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

定義

SerializationInfo 存放區擷取值。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

參數

name
String String String

與要擷取的值相關聯的名稱。The name associated with the value to retrieve.

type
Type Type Type

要擷取之值的 TypeThe Type of the value to retrieve. 如果儲存的值無法轉換為這個型別,則系統將擲回 InvalidCastExceptionIf the stored value cannot be converted to this type, the system will throw a InvalidCastException.

傳回

指定的 Type 的物件與 name 相關聯。The object of the specified Type associated with name.

例外狀況

nametypenullname or type is null.

name 相關聯的數值無法轉換為 typeThe value associated with name cannot be converted to type.

在目前的執行個體中找不到具有指定名稱的項目。An element with the specified name is not found in the current instance.

範例

下列程式碼範例示範使用GetValue方法: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

備註

如果資料儲存在SerializationInfo是要求的型別 (或其衍生的類別),可以直接傳回的值。If the data stored in the SerializationInfo is of the type requested (or one of its derived classes), that value is returned directly. 否則,IFormatterConverter.Convert呼叫以將它轉換成適當的型別。Otherwise, IFormatterConverter.Convert is called to convert it to the appropriate type.

所傳回的值GetValue方法可以永遠安全地轉換成在指定的型別type參數。The value returned by the GetValue method can always be safely cast to the type specified in the type parameter.

適用於