Avalonia框架MVVM模式打开和关闭当前界面_avalonia communitytoolkit

Avalonia框架MVVM模式打开和关闭当前界面和WPF的MVVM模式是一致的，区别只在于Avalonia是跨平台的。本文主要是记录Avalonia框架MVVM模式打开和关闭当前界面，主要是参考了十月的寒流的WPF中如何在MVVM模式下关闭窗口这个视频，有兴趣可以看看，里面提供多种方法实现打开和关闭当前界面。因为选择MVVM模式，下载CommunityToolkit.Mvvm库，具体步骤如下：

第一：实现简单的Avalonia界面，包括关闭和最小化两个按钮。

 项目的结构没有变化，主要需要关注的是Command和CommandParameter，这关系到按钮功能的实现。源码如下：

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="using:AvaloniaMVVMTest.ViewModels"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaMVVMTest.Views.MainWindow"
        x:DataType="vm:MainWindowViewModel"
        Icon="/Assets/avalonia-logo.ico"
        Title="AvaloniaMVVMTest">
	
    <Design.DataContext>
        <vm:MainWindowViewModel/>
    </Design.DataContext>
 
	<Grid>
		<StackPanel Margin="100,0,0,0"  Orientation="Horizontal">
			<TextBlock Text="{Binding Greeting}" Margin="100,0,0,0" HorizontalAlignment="Center" VerticalAlignment="Center"/>
		</StackPanel>
		<StackPanel Margin="100,100,0,0" Orientation="Horizontal">
			<Button Content="关闭" Command="{Binding CloseWindowCommand}" CommandParameter="{Binding}"
					Height="35" Width="50" Margin="100,0,0,0" HorizontalAlignment="Center" VerticalAlignment="Center"/>
			<Button Content="最小化" Command="{Binding MinimizedWindowCommand}" CommandParameter="{Binding}"
					Height="35" Width="70"  Margin="50,0,0,0" HorizontalAlignment="Center" VerticalAlignment="Center"/>
		</StackPanel>
	</Grid>
	
</Window>

其次是改造MainWindowViewModel。

第一步是通过选择管理NuGet包。搜索Microsoft.Toolkit.Mvvm并安装它，步骤见下图；

 第二步是绑定按钮的Command，因为运用了 CommunityToolkit.Mvvm库，所以代码看起来比调用ReactiveObject接口的简洁很多。通过 [ObservableObject]引入CommunityToolkit.Mvvm，通过[RelayCommand]简化Command方法的定义。

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using CommunityToolkit.Mvvm.Messaging;
using System;
 
namespace AvaloniaMVVMTest.ViewModels
{
    [ObservableObject]
    public partial class MainWindowViewModel 
    {
        public string Greeting => "Welcome to Avalonia!";
 
        //最小化窗口
        [RelayCommand]
        void MinimizedWindow()
        {
           
        }
 
        //关闭窗口
        [RelayCommand]
        void CloseWindow()
        {
            
        }
    }
}

第三步通过WeakReferenceMessenger实现功能，WeakReferenceMessenger是CommunityToolkit.Mvvm的信使弱引用。创建Messenger文件夹，在创建CloseWindowMessage和MinimizedWindowMessage类。

CloseWindowMessage类如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace AvaloniaMVVMTest.Messenger
{
     class CloseWindowMessage
    {
        public WeakReference? Sender { get; set; }
    }
}

MinimizedWindowMessage类如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace AvaloniaMVVMTest.Messenger
{
    class MinimizedWindowMessage
    {
        public WeakReference? Sender { get; set; }
    }
}

第四步在MainWindowViewModel中补充[RelayCommand]下的方法内容，重点关注标红的内容。

 //最小化窗口
        [RelayCommand]
        void MinimizedWindow()
        {
            WeakReferenceMessenger.Default.Send(new MinimizedWindowMessage
            {
                Sender = new WeakReference(this)
            });
 
        }
 
        //关闭窗口
        [RelayCommand]
        void CloseWindow()
        {
            WeakReferenceMessenger.Default.Send(new CloseWindowMessage
            {
                Sender = new WeakReference(this)
            });
        }

再次需要改造MainWindow.axaml.cs的数据绑定，见下图

using Avalonia.Controls;
using AvaloniaMVVMTest.Messenger;
using AvaloniaMVVMTest.ViewModels;
using CommunityToolkit.Mvvm.Messaging;
 
namespace AvaloniaMVVMTest.Views
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new MainWindowViewModel();
            //关闭窗口
            WeakReferenceMessenger.Default.Register<CloseWindowMessage>(this, (_, m) =>
            {
                this.Close();
            });
            //最小化窗口
            WeakReferenceMessenger.Default.Register<MinimizedWindowMessage>(this, (_, m) =>
            {
                this.WindowState = WindowState.Minimized;
            });
        }
    }
}

 最后就实现了Avalonia框架MVVM模式打开和关闭当前界面，希望本文对你可以有帮助。