WPF MVVM：ViewModel 如何相互通信

使用 WPF (Windows Presentation Foundation) 开发应用程序时，MVVM (Model-View-ViewModel) 是一种常用的设计模式。在 MVVM 中，ViewModel 负责处理应用程序的业务逻辑和状态管理，而 View 负责向用户展示数据和处理用户输入。在实际开发中，ViewModel 之间可能需要进行相互通信，以实现某些特定的功能或数据共享。本文将介绍在 WPF MVVM 中，ViewModel 如何相互通信的几种常用方法，并提供相应的案例代码。

csharp
public class MainViewModel : INotifyPropertyChanged
{
    public event EventHandler SomethingHappened;
    private void OnSomethingHappened()
    {
        SomethingHappened?.Invoke(this, EventArgs.Empty);
    }
}

csharp
public class SubViewModel : INotifyPropertyChanged
{
    public SubViewModel(MainViewModel mainViewModel)
    {
        mainViewModel.SomethingHappened += MainViewModel_SomethingHappened;
    }
    private void MainViewModel_SomethingHappened(object sender, EventArgs e)
    {
        // 处理事件触发时的逻辑
    }
}

csharp
public class MainViewModel : INotifyPropertyChanged
{
    private readonly IEventAggregator _eventAggregator;
    public MainViewModel(IEventAggregator eventAggregator)
    {
        _eventAggregator = eventAggregator;
    }
    private void SomeMethod()
    {
        _eventAggregator.GetEvent().Publish();
    }
}

csharp
public class SubViewModel : INotifyPropertyChanged
{
    private readonly IEventAggregator _eventAggregator;
    public SubViewModel(IEventAggregator eventAggregator)
    {
        _eventAggregator = eventAggregator;
        _eventAggregator.GetEvent().Subscribe(OnSomeEvent);
    }
    private void OnSomeEvent()
    {
        // 处理事件触发时的逻辑
    }
}

csharp
public class MainViewModel : INotifyPropertyChanged
{
    private readonly SharedDataModel _sharedDataModel;
    public MainViewModel(SharedDataModel sharedDataModel)
    {
        _sharedDataModel = sharedDataModel;
    }
    private void SomeMethod()
    {
        _sharedDataModel.SomeProperty = "New Value";
    }
}

csharp
public class SubViewModel : INotifyPropertyChanged
{
    private readonly SharedDataModel _sharedDataModel;
    public SubViewModel(SharedDataModel sharedDataModel)
    {
        _sharedDataModel = sharedDataModel;
    }
    private void SomeOtherMethod()
    {
        var value = _sharedDataModel.SomeProperty;
        // 使用共享的数据模型进行操作
    }
}