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

定义

SerializationInfo 存储中检索一个值。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

参数

name
String String String

与要检索的值关联的名称。The name associated with the value to retrieve.

type
Type Type Type

要检索的值的 TypeThe Type of the value to retrieve. 如果存储的值不能转换为此类型,则系统会引发 InvalidCastExceptionIf the stored value cannot be converted to this type, the system will throw a InvalidCastException.

返回

name 关联的已指定 Type 的对象。The object of the specified Type associated with name.

异常

nametypenullname or type is null.

name 关联的值不能转换为 typeThe value associated with name cannot be converted to type.

当前实例中没有找到具有指定名称的元素。An element with the specified name is not found in the current instance.

示例

下面的代码示例演示GetValue方法的用法: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

注解

如果存储在中SerializationInfo的数据是所请求的类型 (或其派生类之一), 则将直接返回该值。If the data stored in the SerializationInfo is of the type requested (or one of its derived classes), that value is returned directly. 否则, IFormatterConverter.Convert将调用来将其转换为适当的类型。Otherwise, IFormatterConverter.Convert is called to convert it to the appropriate type.

GetValue方法返回的值始终可以安全地强制转换为type参数中指定的类型。The value returned by the GetValue method can always be safely cast to the type specified in the type parameter.

适用于