為什么List（Int32）的JSON序列化為ArrayList？

Question

我正在嘗試使用JavaScriptSerializer序列化List(Of Int32) 。 在嘗試將對象Deserialize列表之前，它似乎一直有效，這時出現此錯誤：

無法將類型為“ System.Collections.ArrayList”的對象轉換為類型為“ System.Collections.Generic.List`1 [System.Int32]”。

我的代碼如下。 誰能解釋為什么即使我顯式轉換為正確的類型時，列表也自動保存為ArrayList？

提前致謝。

Private Property _serialized As String
    Get
        Return ViewState("_serialized")
    End Get
    Set(value As String)
        ViewState("_serialized") = value
    End Set
End Property

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        Dim l As New List(Of Int32) From {2, 4, 6, 8, 10}
        Dim d As New Dictionary(Of String, Object)
        d.Add("myList", l)
        Dim js As New Script.Serialization.JavaScriptSerializer
        Me._serialized = js.Serialize(d)
    End If
End Sub

Protected Sub btn_Click(sender As Object, e As EventArgs) Handles btn.Click
    Dim js As New Script.Serialization.JavaScriptSerializer
    Dim d As Dictionary(Of String, Object) = js.Deserialize(Of Dictionary(Of String, Object))(Me._serialized)
    Dim l As List(Of Int32) = CType(d.Item("myList"), List(Of Int32))
    For Each i As Int32 In l
        Trace.Warn(i.ToString)
    Next
End Sub

錯誤行是這樣的：

Dim l As List(Of Int32) = CType(d.Item("myList"), List(Of Int32))

Answer 1

JSON不存儲服務器端表示形式。 它不知道這是一個列表，因此必須通用。 但是您應該能夠執行以下操作以將其取回：

Ctype(d.Item("myList"), ArrayList).Cast(Of Integer)().ToList()