SerializationInfo.GetValue(String, Type) Metodo

Definizione

Spazio dei nomi:

System.Runtime.Serialization

Assembly:

System.Runtime.dll

Assembly:

System.Runtime.Serialization.Formatters.dll

Assembly:

mscorlib.dll

Assembly:

netstandard.dll

Recupera un valore dall'archivio SerializationInfo.

public:
 System::Object ^ GetValue(System::String ^ name, Type ^ type);

public object? GetValue (string name, Type type);

public object GetValue (string name, Type type);

member this.GetValue : string * Type -> obj

Public Function GetValue (name As String, type As Type) As Object

Parametri

name

String

Nome associato al valore da recuperare.

type

Type

Tipo Type del valore da recuperare. Se il valore memorizzato non può essere convertito in questo tipo, verrà generata un'eccezione InvalidCastException.

Restituisce

Object

Oggetto del tipo Type specificato associato a name.

Eccezioni

ArgumentNullException

name o type è null.

InvalidCastException

Il valore associato a name non può essere convertito in type.

SerializationException

Non è possibile trovare un elemento con il nome specificato nell'istanza corrente.

Esempio

Nell'esempio di codice seguente viene illustrato l'uso del GetValue metodo :

// A serializable LinkedList example.  For the full LinkedList implementation
// see the Serialization sample.
[Serializable]
ref class LinkedList: public ISerializable
{
private:
   Node^ m_head;
   Node^ m_tail;

   // Serializes the object.
public:
   virtual void GetObjectData( SerializationInfo^ info, StreamingContext /*context*/ )
   {
      // Stores the m_head and m_tail references in the SerializationInfo info.
      info->AddValue( "head", m_head, m_head->GetType() );
      info->AddValue( "tail", m_tail, m_tail->GetType() );
   }

   // Constructor that is called automatically during deserialization.
private:
   // Reconstructs the object from the information in SerializationInfo info
   LinkedList( SerializationInfo^ info, StreamingContext /*context*/ )
   {
      Node^ temp = gcnew Node( 0 );
      // Retrieves the values of Type temp.GetType() from SerializationInfo info
      m_head = dynamic_cast<Node^>(info->GetValue( "head", temp->GetType() ));
      m_tail = dynamic_cast<Node^>(info->GetValue( "tail", temp->GetType() ));
   }
};

// A serializable LinkedList example.  For the full LinkedList implementation
// see the Serialization sample.
[Serializable()]
class LinkedList: ISerializable {

   public static void Main() {}

   Node m_head = null;
   Node m_tail = null;

   // Serializes the object.
   public void GetObjectData(SerializationInfo info, StreamingContext context){
      // Stores the m_head and m_tail references in the SerializationInfo info.
      info.AddValue("head", m_head, m_head.GetType());
      info.AddValue("tail", m_tail, m_tail.GetType());
   }

   // Constructor that is called automatically during deserialization.
   // Reconstructs the object from the information in SerializationInfo info
   private LinkedList(SerializationInfo info, StreamingContext context)
   {
      Node temp = new Node(0);
      // Retrieves the values of Type temp.GetType() from SerializationInfo info
      m_head = (Node)info.GetValue("head", temp.GetType());
      m_tail = (Node)info.GetValue("tail", temp.GetType());
   }
}

' A serializable LinkedList example.  For the full LinkedList implementation
' see the Serialization sample.
<Serializable()> Class LinkedList
    Implements ISerializable

    Public Shared Sub Main()
    End Sub

    Private m_head As Node = Nothing
    Private m_tail As Node = Nothing    
    
    ' Serializes the object.
    Public Sub GetObjectData(info As SerializationInfo, _
    context As StreamingContext) Implements ISerializable.GetObjectData
    
        ' Stores the m_head and m_tail references in the SerializationInfo info.
        info.AddValue("head", m_head, m_head.GetType())
        info.AddValue("tail", m_tail, m_tail.GetType())
    End Sub
    
    
    ' Constructor that is called automatically during deserialization.
    ' Reconstructs the object from the information in SerializationInfo info.
    Private Sub New(info As SerializationInfo, context As StreamingContext)
        Dim temp As New Node(0)
        ' Retrieves the values of Type temp.GetType() from SerializationInfo info.
        m_head = CType(info.GetValue("head", temp.GetType()), Node)
        m_tail = CType(info.GetValue("tail", temp.GetType()), Node)
    End Sub
End Class

Commenti

Se i dati archiviati in SerializationInfo sono del tipo richiesto (o una delle relative classi derivate), tale valore viene restituito direttamente. In caso contrario, IFormatterConverter.Convert viene chiamato per convertirlo nel tipo appropriato.

Il valore restituito dal GetValue metodo può essere sempre sottoposto a cast sicuro al tipo specificato nel type parametro .