也许这个问题似乎没有任何意义，但只是因为这个问题：ObjectListView cast exception (for hit testing)
我想知道在执行时是否有一种方法可以将 aListViewItem转换为具有预定义函数的预定义类，该函数将返回 Item 和子项以将其添加到ObjectListView控件中。
像这样的东西：
Dim LVI As New ListViewItem("My Item")
LVI.SubItems.AddRange({"My SubItem 1", "My SubItem 2"})
Dim OwnType = ' ListViewItem transformed into a own type.
FastObjectListView1.SetObjects(OwnType.GET())
可以在这里看到@Mur Haf的答案如何将新项目添加到 ObjectListView？为了理解我正在尝试做的事情，我只想自动进行动态转换，而无需编写 Class 只是为了在ObjectListview.
假设预定义的类是例如模型示例song，来自OLV 站点：
Public Class Song
Public Sub New()
Me.New(String.Empty, DateTime.Now, 0)
End Sub
Public Sub New(title As String, lastPlayed As DateTime, rating As Integer)
Me.Title = title
Me.LastPlayed = lastPlayed
Me.Rating = rating
End Sub
Public Property Title() As String
Public Property LastPlayed() As DateTime
Public Property Rating() As Integer
Public Function GetSizeInMb() As Single
Return 1.2
End Function
End Class
以下假设ListViewItem已填充：
请注意，OLV 方法SetObjects接受一个IEnumerable对象，因此我们将返回一个List(T)对象。（与 OP 中链接的“Get”方法相同。）现在，将这些扩展方法添加到Module.
Public Module MyExtensions
<System.Runtime.CompilerServices.Extension()> _
Public Function ToSong(item As ListViewItem) As Song
Dim title As String = item.SubItems(0).Text
'Dim GetSizeInMb() As Single = Single.Parse(item.SubItems(1).Text) < -Skip, It 's a function in this example.
Dim lastPlayed = DateTime.Parse(item.SubItems(2).Text)
Dim rating = Integer.Parse(item.SubItems(3).Text)
Return New Song(title, lastPlayed, rating)
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](view As ListView) As List(Of Song)
Dim list As New List(Of Song)
For Each item As ListViewItem In view.Items
list.Add(item.ToSong())
Next
Return list
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](collection As IEnumerable(Of ListViewItem)) As List(Of Song)
Dim list As New List(Of Song)
For Each item As ListViewItem In collection
list.Add(item.ToSong())
Next
Return list
End Function
End Module
用法：
单人ListViewItem：
Dim item As ListViewItem = 'Some listviewitem
Me.olvSongs.SetObjects({item.ToSong()})
多个ListViewItem：
Dim item1 As ListViewItem = 'Some listviewitem
Dim item2 As ListViewItem = 'Some listviewitem
Dim item3 As ListViewItem = 'Some listviewitem
Me.olvSongs.SetObjects({item1, item2, item3}.[Get]())
或包含在 a 中的所有项目ListView：
Dim view As ListView = 'Some listview
Me.olvSongs.SetObjects(view.[Get]())
选项 2 - “接口方式”
下一个选项更具动态性。通过在您的预定义类中实现接口IMergable(T)，所有人都将支持该Get方法。
Public Interface IMergable(Of T)
Sub Merge(item As T)
End Interface
Public Module MyExtensions
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](Of T)(item As ListViewItem) As List(Of T)
Dim list As New List(Of T)
Dim obj As T = Activator.CreateInstance(Of T)()
If (GetType(T).IsAssignableFrom(GetType(IMergable(Of ListViewItem)))) Then
DirectCast(obj, IMergable(Of ListViewItem)).Merge(item)
list.Add(obj)
End If
Return list
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](Of T)(view As ListView) As List(Of T)
Dim list As New List(Of T)
If (GetType(T).IsAssignableFrom(GetType(IMergable(Of ListViewItem)))) Then
Dim obj As T = Nothing
For Each item As ListViewItem In view.Items
obj = Activator.CreateInstance(Of T)()
DirectCast(obj, IMergable(Of ListViewItem)).Merge(item)
list.Add(obj)
Next
End If
Return list
End Function
End Module
执行：
Public Class Song
Implements IMergable(Of ListViewItem)
...
Private Sub Merge(item As ListViewItem) Implements IMergable(Of ListViewItem).Merge
If (item Is Nothing) Then
Throw New ArgumentNullException("item")
End If
Me.Title = item.SubItems(0).Text
'Me.GetSizeInMb = Single.Parse(item.SubItems(1).Text) < -Skip, It 's a function in this example.
Me.LastPlayed = DateTime.Parse(item.SubItems(2).Text)
Me.Rating = Integer.Parse(item.SubItems(3).Text)
End Sub
End Class
用法：
Me.olvSongs.SetObjects(myListView.[Get](Of Song)())
Me.olvSongs.SetObjects(myListViewItem.[Get](Of Song)())
Me.olvSongs.SetObjects(myListView.[Get](Of PreDefClassType1)())
Me.olvSongs.SetObjects(myListView.[Get](Of PreDefClassType2)())
选项 3 - “反思方式”
此示例仅支持IConvertible数据类型。
Public Module MyExtensions
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](Of T)(view As ListView, ParamArray members As String()) As List(Of T)
Dim list As New List(Of ListViewItem)
For Each item As ListViewItem In view.Items
list.Add(item)
Next
Return list.Get(Of T)(members)
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](Of T)(item As ListViewItem, ParamArray members As String()) As List(Of T)
Return New ListViewItem() {item}.Get(Of T)(members)
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function [Get](Of T)(collection As IEnumerable(Of ListViewItem), ParamArray members As String()) As List(Of T)
Dim list As New List(Of T)
Dim length As Integer = (members.Length - 1)
If (length > -1) Then
Dim type As Type = GetType(T)
Dim info As KeyValuePair(Of MemberInfo, Type)() = New KeyValuePair(Of MemberInfo, Type)(length) {}
For index As Integer = 0 To length
For Each m As MemberInfo In type.GetMember(members(index), (MemberTypes.Method Or MemberTypes.Property), (BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.DeclaredOnly))
If (m.MemberType = MemberTypes.Property) Then
With DirectCast(m, PropertyInfo)
If (.CanWrite AndAlso (.GetIndexParameters().Length = 0)) Then
info(index) = New KeyValuePair(Of MemberInfo, Type)(m, .PropertyType)
Exit For
End If
End With
ElseIf (m.MemberType = MemberTypes.Method) Then
With DirectCast(m, MethodInfo)
Dim params As ParameterInfo() = .GetParameters()
If (params.Length = 1) Then
info(index) = New KeyValuePair(Of MemberInfo, Type)(m, params(0).ParameterType)
Exit For
End If
End With
End If
Next
Next
For Each item As ListViewItem In collection
Dim obj As T = Activator.CreateInstance(Of T)()
Dim ict As Type = GetType(IConvertible)
For index As Integer = 0 To length
Dim pair As KeyValuePair(Of MemberInfo, Type) = info(index)
If (Not pair.Key Is Nothing) Then
If (ict.IsAssignableFrom(pair.Value)) Then
If (pair.Key.MemberType = MemberTypes.Property) Then
DirectCast(pair.Key, PropertyInfo).SetValue(obj, System.Convert.ChangeType(item.SubItems(index).Text, pair.Value), Nothing)
Else
DirectCast(pair.Key, MethodInfo).Invoke(obj, System.Convert.ChangeType(item.SubItems(index).Text, pair.Value))
End If
Else
'TODO: Support other data types.
'If (pair.Key.MemberType = MemberTypes.Property) Then
'DirectCast(pair.Key, PropertyInfo).SetValue(obj, item.SubItems(index).Text, Nothing)
'Else
'DirectCast(pair.Key, MethodInfo).Invoke(obj, New Object() {item.SubItems(index).Text})
'End If
End If
End If
Next
list.Add(obj)
Next
End If
Return list
End Function
End Module
用法：
Me.olvSongs.SetObjects(myListView.[Get](Of Song)("Title", "GetSizeInMb", "LastPlayed", "Rating"))
Me.olvSongs.SetObjects(myListViewItem.[Get](Of Song)("Title", "GetSizeInMb", "LastPlayed", "Rating"))
Me.olvSongs.SetObjects(myListView.[Get](Of PreDefClassType1)("Prop1", "Prop2", "Prop3"))
Me.olvSongs.SetObjects(myListView.[Get](Of PreDefClassType2)("PropA", "PropB", "PropC"))