Question

我是MEF的新手，并开始了一个项目来测试它。我要做的是打开一个基于接口加载插件的MainForm。这些插件需要能够在它们之间交换信息，并且MainForm也应该能够与所有这些插件进行通信。所以我开始创建加载插件的MainForm。该插件只是一个包含ListBox的表单。在MainForm我有一个按钮。我希望该按钮将List（of String）发送到插件，并使用该插件在ListBox中加载List（String）。目前，当我点击MainForm按钮时，它会将列表发送到插件。但该列表未在插件ListBox中加载。为了找到问题，我在MainForm上添加了一个新按钮，以验证插件属性实际上是否包含我发送的列表（字符串）。是的，该列表包含我的所有字符串。问题需要是ListBox没有刷新？

界面的一部分：

Public Interface IPlugIn

   Property PlugInName as string
   Property Files As List(Of String)

End Interface

MainForm按钮中的代码：

    Dim currentPlugIn As Contract.API.IPlugIn

    currentPlugIn = PlugIns.Find(Function(x) x.PlugInName = "Test")

    currentPlugIn.Files = IO.Directory.GetFiles("SomeFolder").ToList

插件中的代码：

<Export(GetType(Contract.API.IPlugIn))> _
Public Class UserControl1
   Implements System.ComponentModel.INotifyPropertyChanged, Contract.API.IPlugIn

Public Property Files As System.Collections.Generic.List(Of String) Implements
   Contract.API.IPlugIn.Files
    Get
        If IsNothing(_files) Then
            _files = New List(Of String)
        End If

        Return _files
    End Get
    Set(value As System.Collections.Generic.List(Of String))
        _files = value

        OnPropertyChanged("Files")
    End Set
End Property

Public Event PropertyChanged(sender As Object, e As 
   System.ComponentModel.PropertyChangedEventArgs) Implements
   System.ComponentModel.INotifyPropertyChanged.PropertyChanged

Public Sub OnPropertyChanged(propertyName As String)
    RaiseEvent PropertyChanged(Me, New 
    ComponentModel.PropertyChangedEventArgs(propertyName))
End Sub

PlugIn XAML中的代码：

<ListBox Name="lstFiles" ItemsSource="{Binding Path=Files}"/>

有什么问题？我在互联网上搜索了一些例子，发现了数百个，但没有一个显示如何做我想做的事情。就在我在这里发布我的问题之前，我添加了INotifyPropertyChanged，它没有解决问题。使用PRISM，Caliburn.Micro或MEF只会更好吗？

感谢您的帮助！

Answer 1

谢谢大家！

我终于找到了答案。

我实施了PRISM EventAggregator并确实更改了以下内容

在Interface and PlugIns中

完全删除

Public ReadOnly Property PlugInUI As System.Windows.Controls.UserControl Implements 
Contract.API.IPlugIn.PlugInUI
   Get
      Dim myUI As New UserControl1

      Return myUI
   End Get
End Property

在主持人

中

更改

Public Sub OnImportsSatisfied() Implements 
System.ComponentModel.Composition.IPartImportsSatisfiedNotification.OnImportsSatisfied
    For Each plugInItem In WidgetList
        Desktop.Children.Add(plugInItem.PlugInView)
    Next
End Sub

到

Public Sub OnImportsSatisfied() Implements 
System.ComponentModel.Composition.IPartImportsSatisfiedNotification.OnImportsSatisfied
    For Each plugInItem In WidgetList
        Desktop.Children.Add(plugInItem)
    Next
End Sub

现在一切都按我想要的方式运作了！

Answer 2

Athari，谢谢你的评论。

我确实将属性修复为ObservableCollection，但没有解决问题。似乎我错过了其他的东西。

这是完整的代码。

接口

Namespace API

   Public Interface IPlugIn

      Property Files As System.Collections.ObjectModel.ObservableCollection(Of String)
      ReadOnly Property PlugInUI As System.Windows.Controls.UserControl

   End Interface

End Namespace

的PlugIn

Imports System.ComponentModel.Composition

<Export(GetType(Contract.API.IPlugIn))> _
Public Class UserControl1
Implements Contract.API.IPlugIn, System.ComponentModel.INotifyPropertyChanged, 
   System.Collections.Specialized.INotifyCollectionChanged

Private _files As System.Collections.ObjectModel.ObservableCollection(Of String)

Public Property Files As System.Collections.ObjectModel.ObservableCollection(Of String)     
  Implements Contract.API.IPlugIn.Files
    Get
        If IsNothing(_files) Then
            _files = New System.Collections.ObjectModel.ObservableCollection(Of String)
        End If
        Return _files
    End Get
    Set(value As System.Collections.ObjectModel.ObservableCollection(Of String))
        _files = value
        OnPropertyChanged("Files")
        OnCollectionChanged(New 
          Collections.Specialized.NotifyCollectionChangedEventArgs _
          (Specialized.NotifyCollectionChangedAction.Reset))
    End Set
End Property

Public ReadOnly Property PlugInUI As System.Windows.Controls.UserControl Implements 
Contract.API.IPlugIn.PlugInUI
    Get
        Dim myUI As New UserControl1

        Return myUI
    End Get
End Property

Public Event PropertyChanged(sender As Object, e As 
    System.ComponentModel.PropertyChangedEventArgs) Implements      
    System.ComponentModel.INotifyPropertyChanged.PropertyChanged

Public Sub OnPropertyChanged(Optional propertyName As String = Nothing)
    RaiseEvent PropertyChanged(Me, New 
      ComponentModel.PropertyChangedEventArgs(propertyName))
End Sub

Public Event CollectionChanged(sender As Object, e As 
  System.Collections.Specialized.NotifyCollectionChangedEventArgs) Implements 
  System.Collections.Specialized.INotifyCollectionChanged.CollectionChanged

Public Sub OnCollectionChanged(args As 
  System.Collections.Specialized.NotifyCollectionChangedEventArgs)
    RaiseEvent CollectionChanged(Me, args)
End Sub

End Class

PlugIn XAML

<Grid>
    <ListBox Height="248" HorizontalAlignment="Left" Margin="30,31,0,0" Name="ListBox1" 
     VerticalAlignment="Top" Width="241" ItemsSource="{Binding Files}">
</Grid>

主机应用

Imports System.ComponentModel.Composition
Imports System.ComponentModel.Composition.Hosting

Public Class HostApp

<ImportMany(GetType(Contract.API.IPlugIn))> _
Public Property PlugIns As List(Of Contract.API.IPlugIn)
Private _container As CompositionContainer

Public Sub Compose()
    Dim catalog As New AggregateCatalog

    catalog.Catalogs.Add(New DirectoryCatalog("pluginfolder"))

    _container = New CompositionContainer(catalog)

    _container.ComposeParts(Me)
End Sub

Public Sub LoadPlugIns()
    Compose()

    For Each item In PlugIns
        Desktop.Children.Add(item.PlugInUI)
    Next
End Sub

Private Sub HostApp_Loaded(sender As Object, e As System.Windows.RoutedEventArgs) 
Handles Me.Loaded
    LoadPlugIns()
End Sub

Private Sub Button1_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) 
Handles Button1.Click
    Dim fileList As New Collections.ObjectModel.ObservableCollection(Of String)

    For Each fileItem As String In IO.Directory.GetFiles("Somefolder")
        fileList.Add(fileItem)
    Next

    PlugIns.Item(0).Files = fileList
End Sub

End Class

我需要在PlugIn ListBox中列出Files属性。

再次感谢您的帮助！

MEF和PlugIn属性更新

2 个答案: