按名称调用外部用户控件

Question

我有一个面板 (Panel1)、两个组合框 (ComboBox1、ComboBox2) 和一个按钮 (Button1)，所有这些都采用相同的形式 (Form1)。

当按钮被点击时：

Private Sub Button1_Click(sender As Object, e As EventArgs)
   Dim a as String = ComboBox1.SelectedValue() & Combobox2.SelectedValue()
   AddUserControl(a)
End Sub

a 的值是外部用户控件的名称，例如 p1k1。 我可以使用以下方法在Form1 中添加一个名为p1k1 的外部用户控件到Panel1 吗？

Private Sub AddUserControl(ByVal a As String)
    Panel1.Controls.Add(a)
End Sub

我应该怎么做才能完成这项工作？

通常我会使用：

Panel1.Controls.Add(new p1k1)

Answer 1

我终于找到了答案……

Private Sub AddUserControl(ByVal 作为字符串)
将 nmspace 调暗为 String = "mynamespace"
Dim t As Type = Assembly.GetExecutingAssembly().GetType(nmspace & "." & a)
Dim o As Control = Activator.CreateInstance(t)
Panel1.Controls.Add(o)
结束子

Answer 2

您需要使用reflection 来执行此操作。像这样的：

    Private Sub AddUserControl(ByVal a As String)
        Dim controlType As Type = Type.GetType(a)
        If controlType Is Nothing Then
            Throw New ArgumentException(String.Format("""{0}"" is not a valid type.  Type names are case sensitive.", a))
        ElseIf Not controlType.IsSubclassOf(GetType(Control)) Then
            Throw New ArgumentException(String.Format("""{0}"" does not inherit from Control.  Only Controls can be added to the control collection.", a))
        End If

        Dim newControl As Control = Activator.CreateInstance(controlType)
        If newControl Is Nothing Then
            Throw New ArgumentException(String.Format("Unspecified error when creating control of type ""{0}"".", a))
        End If
        Panel1.Controls.Add(newControl)
    End Sub