RAII XmlWriter VisualBasic

Question

我只是拿起VB，所以这可能是一个菜鸟问题。提前道歉。

我试图用一个类来包装一个XmlWriter来管理内存，刷新，关闭等等......这样客户就不用担心了。

我的代码是：

Option Explicit On
Option Strict Off

Imports System.Xml
Imports System.IO


Module MainModule
    Sub Main()
        Dim xmltest As XmlOutput = New XmlOutput("output.xml", "test")
        xmltest.writeData("hello", "19.95")
    End Sub
End Module

Public Class XmlOutput

    Private xmlWriter As XmlWriter

    Public Sub New(ByVal filename As String, ByVal calculator As String)
        xmlWriter = XmlWriter.Create(filename)
        xmlWriter.WriteStartDocument(True)
        xmlWriter.WriteStartElement(calculator)
    End Sub

    Protected Overrides Sub Finalize()
        xmlWriter.WriteEndElement()
        xmlWriter.WriteEndDocument()
        xmlWriter.Dispose()
    End Sub

    Public Sub writeData(ByVal head As String, ByVal value As String)
        xmlWriter.WriteElementString(head, value)
    End Sub
End Class

当我运行时，我收到以下错误：

System.ObjectDisposedException was unhandled
  HResult=-2146232798
  Message=Cannot access a closed file.
  ObjectName=""
  Source=mscorlib
  StackTrace:
       at System.IO.__Error.FileNotOpen()
       at System.IO.FileStream.Flush(Boolean flushToDisk)
       at System.IO.FileStream.Flush()
       at System.Xml.XmlUtf8RawTextWriter.Close()
       at System.Xml.XmlRawWriter.Close(WriteState currentState)
       at System.Xml.XmlWellFormedWriter.Close()
       at System.Xml.XmlWriter.Dispose(Boolean disposing)
       at System.Xml.XmlWriter.Dispose()
       at XmlOutputTest.XmlOutput.Finalize()
  InnerException: 

看起来XmlWriter在关闭XmlWriter之前关闭了FileStream。由于XmlWriter负责FileStream，我希望它知道FileStream何时关闭。

问题：

1. 为什么XmlWriter试图关闭它已经关闭的东西（或者我可能错误地解释了堆栈跟踪）？
2. 我需要做些什么来解决这个问题？