共用方式為

SoapAttributes.SoapDefaultValue 屬性

  • 參考

定義

命名空間:
System.Xml.Serialization
組件:
System.Xml.XmlSerializer.dll
組件:
System.Xml.dll
組件:
netstandard.dll

取得或設定 XML 項目或屬性的預設值。

public:
 property System::Object ^ SoapDefaultValue { System::Object ^ get(); void set(System::Object ^ value); };
public object? SoapDefaultValue { get; set; }
public object SoapDefaultValue { get; set; }
member this.SoapDefaultValue : obj with get, set
Public Property SoapDefaultValue As Object

屬性值

Object

表示 XML 項目或屬性之預設值的物件。

範例

下列範例序列化名為 Group 的類別，其中包含名為 的 GroupName 欄位。 預設值會設定 DefaultValueAttribute 為 「.NET」。 藉由不設定欄位，或將它設定為 「.NET」，該值就不會序列化 (，因為預設值已經知道) 。 此範例也會覆寫 方法中的 CreateOverrideSerializer 預設值，此方法會呼叫這個 SerializeOverride 值。 此範例會呼叫 和 SerializeOverride 方法， SerializeOriginal 並針對 GroupName 欄位設定相同的值 (「.NET ) 」。 由於覆寫，只有在呼叫 SerializeOverride 方法時，才會序列化值。

#using <System.dll>
#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Xml::Serialization;
using namespace System::Xml::Schema;
using namespace System::ComponentModel;
public ref class Group
{
public:

   // The default is set to .NET.

   [DefaultValue(".NET")]
   String^ GroupName;
};

public ref class Run
{
public:
   void SerializeOriginal( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ mySerializer = gcnew XmlSerializer( Group::typeid );

      // Writing the file requires a TextWriter.
      TextWriter^ writer = gcnew StreamWriter( filename );

      // Create an instance of the class that will be serialized.
      Group^ myGroup = gcnew Group;

      // Setting the GroupName to '.NET' is like not setting it at all
      // because it is the default value. So no value will be 
      // serialized, and on deserialization it will appear as a blank.
      myGroup->GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      mySerializer->Serialize( writer, myGroup );
      writer->Close();
   }

   void SerializeOverride( String^ filename )
   {
      // Create an instance of the XmlSerializer class
      // that overrides the serialization.
      XmlSerializer^ overRideSerializer = CreateOverrideSerializer();

      // Writing the file requires a TextWriter.
      TextWriter^ writer = gcnew StreamWriter( filename );

      // Create an instance of the class that will be serialized.
      Group^ myGroup = gcnew Group;

      // The  specifies that the default value is now 
      // 'Team1'. So setting the GroupName to '.NET' means
      // the value will be serialized.
      myGroup->GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      overRideSerializer->Serialize( writer, myGroup );
      writer->Close();
   }

   void DeserializeOriginal( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ mySerializer = gcnew XmlSerializer( Group::typeid );

      // Reading the file requires a TextReader.
      TextReader^ reader = gcnew StreamReader( filename );

      // Deserialize and cast the Object*.
      Group^ myGroup;
      myGroup = safe_cast<Group^>(mySerializer->Deserialize( reader ));
      Console::WriteLine( myGroup->GroupName );
      Console::WriteLine();
   }

   void DeserializeOverride( String^ filename )
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer^ overRideSerializer = CreateOverrideSerializer();

      // Reading the file requires a TextReader.
      TextReader^ reader = gcnew StreamReader( filename );

      // Deserialize and cast the Object*.
      Group^ myGroup;
      myGroup = safe_cast<Group^>(overRideSerializer->Deserialize( reader ));
      Console::WriteLine( myGroup->GroupName );
   }

private:
   XmlSerializer^ CreateOverrideSerializer()
   {
      SoapAttributeOverrides^ mySoapAttributeOverrides = gcnew SoapAttributeOverrides;
      SoapAttributes^ soapAtts = gcnew SoapAttributes;

      // Create a new DefaultValueAttribute Object* for the GroupName
      // property.
      DefaultValueAttribute^ newDefault = gcnew DefaultValueAttribute( "Team1" );
      soapAtts->SoapDefaultValue = newDefault;
      mySoapAttributeOverrides->Add( Group::typeid, "GroupName", soapAtts );

      // Create an XmlTypeMapping that is used to create an instance 
      // of the XmlSerializer. Then return the XmlSerializer Object*.
      XmlTypeMapping^ myMapping = (gcnew SoapReflectionImporter( mySoapAttributeOverrides ))->ImportTypeMapping( Group::typeid );
      XmlSerializer^ ser = gcnew XmlSerializer( myMapping );
      return ser;
   }
};

int main()
{
   Run^ test = gcnew Run;
   test->SerializeOriginal( "SoapOriginal.xml" );
   test->SerializeOverride( "mySoapAttributeOverridesideAttributes.xml" );
   test->DeserializeOriginal( "SoapOriginal.xml" );
   test->DeserializeOverride( "mySoapAttributeOverridesideAttributes.xml" );
}

using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;
using System.ComponentModel;

public class Group
{
   // The default is set to .NET.
   [DefaultValue(".NET")]
   public string GroupName;
}

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.SerializeOriginal("SoapOriginal.xml");
      test.SerializeOverride("mySoapAttributeOverridesideAttributes.xml");
      test.DeserializeOriginal("SoapOriginal.xml");
      test.DeserializeOverride("mySoapAttributeOverridesideAttributes.xml");
   }
   public void SerializeOriginal(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer mySerializer =
      new XmlSerializer(typeof(Group));

      // Writing the file requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);

      // Create an instance of the class that will be serialized.
      Group myGroup = new Group();

      // Setting the GroupName to '.NET' is like not setting it at all
      // because it is the default value. So no value will be
      // serialized, and on deserialization it will appear as a blank.
      myGroup.GroupName = ".NET";

      // Serialize the class, and close the TextWriter.
      mySerializer.Serialize(writer, myGroup);
      writer.Close();
   }

   public void SerializeOverride(string filename)
   {
      // Create an instance of the XmlSerializer class
      // that overrides the serialization.
      XmlSerializer overRideSerializer = CreateOverrideSerializer();

      // Writing the file requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);

      // Create an instance of the class that will be serialized.
      Group myGroup = new Group();

      // The override specifies that the default value is now
      // 'Team1'. So setting the GroupName to '.NET' means
      // the value will be serialized.
      myGroup.GroupName = ".NET";
      // Serialize the class, and close the TextWriter.
      overRideSerializer.Serialize(writer, myGroup);
       writer.Close();
   }

   public void DeserializeOriginal(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer mySerializer= new XmlSerializer(typeof(Group));
      // Reading the file requires a TextReader.
      TextReader reader = new StreamReader(filename);

      // Deserialize and cast the object.
      Group myGroup;
      myGroup = (Group) mySerializer.Deserialize(reader);

      Console.WriteLine(myGroup.GroupName);
      Console.WriteLine();
   }

   public void DeserializeOverride(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlSerializer overRideSerializer = CreateOverrideSerializer();
      // Reading the file requires a TextReader.
      TextReader reader = new StreamReader(filename);

      // Deserialize and cast the object.
      Group myGroup;
      myGroup = (Group) overRideSerializer.Deserialize(reader);

      Console.WriteLine(myGroup.GroupName);
   }

   private XmlSerializer CreateOverrideSerializer()
   {
      SoapAttributeOverrides mySoapAttributeOverrides =
      new SoapAttributeOverrides();
      SoapAttributes soapAtts = new SoapAttributes();
      // Create a new DefaultValueAttribute object for the GroupName
      // property.
      DefaultValueAttribute newDefault =
      new DefaultValueAttribute("Team1");
      soapAtts.SoapDefaultValue = newDefault;

      mySoapAttributeOverrides.Add(typeof(Group), "GroupName",
      soapAtts);

      // Create an XmlTypeMapping that is used to create an instance
      // of the XmlSerializer. Then return the XmlSerializer object.
      XmlTypeMapping myMapping = (new SoapReflectionImporter(
      mySoapAttributeOverrides)).ImportTypeMapping(typeof(Group));
    
      XmlSerializer ser = new XmlSerializer(myMapping);
      return ser;
   }
}

Imports System.IO
Imports System.Xml
Imports System.Xml.Serialization
Imports System.Xml.Schema
Imports System.ComponentModel

Public Class Group
   ' The default is set to .NET.
   <DefaultValue(".NET")> _
   Public GroupName As String
End Class
 
Public Class Run

   Public Shared Sub Main()
   
      Dim test As Run = new Run()
      test.SerializeOriginal("SoapOriginal.xml")
      test.SerializeOverride _
      ("mySoapAttributeOverridesideAttributes.xml")
      test.DeserializeOriginal("SoapOriginal.xml")
      test.DeserializeOverride _
      ("mySoapAttributeOverridesideAttributes.xml")
   End Sub
   
   public Sub SerializeOriginal(filename As String)
       ' Create an instance of the XmlSerializer class.
      Dim mySerializer As XmlSerializer =  _
      new XmlSerializer(GetType(Group))

      ' Writing the file requires a TextWriter.
      Dim writer As TextWriter = new StreamWriter(filename)

      ' Create an instance of the class that will be serialized.
      Dim myGroup As Group = new Group()

      ' Setting the GroupName to '.NET' is like not setting it at all
      ' because it is the default value. So no value will be 
      ' serialized, and on deserialization it will appear as a blank.
      myGroup.GroupName = ".NET"

      ' Serialize the class, and close the TextWriter.
      mySerializer.Serialize(writer, myGroup)
      writer.Close()
   End Sub

   Public Sub SerializeOverride(filename As String)
   
      ' Create an instance of the XmlSerializer class
      ' that overrides the serialization.
      Dim overRideSerializer As XmlSerializer = CreateOverrideSerializer()

      ' Writing the file requires a TextWriter.
      Dim writer As TextWriter = new StreamWriter(filename)

      ' Create an instance of the class that will be serialized.
      Dim myGroup As Group = new Group()

      ' The override specifies that the default value is now 
      ' 'Team1'. So setting the GroupName to '.NET' means
      ' the value will be serialized.
      myGroup.GroupName = ".NET"
      ' Serialize the class, and close the TextWriter.
      overRideSerializer.Serialize(writer, myGroup)
       writer.Close()

   End Sub


   Public Sub DeserializeOriginal(filename As String)
   
      ' Create an instance of the XmlSerializer class.
      Dim mySerializer As XmlSerializer = new XmlSerializer(GetType(Group))
      ' Reading the file requires a TextReader.
      Dim reader As TextReader = new StreamReader(filename)

      ' Deserialize and cast the object.
      Dim myGroup As Group = CType(mySerializer.Deserialize(reader), Group)

      Console.WriteLine(myGroup.GroupName)
      Console.WriteLine()
   End Sub

   Public Sub DeserializeOverride(filename As String)
   
      ' Create an instance of the XmlSerializer class.
      Dim overRideSerializer As XmlSerializer = CreateOverrideSerializer()
      ' Reading the file requires a TextReader.
      Dim reader As TextReader = new StreamReader(filename)

      ' Deserialize and cast the object.
      Dim myGroup As Group = CType(overRideSerializer.Deserialize(reader), Group)

      Console.WriteLine(myGroup.GroupName)

   End Sub

   Private Function CreateOverrideSerializer() As XmlSerializer 
   
      Dim mySoapAttributeOverrides As SoapAttributeOverrides  = _
      New SoapAttributeOverrides()
      Dim soapAtts As SoapAttributes = New SoapAttributes()
      ' Create a new DefaultValueAttribute object for the GroupName
      ' property.
      Dim newDefault As DefaultValueAttribute = _
      new DefaultValueAttribute("Team1")
      soapAtts.SoapDefaultValue = newDefault

     mySoapAttributeOverrides.Add(GetType(Group), "GroupName", _
     soapAtts)
      
      ' Create an XmlTypeMapping that is used to create an instance 
      ' of the XmlSerializer. Then return the XmlSerializer object.
      Dim myMapping As XmlTypeMapping = _
      (New SoapReflectionImporter( _
      mySoapAttributeOverrides)).ImportTypeMapping(GetType(Group))
    
      Dim ser As XmlSerializer = new XmlSerializer(myMapping)
      return ser
   End Function
End Class

備註

您可以藉由將屬性套用 DefaultValueAttribute 至成員來設定成員的預設值。 如果成員序列化為編碼的 SOAP 訊息，您可以建立新的 DefaultValueAttribute 、設定其 Value 屬性，並將 屬性設定 SoapDefaultValue 為 物件，以變更預設值。 SoapAttributes將 加入至 SoapAttributeOverrides 。 如需詳細資訊，請參閱 類別概 SoapAttributeOverrides 觀。

適用於

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