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)
