使用MEF vb.net.net framework 4.5动态加载dll

我正在使用下面的方法在vb.net中动态加载dll我正在使用LoadPlugins方法使用AggregateCatalog在名为Extensions的目录中查找插件一切正常，我使用下面的第二个列表运行dll，因为您可以看到我在使用下面的类的延迟加载

导入System.ComponentModel.Composition 导入System.ComponentModel.Composition.Hosting

我的问题是如何正确退出dll应用程序？它是否足够简单，可以在dll中使用application.exit，或者在主应用程序结束之前，它是否仍然驻留在内存中

第一个代码列表

 Private Sub LoadPlugins()
    ' Add any initialization after the InitializeComponent() call.

    'An aggregate catalog that combines multiple catalogs
    Dim catalog = New AggregateCatalog()

    'Adds all the parts found in the same assembly as the Program class
    catalog.Catalogs.Add(New AssemblyCatalog(GetType(frmMainImports).Assembly()))

    'IMPORTANT!
    'You will need to adjust this line to match your local path!
    catalog.Catalogs.Add(New DirectoryCatalog("Extensions"))

    'Create the CompositionContainer with the parts in the catalog
    _container = New CompositionContainer(catalog)

    'Fill the imports of this object
    Try
        _container.ComposeParts(Me)
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
End Sub

Private Sub btnRunImport_Click(sender As Object, e As EventArgs) Handles btnRunImport.Click
    Try

        For Each i As Lazy(Of IImport, IMetaName) In extensions

            'Search for matching extension name then invoke MyMethod in that extension then
            'set textbox1.text to the return value
            If i.Metadata.MyName = lbPlugins.SelectedItem Then txtDescription.Text = i.Value.Import("Hello From")


        Next

    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try

第二个代码列表

 Private Sub LoadPlugins()
    ' Add any initialization after the InitializeComponent() call.

    'An aggregate catalog that combines multiple catalogs
    Dim catalog = New AggregateCatalog()

    'Adds all the parts found in the same assembly as the Program class
    catalog.Catalogs.Add(New AssemblyCatalog(GetType(frmMainImports).Assembly()))

    'IMPORTANT!
    'You will need to adjust this line to match your local path!
    catalog.Catalogs.Add(New DirectoryCatalog("Extensions"))

    'Create the CompositionContainer with the parts in the catalog
    _container = New CompositionContainer(catalog)

    'Fill the imports of this object
    Try
        _container.ComposeParts(Me)
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
End Sub

Private Sub btnRunImport_Click(sender As Object, e As EventArgs) Handles btnRunImport.Click
    Try

        For Each i As Lazy(Of IImport, IMetaName) In extensions

            'Search for matching extension name then invoke MyMethod in that extension then
            'set textbox1.text to the return value
            If i.Metadata.MyName = lbPlugins.SelectedItem Then txtDescription.Text = i.Value.Import("Hello From")


        Next

    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try

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不太清楚“退出dll应用程序”是什么意思。DLL不是应用程序-它们是库。从DLL中调用Application.Exit将关闭主应用程序。@DeveloperGuo我想问的是，打开DLL后卸载DLL的最佳方法是什么