XML文本閱讀器覆寫跳過子元素-有解無憂

我有一個類似于以下內容的 XML 檔案，它是從一組模型和屬性上的 XML 注釋序列化的。

<?xml version="1.0"?>
<RootElement xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" SomeAttribute="123">
  <ChildElementList>
    <SampleElement xsi:type="SampleElementX" SampleElementSomeAttribute="456">
        <AnotherSampleElementList/>
    </SampleElement >
  </ChildElementList>
</RootElement >

我嘗試使用新創建的 POCO 結構反序列化現有 XML 檔案。

為了能夠反序列化檔案，我需要將元素和屬性名稱與我的 POCO 物件匹配，但是，更改 POCO 類的名稱和屬性不是一個選項，因此我決定在期間重命名必要的元素和屬性讀操作。

我可以毫無問題地讀取和反序列化 RootElement 的屬性。

當我使用 XML Reader 讀取 XML 檔案時，每當我到達“ChildElementList”時，代碼都會進入 Skip。但是，我還想讀取和反序列化該串列中的每個元素。為什么會發生這種情況，我該如何解決這個問題？我真的很感激一些幫助。

我有一個類似于以下的結構

XML 閱讀器覆寫

Public Class CustomTextReader
Inherits XmlTextReader
Protected ReadOnly provider As XmlReadWriteProvider

Public Sub New(input As Stream)
    MyBase.New(input)
End Sub

Public Sub New(provider As XmlReadWriteProvider, input As Stream)
    MyBase.New(input)
    Me.provider = provider
End Sub


Public Overrides Sub Skip()
    MyBase.Skip()
End Sub

Public Overrides ReadOnly Property LocalName As String
    Get
        Return GetElementName(MyBase.LocalName)
    End Get
End Property

Public Overrides ReadOnly Property Name As String
    Get
        Return GetElementName(MyBase.Name)
    End Get
End Property

Public Overrides Function GetAttribute(localName As String, namespaceURI As String) As String
    Dim att As String = MyBase.GetAttribute(localName, namespaceURI)
    Return If(att IsNot Nothing, If(att = att.EndsWith("X"), att.Replace(att.Substring(-1, 1), "POCO"), att   "POCO"), att)
End Function



Function IsExcludedNode(nodeName As String) As Boolean
    Return excludeNodes.Contains(nodeName)
End Function

Function GetElementName(elementName As String) As String
    If MyBase.NodeType <> XmlNodeType.Element Then Return elementName
    If IsExcludedNode(elementName) Then Return elementName
    Return elementName   "POCO"
End Function
End Class

序列化

Public Shared Function Deserialize(Of T)(fileName As String, extraTypes As Type()) As T
    Using xmlFileStream As FileStream = New FileStream(fileName, FileMode.Open)
        Using customXmlReader As XmlReader = XmlReadWriteProvider.GetXmlReader(GetType(T), xmlFileStream)
            Dim xmlSerializer As XmlSerializer = GetXmlSerializer(GetType(T), GetXmlAttributeOverrides(extraTypes), extraTypes, Nothing, Nothing)
            Deserialize = CType(xmlSerializer.Deserialize(customXmlReader), T)
        End Using
    End Using
    Return Deserialize
End Function


Shared Function GetXmlSerializer(type As Type, [overrides] As XmlAttributeOverrides, extraTypes() As Type, root As XmlRootAttribute, defaultNamespace As String) As XmlSerializer
    Dim customXmlSerializer As XmlSerializer = Nothing
    customXmlSerializer = New XmlSerializer(type, [overrides], extraTypes, root, defaultNamespace)
    Return customXmlSerializer
End Function

'Add XML attribute tag to the properties of all known extra types.
Private Shared Function GetXmlAttributeOverrides(extraTypes As Type()) As XmlAttributeOverrides
    Dim xmlAttributeOverrides = New XmlAttributeOverrides
    For Each type In extraTypes
        AddAttributeOverrides(type, xmlAttributeOverrides)
    Next
    Return xmlAttributeOverrides
End Function

Private Shared Sub AddAttributeOverrides(type As Type, xmlAttributeOverrides As XmlAttributeOverrides)
    For Each propertyInfo In type.GetProperties
        xmlAttributeOverrides.Add(type, propertyInfo.Name, GetXmlAttribute(propertyInfo))
    Next
End Sub

'If object is a primitive type it's an attribute, if it's a list it's an element
Shared Function GetXmlAttribute(propertyInfo As PropertyInfo) As XmlAttributes
    If propertyInfo.IsPrimitive() Then
        Return New XmlAttributes With {.XmlAttribute = New XmlAttributeAttribute With {.AttributeName = propertyInfo.Name}}
    End If
    If GetType(IEnumerable).IsAssignableFrom(propertyInfo.PropertyType) Then
        Return New XmlAttributes With {.XmlArray = New XmlArrayAttribute With {.ElementName = propertyInfo.Name}}
    End If
    Return New XmlAttributes
End Function

<System.Runtime.CompilerServices.Extension>
Private Function IsPrimitiveInternal(t As Type) As Boolean
    Return t.IsPrimitive OrElse t.IsValueType OrElse (t = GetType(String))
End Function

<System.Runtime.CompilerServices.Extension>
Function IsPrimitive(p As MemberInfo) As Boolean
    Return IsPrimitiveInternal(If(TryCast(p, PropertyInfo)?.PropertyType, p))
End Function

<System.Runtime.CompilerServices.Extension>
Public Function GetListItemType(IEnumerableType As Type) As Type
    If IEnumerableType.IsGenericType AndAlso IEnumerableType.GetGenericTypeDefinition() Is GetType(List(Of)) Then
        Return IEnumerableType.GetGenericArguments(0)
    End If
    Return Nothing
End Function

更新： 我意識到不修改元素名稱時它可以正常作業。

考慮到我的 POCO 類名是“SampleObjectPOCO”，請參見以下行

Return elementName   "POCO"

以下

Function GetElementName(elementName As String) As String
If MyBase.NodeType <> XmlNodeType.Element Then Return elementName
If IsExcludedNode(elementName) Then Return elementName
Return elementName   "POCO" 'Not Working when the XML property name is "SampleElement"
End Function

如果我的 XML 檔案具有元素名稱“SampleElementPOCO”而不是“SampleElement”，則它可以正常作業。當我在上面的行中動態更改它時，它停止作業。

Function GetElementName(elementName As String) As String
If MyBase.NodeType <> XmlNodeType.Element Then Return elementName
If IsExcludedNode(elementName) Then Return elementName
Return elementName 'Working when the XML property name is "SampleElementPOCO"
End Function

uj5u.com熱心網友回復：

最后，我發現 XmlTextReader 不支持更改 XML 元素的名稱。

我使用 Xml.Linq 將 XML 檔案讀入 XDocument 并執行以下操作

Public Shared Function XMLTransformer(filepath As String) As XDocument

    Dim doc = XDocument.Load(filepath)
    Dim xsiNameSpace As XNamespace = "http://www.w3.org/2001/XMLSchema-instance"

    For Each element As XElement In doc.Descendants
        Dim typeAttribute As XAttribute = element.Attribute(xsiNameSpace   "type")
        If typeAttribute IsNot Nothing Then
            typeAttribute.Value = If(typeAttribute.Value.EndsWith("X"), typeAttribute.Value.Replace(typeAttribute.Value.Substring(typeAttribute.Value.Length - 1, 1), "POCO"), typeAttribute.Value   "POCO")
        End If
        If element.NodeType = XmlNodeType.Element AndAlso element.Attributes.Count > 0 Then 
            element.Name = element.Name.ToString   "POCO"
        End If
    Next
End Function

然后我把它交給序列化器如下

SerializationManager.Deserialize(Of T)(SerializationHelper.GetExtraTypes,SerializationHelper.XMLTransformer(fileName))

我還創建了一個反序列化多載，如下所示

Public Shared Function Deserialize(Of T)(extraTypes As Type(), xmlContent As XDocument) As T
    Dim xmlSerializer As XmlSerializer = New XmlSerializer(GetType(T), GetXmlAttributeOverrides(extraTypes), extraTypes, Nothing, Nothing)
    Return CType(xmlSerializer.Deserialize(xmlContent.Root.CreateReader), T)
End Function

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標籤：xml VB.net 序列化 xml 解析 xml阅读器

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