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)
