SerializationInfo.GetValue(String, Type) SerializationInfo.GetValue(String, Type) SerializationInfo.GetValue(String, Type) Method

Определение

Извлекает значение из хранилища SerializationInfo.Retrieves a value from the SerializationInfo store.

public:
 System::Object ^ GetValue(System::String ^ name, Type ^ type);
public object GetValue (string name, Type type);
member this.GetValue : string * Type -> obj

Параметры

name
String String String

Имя, связанное с извлекаемым значением.The name associated with the value to retrieve.

type
Type Type Type

Тип Type значения, которое требуется извлечь.The Type of the value to retrieve. Если сохраненное значение невозможно преобразовать в этот тип, система выдает InvalidCastException.If the stored value cannot be converted to this type, the system will throw a InvalidCastException.

Возвраты

Объект заданного Type, связанного с name.The object of the specified Type associated with name.

Исключения

Значение параметра name или typenull.name or type is null.

Значение, связанное с name, невозможно преобразовать в type.The value associated with name cannot be converted to type.

Элемент с указанным именем не найден в текущем экземпляре.An element with the specified name is not found in the current instance.

Примеры

В следующем примере кода показано использование GetValue метода.The following code example demonstrates the use of the GetValue method:

// 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.
   [SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter=true)]
   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
   [SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter=true)]
   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

Комментарии

Если данные, хранящиеся в SerializationInfo , имеют запрошенный тип (или один из производных от него классов), это значение возвращается напрямую.If the data stored in the SerializationInfo is of the type requested (or one of its derived classes), that value is returned directly. В противном случае вызывается метод, IFormatterConverter.Convert чтобы преобразовать его в соответствующий тип.Otherwise, IFormatterConverter.Convert is called to convert it to the appropriate type.

Значение, возвращаемое GetValue методом, всегда может быть безопасно приведено к типу, указанному type в параметре.The value returned by the GetValue method can always be safely cast to the type specified in the type parameter.

Применяется к