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)
