wpf 通过IOC思想在MVVM的ViewModel里面打开其他窗口的方法

理论：在MVVM中，View通过添加ViewModel的引用来指定DataContext,也就是View可以引用ViewModel，但ViewModel不可以引用View，而ViewModel在实现逻辑过程中如果需要访问其他的窗体该怎么办呢，比如打开一个对话框，这里通过IOC思想来解决该问题。

1 新建wpf应用

2 新建Views，Models，ViewModels文件夹

3 新建Base文件夹，在其里面添加CommandBase类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace WpfApp1.Base
{
    public class CommandBase : ICommand
    {
        public event EventHandler CanExecuteChanged;

        public bool CanExecute(object parameter)
        {
            return true;
        }

        public void Execute(object parameter)
        {
            DoExecute?.Invoke();
        }

        public Action DoExecute { get; set; }


        public CommandBase(Action doExecute)
        {
            this.DoExecute = doExecute;
        }
    }
}

4 在Base里面新建WindowManager类，该类就是用IOC思想创建的第三方类，通过其来解耦ViewModel和View，该类通过一个注册方法来注册，并通过显示方法来获取并显示

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace WpfApp1.Base
{
    public class WindowManager
    {
        private static Dictionary<string, Type> _Windows = new Dictionary<string, Type>();

        public static void Register(Type type,string key)
        {
            if (!_Windows.ContainsKey(key))
            {
                _Windows.Add(key, type);
            }
        }

        public static bool ShowWindow(string key)
        {
            if (_Windows.ContainsKey(key))
            {
                Type type = _Windows[key];
                Window win = (Window)Activator.CreateInstance(type);
                return win.ShowDialog() == true;
            }
            return false;
        }
    }
}

5 在Views里面添加一个窗体Window1，实现对话框功能

<Window x:Class="WpfApp1.Views.Window1"
        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:WpfApp1.Views"
        mc:Ignorable="d"
        Title="Window1" Height="450" Width="800">
    <Grid>
        <Button Content="ok" Click="Button_Click" />
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace WpfApp1.Views
{
    /// <summary>
    /// Window1.xaml 的交互逻辑
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            this.DialogResult = true;
        }
    }
}

6 在ViewModels里面新建MainViewModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using WpfApp1.Base;
using WpfApp1.Models;

namespace WpfApp1.ViewModels
{
    public class MainViewModel
    {

        public ICommand btnCommand { get; set; }


        public MainViewModel()
        {
            btnCommand = new CommandBase(() =>
            {
                WindowManager.ShowWindow("window1");
            });
        }
    }
}

7 修改MainWindow

<Window x:Class="WpfApp1.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:WpfApp1"
        xmlns:vm="clr-namespace:WpfApp1.ViewModels"
        mc:Ignorable="d" FontSize="30"
        Title="MainWindow" Height="450" Width="800">
    <Window.DataContext>
        <vm:MainViewModel />
    </Window.DataContext>
    <Grid>
        <Button Content="test" Command="{Binding btnCommand}" />
    </Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using WpfApp1.Base;
using WpfApp1.Views;

namespace WpfApp1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            WindowManager.Register(typeof(Window1), "window1");
        }
    }
}

注意：在MainWindow的构造函数中将Window1注册到WindowManager中，然后就可以在MainViewModel中通过WindowManger拿到并显示出来