Model-View-ViewModel(MVVM) with MEF

今天看David Wynne 写的一篇如果在MVVM中使用MEF进行扩展的文章，总的来说例子写的很好，可是有一个很命的地方，View是硬编码(hardcoded)到Main window中的，我就借花献佛，把它的例子稍稍改一下，以使它真正的好扩展。

 

基本上改动不大，直接贴代码吧

App.cs 

   
     

    
      
    
       
    
      public
    
       
    
      partial
    
       
    
      class
    
       App : Application
 {
 
    
      private
    
       
    
      static
    
       CompositionContainer _container;

 
    
      internal
    
       
    
      static
    
       CompositionContainer Container
 {
 
    
      get
    
      
 {
 
    
      return
    
       _container;
 }
 }
 
 [Import(
    
      "
    
      MainWindow
    
      "
    
      )]
 
    
      public
    
       
    
      new
    
       Window MainWindow
 {
 
    
      get
    
       { 
    
      return
    
       
    
      base
    
      .MainWindow; }
 
    
      set
    
       { 
    
      base
    
      .MainWindow 
    
      =
    
       value; }
 }

 
    
      protected
    
       
    
      override
    
       
    
      void
    
       OnStartup(StartupEventArgs e)
 {
 
    
      base
    
      .OnStartup(e);
 var catalog 
    
      =
    
       
    
      new
    
       AggregateCatalog();
 catalog.Catalogs.Add(
    
      new
    
       AssemblyCatalog(Assembly.GetExecutingAssembly()));
 
    
      //
    
      catalog.Catalogs.Add(new DirectoryCatalog("Extensions"));
    
      

    
       _container 
    
      =
    
       
    
      new
    
       CompositionContainer(catalog);

 var batch 
    
      =
    
       
    
      new
    
       CompositionBatch();
 batch.AddPart(
    
      this
    
      );

 
    
      try
    
      
 {
 _container.Compose(batch);
 MainWindow.Show();
 }
 
    
      catch
    
      
 {
 Shutdown();
 }
 
 }
 }
   
     

 

下面是对应的MainWindow.Xaml

 

   
     

    
      
    
      <
    
      Window 
    
      x:Class
    
      ="WpfApplication1.MainWindow"
    
      
 xmlns
    
      ="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    
      
 xmlns:x
    
      ="http://schemas.microsoft.com/winfx/2006/xaml"
    
       
 Loaded
    
      ="Window_Loaded"
    
      
 Title
    
      ="MainWindow"
    
      >
    
      
 
    
      <
    
      StackPanel 
    
      x:Name
    
      ="WidgetsPanel"
    
      ></
    
      StackPanel
    
      >
    
      

    
      </
    
      Window
    
      >
   
     

MainWindow.xaml.cs

 

代码

   
     

    
      
    
      [Export(
    
      "
    
      MainWindow
    
      "
    
      , 
    
      typeof
    
      (Window))]
 
    
      public
    
       
    
      partial
    
       
    
      class
    
       MainWindow : Window
 {
 
    
      public
    
       MainWindow()
 {
 InitializeComponent();
 }

 [ImportMany(
    
      "
    
      wpf1app
    
      "
    
      , 
    
      typeof
    
      (UIElement))]
 
    
      public
    
       Lazy
    
      <
    
      UIElement
    
      >
    
      [] Widgets { 
    
      get
    
      ; 
    
      set
    
      ; }

 
    
      private
    
       
    
      void
    
       Window_Loaded(
    
      object
    
       sender, RoutedEventArgs e)
 {
 
    
      foreach
    
       (var widget 
    
      in
    
       Widgets)
 {
 
    
      this
    
      .WidgetsPanel.Children.Add(widget.Value);
 }
 }
 }
   
     

 

Widget1.Xaml

 

   
     

    
      
    
      <
    
      UserControl x:Class
    
      =
    
      "
    
      WpfApplication1.Component1
    
      "
    
      
 xmlns
    
      =
    
      "
    
      http://schemas.microsoft.com/winfx/2006/xaml/presentation
    
      "
    
      
 xmlns:x
    
      =
    
      "
    
      http://schemas.microsoft.com/winfx/2006/xaml
    
      "
    
      
 xmlns:mc
    
      =
    
      "
    
      http://schemas.openxmlformats.org/markup-compatibility/2006
    
      "
    
       
 xmlns:d
    
      =
    
      "
    
      http://schemas.microsoft.com/expression/blend/2008
    
      "
    
       
 Loaded
    
      =
    
      "
    
      UserControl_Loaded
    
      "
    
      
 
    
      >
    
      
 
    
      <
    
      Grid
    
      >
    
      
 
    
      <
    
      Button Content
    
      =
    
      "
    
      {Binding Path=Content}
    
      "
    
       Background
    
      =
    
      "
    
      {Binding Path=BackgroudColor}
    
      "
    
       
    
      />
    
      
 
    
      </
    
      Grid
    
      >
    
      

    
      </
    
      UserControl
    
      >
    
      

   
     

Widget1.xaml.cs

 

 

 

 

代码

   
     

    
      
    
      [Export(
    
      "
    
      wpf1app
    
      "
    
      , 
    
      typeof
    
      (UIElement))]
 
    
      public
    
       
    
      partial
    
       
    
      class
    
       Component1 : UserControl
 {
 
    
      public
    
       Component1()
 { 
 InitializeComponent();
 }
 
 [Import(
    
      typeof
    
      (Widget1ModelView))]
 
    
      public
    
       Widget1ModelView ViewModel
 {
 
    
      get
    
      ;
 
    
      private
    
       
    
      set
    
      ;
 }

 
    
      private
    
       
    
      void
    
       UserControl_Loaded(
    
      object
    
       sender, RoutedEventArgs e)
 {
 
    
      this
    
      .DataContext 
    
      =
    
       ViewModel;
 }
 }
   
     

 

 

 

Widget1ModelView

 

代码

   
     

    
      
    
       [Export(
    
      typeof
    
      (Widget1ModelView))]
 
    
      public
    
       
    
      class
    
       Widget1ModelView
 {
 
    
      public
    
       
    
      string
    
       Content
 {
 
    
      get
    
      
 {
 
    
      return
    
       
    
      "
    
      Click Me
    
      "
    
      ;
 }
 }

 
    
      public
    
       
    
      string
    
       BackgroudColor
 {
 
    
      get
    
      
 {
 
    
      return
    
       
    
      "
    
      Red
    
      "
    
      ;
 }
 }
 }