我有一个小型项目,其中包含一个名为的单例类ViewFinder
,它有几个名为MakeWindowFor(vm)
and的静态方法MakeDialogFor(vm)
,它们都将视图模型作为参数。ViewFinder
有一个我填写的字典,它将视图模型与我设置为对应于它们的窗口链接起来。可以添加更多信息,因为视图可能存在于另一个视图中,而不仅仅是一个窗口。
这可能不是完成任务的最佳方式,但可以满足我对这个项目的需求,并使视图模型不知道实际的视图实现。我所有的视图模型的祖先都包含显示消息框等事件,我所有的窗口都来自一个知道如何订阅和响应这些常见事件的基类。
public class ViewFinder {
private static ViewFinder m_Instance;
public static ViewFinder Instance {
get {
if (m_Instance == null)
m_Instance = new ViewFinder();
return (m_Instance);
}
}
/// Maps viewmodels to windows/dialogs. The key is the type of the viewmodel, the value is the type of the window.
private Dictionary<Type, Type> ViewDictionary = new Dictionary<Type, Type>();
/// Private constructor because this is a singleton class.
///
/// Registers the viewmodels/views.
private ViewFinder() {
Register(typeof(SomeViewModel), typeof(SomeWindowsForViewModel));
Register(typeof(SomeViewModel2), typeof(SomeWindowsForViewModel2));
}
/// Registers a window with a viewmodel for later lookup.
/// <param name="viewModelType">The Type of the viewmodel. Must descend from ViewModelBase.</param>
/// <param name="windowType">The Type of the view. Must descend from WindowBase.</param>
public void Register(Type viewModelType, Type windowType) {
if (viewModelType == null)
throw new ArgumentNullException("viewModelType");
if (windowType == null)
throw new ArgumentNullException("windowType");
if (!viewModelType.IsSubclassOf(typeof(ViewModelBase)))
throw new ArgumentException("viewModelType must derive from ViewModelBase.");
if (!windowType.IsSubclassOf(typeof(WindowBase)))
throw new ArgumentException("windowType must derive from WindowBase.");
ViewDictionary.Add(viewModelType, windowType);
}
/// Finds the window registered for the viewmodel and shows it in a non-modal way.
public void MakeWindowFor(ViewModelBase viewModel) {
Window win = CreateWindow(viewModel);
win.Show();
}
/// Finds a window for a viewmodel and shows it with ShowDialog().
public bool? MakeDialogFor(ViewModelBase viewModel) {
Window win = CreateWindow(viewModel);
return (win.ShowDialog());
}
/// Helper function that searches through the ViewDictionary and finds a window. The window is not shown here,
/// because it might be a regular non-modal window or a dialog.
private Window CreateWindow(ViewModelBase viewModel) {
Type viewType = ViewDictionary[viewModel.GetType()] as Type;
if (viewType == null)
throw new Exception(String.Format("ViewFinder can't find a view for type '{0}'.", viewModel.GetType().Name));
Window win = Activator.CreateInstance(viewType) as Window;
if (win == null)
throw new Exception(String.Format("Activator returned null while trying to create instance of '{0}'.", viewType.Name));
win.DataContext = viewModel;
return win;
}
}