反序列化然后序列化时保留 Xml Xsd schemaLocation

Posted 2023-04-12

【中文标题】反序列化然后序列化时保留 Xml Xsd schemaLocation

【英文标题】：Preserve Xml Xsd schemaLocation when deserializing then serializing

【发布时间】：2021-11-28 18:50:34

【问题描述】：

我将一个 Xml 文件反序列化为一个 .NET 类，修改属性，然后序列化回同一个文件。这是 .NET 模型 (vb.net)

<XmlRoot("StationSetpoints")>
Public Class XmlStationSetpoints
    <XmlElement("Setpoint")>
    Public Property Setpoints As List(Of XmlStationSetpointsSetpoint)
End Class

<Serializable>
Public Class XmlStationSetpointsSetpoint
    <XmlElement("Point")>
    Public Property Points As List(Of XmlStationSetpointsSetpointPoint)
    ' etc...
End Class

反序列化和序列化（c#）

var settings = New XmlStationSetpoints();
var serializer = New XmlSerializer(XmlStationSetpoints);
// deserialize
using StreamReader sr = new StreamReader(path)
    settings = (XmlStationSetpoints)serializer.Deserialize(sr);
// serialize
using StreamWriter sw = new StreamWriter(path, false)
    serializer.Serialize(sw, settings);

原始 Xml 文件，包括位于 Xml 文件 xsi:schemaLocation="http://www.w3schools.com StationSetpoints.xsd" 旁边的本地架构文件（第 5 行）

<?xml version="1.0" encoding="utf-8"?>
<StationSetpoints
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xsi:schemaLocation="http://www.w3schools.com StationSetpoints.xsd">
  <Setpoint PartNumber="108022">
    <Point InstrumentName="PD Stage" Value="10"/>
  </Setpoint>
  <Setpoint PartNumber="107983">
    <Point Order="2" InstrumentName="PD Stage" Value="7.5"/>
  </Setpoint>
</StationSetpoints>

当文件被序列化时，该架构路径不包括在内

<?xml version="1.0" encoding="utf-8"?>
<StationSetpoints 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Setpoint PartNumber="108022">
    <Point Order="0" InstrumentName="PD Stage" Value="10"></Point>
  </Setpoint>
  <Setpoint PartNumber="107983">
    <Point Order="2" InstrumentName="PD Stage" Value="7.5"></Point>
  </Setpoint>
</StationSetpoints>

如何在 .NET 类中保留该架构路径，以便序列化文件包含它？

【参考方案1】：

您可以通过为此目的添加显式属性来反序列化和重新序列化xsi:schemaLocation 属性，如this answer 中所示dtb 到XmlSerialization and xsi:SchemaLocation (xsd.exe)，适当地翻译成VB .NET：

Public Partial Class XmlStationSetpoints
    <XmlAttribute("schemaLocation", Namespace:="http://www.w3.org/2001/XMLSchema-instance")>
    Public Property xsiSchemaLocation As String = "http://www.w3schools.com StationSetpoints.xsd"
End Class

演示小提琴 #1 here.

如果您想硬编码 xsi:schemaLocation 的值并使其在序列化时无条件显示，您可以使用显式实现的属性来执行此操作，如下所示：

Public Partial Class XmlStationSetpoints
    <XmlAttribute("schemaLocation", Namespace:="http://www.w3.org/2001/XMLSchema-instance")>
    Public Property xsiSchemaLocation() As String
        Get
            Return "http://www.w3schools.com StationSetpoints.xsd"
        End Get
        Set
            ' Do nothing, it's hardcoded.  A setter is required because XmlSerializer will only serialize properties with public getters and setters.
        End Set
    End Property
End Class

演示小提琴#2 here.

如果您想硬编码xsi:schemaLocation 的值，但要控制它是否出现（因为例如它应该只在XmlStationSetpoints 是XML 文件的根元素时出现），您可以使用@ 987654326@ 属性如下：

Public Partial Class XmlStationSetpoints
    <XmlAttribute("schemaLocation", Namespace:="http://www.w3.org/2001/XMLSchema-instance")>
    Public Property xsiSchemaLocation() As String
        Get
            Return "http://www.w3schools.com StationSetpoints.xsd"
        End Get
        Set
            ' Do nothing, it's hardcoded.  A setter is required because XmlSerializer will only serialize properties with public getters and setters.
        End Set
    End Property
    <XmlIgnore>
    Public Property xsiSchemaLocationSpecified() As Boolean
End Class

该属性会捕捉反序列化过程中是否遇到xsi:schemaLocation属性，并控制是否在序列化过程中发出该属性。

演示小提琴#3 here.