShutdown	只有当调用System.Windows.Application.Shutdown方法时，应用程序才会关闭。

实践

MainWindow的xaml如下：

<Window x:Class="ApplicationShutdown.MainWindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"         xmlns:local="clr-namespace:ApplicationShutdown"         mc:Ignorable="d"         Title="MainWindow" Height="350" Width="525" Loaded="MainWindow_Loaded">     <DockPanel>         <StackPanel DockPanel.Dock="Top" Orientation="Horizontal">             <Label HorizontalAlignment="Left">Shutdown Mode:</Label>             <ComboBox HorizontalAlignment="Left" Name="shutdownModeListBox" />         </StackPanel>         <StackPanel DockPanel.Dock="Top" Orientation="Horizontal">             <Label HorizontalAlignment="Left">Application Exit Code (for explicit shutdown):</Label>             <TextBox HorizontalAlignment="Left" Name="appExitCodeTextBox">0</TextBox>         </StackPanel>         <Button DockPanel.Dock="Top" Click="newWindowButton_Click">New Window</Button>         <Button DockPanel.Dock="Top" Click="explicitShutdownButton_Click">Shutdown Explicitly (Passing Exit Code)</Button>         <Canvas />     </DockPanel> </Window> 

MainWindow的cs如下：

using System; using System.Windows; using System.Windows.Controls;  namespace ApplicationShutdown {     /// <summary>     ///     Interaction logic for MainWindow.xaml     /// </summary>     public partial class MainWindow : Window     {         public MainWindow()         {             InitializeComponent();         }          private void MainWindow_Loaded(object sender, RoutedEventArgs e)         {             shutdownModeListBox.Items.Add("OnLastWindowClose");             shutdownModeListBox.Items.Add("OnExplicitShutdown");             shutdownModeListBox.Items.Add("OnMainWindowClose");             shutdownModeListBox.SelectedValue = "OnLastWindowClose";             shutdownModeListBox.SelectionChanged +=                 shutdownModeListBox_SelectionChanged;             Application.Current.ShutdownMode = ShutdownMode.OnLastWindowClose;         }          private void shutdownModeListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)         {             Application.Current.ShutdownMode =                 (ShutdownMode) Enum.Parse(typeof (ShutdownMode), shutdownModeListBox.SelectedValue.ToString());         }          private void newWindowButton_Click(object sender, RoutedEventArgs e)         {             (new ChildWindow()).Show();         }          private void explicitShutdownButton_Click(object sender, RoutedEventArgs e)         {             var exitCode = 0;             int.TryParse(appExitCodeTextBox.Text, out exitCode);             Application.Current.Shutdown(exitCode);         }     } } 

ChildWindow的xaml如下：

<Window x:Class="ApplicationShutdown.ChildWindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"         xmlns:local="clr-namespace:ApplicationShutdown"         mc:Ignorable="d"         Title="ChildWindow" Height="300"          Width="300"              Closing="ChildWindow_Closing"          Closed="ChildWindow_Closed">     <Grid/> </Window> 

ChildWindow的cs如下：

using System; using System.ComponentModel; using System.Windows;  namespace ApplicationShutdown {     /// <summary>     ///     Interaction logic for ChildWindow.xaml     /// </summary>     public partial class ChildWindow : Window     {         public ChildWindow()         {             InitializeComponent();         }          private void ChildWindow_Closing(object sender, CancelEventArgs e)         {             Console.WriteLine(@"Closing");             var result = MessageBox.Show("Allow Shutdown?", "Application Shutdown Sample",                 MessageBoxButton.YesNo,                 MessageBoxImage.Question);             e.Cancel = (result == MessageBoxResult.No);         }          private void ChildWindow_Closed(object sender, EventArgs e)         {             Console.WriteLine(@"Closed");         }     } } 

OnLastWindowClose

当最后一个窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。

最后一个窗口关闭:

调用System.Windows.Application.Shutdown方法:

OnMainWindowClose

当主窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。

主窗口关闭：

或者调用System.Windows.Application.Shutdown方法关闭，与上面效果相同，这里就不重复了。

OnExplicitShutdown

只有当调用System.Windows.Application.Shutdown方法时，应用程序才会关闭。

普通关闭：

关闭所有窗口之后，程序并不会停止。

调用System.Windows.Application.Shutdown方法:

总结

本文介绍了WPF程序的三种不同的关闭模式，分别是OnLastWindowClose、OnMainWindowClose与OnExplicitShutdown。

• OnLastWindowClose：当最后一个窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
• OnMainWindowClose：当主窗口关闭或者调用System.Windows.Application.Shutdown方法时，应用程序会关闭。
• OnExplicitShutdown：只有当调用System.Windows.Application.Shutdown方法时，应用程序才会关闭。

借助图解更好理解：

代码来源

[WPF-Samples/Application Management/ApplicationShutdown at main · microsoft/WPF-Samples (github.com)](https://github.com/microsoft/WPF-Samples/tree/main/Application Management/ApplicationShutdown)