我也遇到过同样的问题。我已经提出了一种在视图和视图模型之间进行交互的方法。您可以发起从ViewModel向View发送消息，告诉它显示一个消息框，然后它将报告返回结果。然后ViewModel可以响应从View返回的结果。

我在博客中对此进行了说明:

我知道这是一个老问题，但当我做这个搜索时，我发现了很多相关的问题，但我没有找到一个真正明确的回答。所以我做了我自己的对话框/消息框/popin的实现，我分享它! 我认为这是“MVVM证明”，我试着让它简单和适当，但我是WPF的新手，所以请随意评论，甚至提出拉请求。

https://github.com/Plasma-Paris/Plasma.WpfUtils

你可以这样使用它:

public RelayCommand YesNoMessageBoxCommand { get; private set; }
async void YesNoMessageBox()
{
    var result = await _Service.ShowMessage("This is the content of the message box", "This is the title", System.Windows.MessageBoxButton.YesNo);
    if (result == System.Windows.MessageBoxResult.Yes)
        // [...]
}

或者像这样，如果你想要更复杂的popin:

var result = await _Service.ShowCustomMessageBox(new MyMessageBoxViewModel { /* What you want */ });

它展示了这样的东西:

我已经实现了一个从ViewModel监听消息的行为。它基于Laurent Bugnion的解决方案，但由于它不使用代码，而且更可重用，所以我认为它更优雅。

如何使WPF的行为，如果MVVM是支持开箱即用

为什么不只是在VM中引发一个事件，然后在视图中订阅该事件呢?这将保持应用程序逻辑和视图分离，并且仍然允许您为对话框使用子窗口。

标准方法

在花了几年时间在WPF中处理这个问题之后，我终于找到了在WPF中实现对话框的标准方法。以下是这种方法的优点:

清洁 不违反MVVM设计模式 ViewModal从不引用任何UI库(WindowBase, PresentationFramework等) 非常适合自动化测试 对话框可以很容易地被替换。

那么关键是什么呢?是DI + IoC。

下面是它的工作原理。我正在使用MVVM Light，但这种方法也可以扩展到其他框架:

Add a WPF Application project to your solution. Call it App. Add a ViewModal Class Library. Call it VM. App references VM project. VM project doesn't know anything about App. Add NuGet reference to MVVM Light to both projects. I'm using MVVM Light Standard these days, but you are okay with the full Framework version too. Add an interface IDialogService to VM project: public interface IDialogService { void ShowMessage(string msg, bool isError); bool AskBooleanQuestion(string msg); string AskStringQuestion(string msg, string default_value); string ShowOpen(string filter, string initDir = "", string title = ""); string ShowSave(string filter, string initDir = "", string title = "", string fileName = ""); string ShowFolder(string initDir = ""); bool ShowSettings(); } Expose a public static property of IDialogService type in your ViewModelLocator, but leave registration part for the View layer to perform. This is the key.: public static IDialogService DialogService => SimpleIoc.Default.GetInstance<IDialogService>(); Add an implementation of this interface in the App project. public class DialogPresenter : IDialogService { private static OpenFileDialog dlgOpen = new OpenFileDialog(); private static SaveFileDialog dlgSave = new SaveFileDialog(); private static FolderBrowserDialog dlgFolder = new FolderBrowserDialog(); /// <summary> /// Displays a simple Information or Error message to the user. /// </summary> /// <param name="msg">String text that is to be displayed in the MessageBox</param> /// <param name="isError">If true, Error icon is displayed. If false, Information icon is displayed.</param> public void ShowMessage(string msg, bool isError) { if(isError) System.Windows.MessageBox.Show(msg, "Your Project Title", MessageBoxButton.OK, MessageBoxImage.Error); else System.Windows.MessageBox.Show(msg, "Your Project Title", MessageBoxButton.OK, MessageBoxImage.Information); } /// <summary> /// Displays a Yes/No MessageBox.Returns true if user clicks Yes, otherwise false. /// </summary> /// <param name="msg"></param> /// <returns></returns> public bool AskBooleanQuestion(string msg) { var Result = System.Windows.MessageBox.Show(msg, "Your Project Title", MessageBoxButton.YesNo, MessageBoxImage.Question) == MessageBoxResult.Yes; return Result; } /// <summary> /// Displays Save dialog. User can specify file filter, initial directory and dialog title. Returns full path of the selected file if /// user clicks Save button. Returns null if user clicks Cancel button. /// </summary> /// <param name="filter"></param> /// <param name="initDir"></param> /// <param name="title"></param> /// <param name="fileName"></param> /// <returns></returns> public string ShowSave(string filter, string initDir = "", string title = "", string fileName = "") { if (!string.IsNullOrEmpty(title)) dlgSave.Title = title; else dlgSave.Title = "Save"; if (!string.IsNullOrEmpty(fileName)) dlgSave.FileName = fileName; else dlgSave.FileName = ""; dlgSave.Filter = filter; if (!string.IsNullOrEmpty(initDir)) dlgSave.InitialDirectory = initDir; if (dlgSave.ShowDialog() == DialogResult.OK) return dlgSave.FileName; else return null; } public string ShowFolder(string initDir = "") { if (!string.IsNullOrEmpty(initDir)) dlgFolder.SelectedPath = initDir; if (dlgFolder.ShowDialog() == DialogResult.OK) return dlgFolder.SelectedPath; else return null; } /// <summary> /// Displays Open dialog. User can specify file filter, initial directory and dialog title. Returns full path of the selected file if /// user clicks Open button. Returns null if user clicks Cancel button. /// </summary> /// <param name="filter"></param> /// <param name="initDir"></param> /// <param name="title"></param> /// <returns></returns> public string ShowOpen(string filter, string initDir = "", string title = "") { if (!string.IsNullOrEmpty(title)) dlgOpen.Title = title; else dlgOpen.Title = "Open"; dlgOpen.Multiselect = false; dlgOpen.Filter = filter; if (!string.IsNullOrEmpty(initDir)) dlgOpen.InitialDirectory = initDir; if (dlgOpen.ShowDialog() == DialogResult.OK) return dlgOpen.FileName; else return null; } /// <summary> /// Shows Settings dialog. /// </summary> /// <returns>true if User clicks OK button, otherwise false.</returns> public bool ShowSettings() { var w = new SettingsWindow(); MakeChild(w); //Show this dialog as child of Microsoft Word window. var Result = w.ShowDialog().Value; return Result; } /// <summary> /// Prompts user for a single value input. First parameter specifies the message to be displayed in the dialog /// and the second string specifies the default value to be displayed in the input box. /// </summary> /// <param name="m"></param> public string AskStringQuestion(string msg, string default_value) { string Result = null; InputBox w = new InputBox(); MakeChild(w); if (w.ShowDialog(msg, default_value).Value) Result = w.Value; return Result; } /// <summary> /// Sets Word window as parent of the specified window. /// </summary> /// <param name="w"></param> private static void MakeChild(System.Windows.Window w) { IntPtr HWND = Process.GetCurrentProcess().MainWindowHandle; var helper = new WindowInteropHelper(w) { Owner = HWND }; } } While some of these functions are generic (ShowMessage, AskBooleanQuestion etc.), others are specific to this project and use custom Windows. You can add more custom windows in the same fashion. The key is to keep UI-specific elements in the View layer and just expose the returned data using POCOs in the VM layer. Perform IoC Registration your interface in the View layer using this class. You can do this in your main view's constructor (after InitializeComponent() call): SimpleIoc.Default.Register<IDialogService, DialogPresenter>(); There you go. You now have access to all your dialog functionality at both VM and View layers. Your VM layer can call these functions like this: var NoTrump = ViewModelLocator.DialogService.AskBooleanQuestion("Really stop the trade war???", ""); So clean you see. The VM layer doesn't know nothing about how a Yes/No question will be presented to the user by the UI layer and can still successfully work with the returned result from the dialog.

其他免费福利

For writing unit test, you can provide a custom implementation of IDialogService in your Test project and register that class in IoC in the constructor your test class. You'll need to import some namespaces such as Microsoft.Win32 to access Open and Save dialogs. I have left them out because there is also a WinForms version of these dialogs available, plus someone might want to create their own version. Also note that some of the identifier used in DialogPresenter are names of my own windows (e.g. SettingsWindow). You'll need to either remove them from both the interface and implementation or provide your own windows. If your VM performs multi-threading, call MVVM Light's DispatcherHelper.Initialize() early in your application's life cycle. Except for DialogPresenter which is injected in the View layer, other ViewModals should be registered in ViewModelLocator and then a public static property of that type should be exposed for the View layer to consume. Something like this: public static SettingsVM Settings => SimpleIoc.Default.GetInstance<SettingsVM>(); For the most part, your dialogs should not have any code-behind for stuff like binding or setting DataContext etc. You shouldn't even pass things as constructor parameters. XAML can do that all for you, like this: <Window x:Class="YourViewNamespace.SettingsWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:local="clr-namespace:YourViewProject" xmlns:vm="clr-namespace:YourVMProject;assembly=YourVMProject" DataContext="{x:Static vm:ViewModelLocator.Settings}" d:DataContext="{d:DesignInstance Type=vm:SettingsVM}" /> Setting DataContext this way gives you all kinds of design-time benefits such as Intellisense and auto-completion.

希望这对大家都有帮助。

一个好的MVVM对话框应该:

仅用XAML声明。 从数据绑定中获取它的所有行为。

不幸的是，WPF不提供这些特性。显示对话框需要对ShowDialog()进行代码隐藏调用。支持对话框的Window类不能在XAML中声明，因此它不能轻易地绑定到DataContext。

为了解决这个问题，我写了一个XAML存根控件，它位于逻辑树中，将数据绑定传递给一个Window，并处理显示和隐藏对话框的问题。你可以在这里找到它:http://www.codeproject.com/KB/WPF/XAMLDialog.aspx

它使用起来非常简单，不需要对ViewModel进行任何奇怪的更改，也不需要事件或消息。基本调用如下所示:

<dialog:Dialog Content="{Binding Path=DialogViewModel}" Showing="True" />

您可能希望添加一个设置显示的样式。我在我的文章中解释过。我希望这对你有所帮助。