IObjectReference.GetRealObject(StreamingContext) Metoda
Definicja
Ważne
Niektóre informacje odnoszą się do produktu w wersji wstępnej, który może zostać znacząco zmodyfikowany przed wydaniem. Firma Microsoft nie udziela żadnych gwarancji, jawnych lub domniemanych, w odniesieniu do informacji podanych w tym miejscu.
Zwraca rzeczywisty obiekt, który powinien być deserializowany, a nie obiekt, który określa serializowany strumień.
public:
System::Object ^ GetRealObject(System::Runtime::Serialization::StreamingContext context);
public object GetRealObject (System.Runtime.Serialization.StreamingContext context);
[System.Security.SecurityCritical]
public object GetRealObject (System.Runtime.Serialization.StreamingContext context);
abstract member GetRealObject : System.Runtime.Serialization.StreamingContext -> obj
[<System.Security.SecurityCritical>]
abstract member GetRealObject : System.Runtime.Serialization.StreamingContext -> obj
Public Function GetRealObject (context As StreamingContext) As Object
Parametry
- context
- StreamingContext
Obiekt StreamingContext , z którego bieżący obiekt jest deserializowany.
Zwraca
Rzeczywisty obiekt umieszczony na grafie.
- Atrybuty
Wyjątki
Obiekt wywołujący nie posiada wymaganych uprawnień. Wywołanie nie będzie działać na średnim zaufanym serwerze.
Przykłady
using namespace System;
using namespace System::IO;
using namespace System::Collections;
using namespace System::Runtime::Serialization::Formatters::Binary;
using namespace System::Runtime::Serialization;
ref class SingletonSerializationHelper;
// There should be only one instance of this type per AppDomain.
[Serializable]
public ref class Singleton sealed: public ISerializable
{
private:
// This is the one instance of this type.
static Singleton^ theOneObject = gcnew Singleton;
public:
// Here are the instance fields.
String^ someString;
Int32 someNumber;
private:
// Private constructor allowing this type to construct the singleton.
Singleton()
{
// Do whatever is necessary to initialize the singleton.
someString = "This is a String* field";
someNumber = 123;
}
public:
// A method returning a reference to the singleton.
static Singleton^ GetSingleton()
{
return theOneObject;
}
// A method called when serializing a Singleton.
[System::Security::Permissions::SecurityPermissionAttribute
(System::Security::Permissions::SecurityAction::LinkDemand,
Flags=System::Security::Permissions::SecurityPermissionFlag::SerializationFormatter)]
virtual void GetObjectData( SerializationInfo^ info, StreamingContext context )
{
// Instead of serializing this Object*, we will
// serialize a SingletonSerializationHelp instead.
info->SetType( SingletonSerializationHelper::typeid );
// No other values need to be added.
}
// NOTE: ISerializable*'s special constructor is NOT necessary
// because it's never called
};
[Serializable]
private ref class SingletonSerializationHelper sealed: public IObjectReference
{
public:
// This Object* has no fields (although it could).
// GetRealObject is called after this Object* is deserialized
virtual Object^ GetRealObject( StreamingContext context )
{
// When deserialiing this Object*, return a reference to
// the singleton Object* instead.
return Singleton::GetSingleton();
}
};
[STAThread]
int main()
{
FileStream^ fs = gcnew FileStream( "DataFile.dat",FileMode::Create );
try
{
// Construct a BinaryFormatter and use it
// to serialize the data to the stream.
BinaryFormatter^ formatter = gcnew BinaryFormatter;
// Create an array with multiple elements refering to
// the one Singleton Object*.
array<Singleton^>^a1 = {Singleton::GetSingleton(),Singleton::GetSingleton()};
// This displays S"True".
Console::WriteLine( "Do both array elements refer to the same Object? {0}", (a1[ 0 ] == a1[ 1 ]) );
// Serialize the array elements.
formatter->Serialize( fs, a1 );
// Deserialize the array elements.
fs->Position = 0;
array<Singleton^>^a2 = (array<Singleton^>^)formatter->Deserialize( fs );
// This displays S"True".
Console::WriteLine( "Do both array elements refer to the same Object? {0}", (a2[ 0 ] == a2[ 1 ]) );
// This displays S"True".
Console::WriteLine( "Do all array elements refer to the same Object? {0}", (a1[ 0 ] == a2[ 0 ]) );
}
catch ( SerializationException^ e )
{
Console::WriteLine( "Failed to serialize. Reason: {0}", e->Message );
throw;
}
finally
{
fs->Close();
}
return 0;
}
using System;
using System.Web;
using System.IO;
using System.Collections;
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;
// There should be only one instance of this type per AppDomain.
[Serializable]
public sealed class Singleton : ISerializable
{
// This is the one instance of this type.
private static readonly Singleton theOneObject = new Singleton();
// Here are the instance fields.
private string someString_value;
private Int32 someNumber_value;
public string SomeString
{
get{return someString_value;}
set{someString_value = value;}
}
public Int32 SomeNumber
{
get{return someNumber_value;}
set{someNumber_value = value;}
}
// Private constructor allowing this type to construct the Singleton.
private Singleton()
{
// Do whatever is necessary to initialize the Singleton.
someString_value = "This is a string field";
someNumber_value = 123;
}
// A method returning a reference to the Singleton.
public static Singleton GetSingleton()
{
return theOneObject;
}
// A method called when serializing a Singleton.
void ISerializable.GetObjectData(
SerializationInfo info, StreamingContext context)
{
// Instead of serializing this object,
// serialize a SingletonSerializationHelp instead.
info.SetType(typeof(SingletonSerializationHelper));
// No other values need to be added.
}
// Note: ISerializable's special constructor is not necessary
// because it is never called.
}
[Serializable]
internal sealed class SingletonSerializationHelper : IObjectReference
{
// This object has no fields (although it could).
// GetRealObject is called after this object is deserialized.
public Object GetRealObject(StreamingContext context)
{
// When deserializing this object, return a reference to
// the Singleton object instead.
return Singleton.GetSingleton();
}
}
class App
{
[STAThread]
static void Main()
{
FileStream fs = new FileStream("DataFile.dat", FileMode.Create);
try
{
// Construct a BinaryFormatter and use it
// to serialize the data to the stream.
BinaryFormatter formatter = new BinaryFormatter();
// Create an array with multiple elements refering to
// the one Singleton object.
Singleton[] a1 = { Singleton.GetSingleton(), Singleton.GetSingleton() };
// This displays "True".
Console.WriteLine(
"Do both array elements refer to the same object? " +
(a1[0] == a1[1]));
// Serialize the array elements.
formatter.Serialize(fs, a1);
// Deserialize the array elements.
fs.Position = 0;
Singleton[] a2 = (Singleton[]) formatter.Deserialize(fs);
// This displays "True".
Console.WriteLine("Do both array elements refer to the same object? "
+ (a2[0] == a2[1]));
// This displays "True".
Console.WriteLine("Do all array elements refer to the same object? "
+ (a1[0] == a2[0]));
}
catch (SerializationException e)
{
Console.WriteLine("Failed to serialize. Reason: " + e.Message);
throw;
}
finally
{
fs.Close();
}
}
}
Imports System.Web
Imports System.IO
Imports System.Collections
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Runtime.Serialization
Imports System.Security.Permissions
' There should be only one instance of this type per AppDomain.
<Serializable()> _
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _
Public NotInheritable Class Singleton
Implements ISerializable
' This is the one instance of this type.
Private Shared ReadOnly theOneObject As New Singleton
' Here are the instance fields.
Private someString As String
private someNumber As Int32
' Private constructor allowing this type to construct the Singleton.
Private Sub New()
' Do whatever is necessary to initialize the Singleton.
someString = "This is a string field"
someNumber = 123
End Sub
' A method returning a reference to the Singleton.
Public Shared Function GetSingleton() As Singleton
Return theOneObject
End Function
' A method called when serializing a Singleton.
<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags:=SecurityPermissionFlag.SerializationFormatter)> _
Private Sub GetObjectData(ByVal info As SerializationInfo, _
ByVal context As StreamingContext) _
Implements ISerializable.GetObjectData
' Instead of serializing this object, we will
' serialize a SingletonSerializationHelp instead.
info.SetType(GetType(SingletonSerializationHelper))
' No other values need to be added.
End Sub
' Note: ISerializable's special constructor is not necessary
' because it is never called.
End Class
<Serializable()> _
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _
Friend NotInheritable Class SingletonSerializationHelper
Implements IObjectReference
' This object has no fields (although it could).
' GetRealObject is called after this object is deserialized.
<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags:=SecurityPermissionFlag.SerializationFormatter)> _
Public Function GetRealObject(ByVal context As StreamingContext) As Object Implements IObjectReference.GetRealObject
' When deserialiing this object, return a reference to
' the Singleton object instead.
Return Singleton.GetSingleton()
End Function
End Class
Class App
<STAThread()> Shared Sub Main()
Dim fs As New FileStream("DataFile.dat", FileMode.Create)
Try
' Construct a BinaryFormatter and use it
' to serialize the data to the stream.
Dim formatter As New BinaryFormatter
' Create an array with multiple elements refering to
' the one Singleton object.
Dim a1() As Singleton = {Singleton.GetSingleton(), Singleton.GetSingleton()}
' This displays "True".
Console.WriteLine("Do both array elements refer to the same object? " & _
Object.ReferenceEquals(a1(0), a1(1)))
' Serialize the array elements.
formatter.Serialize(fs, a1)
' Deserialize the array elements.
fs.Position = 0
Dim a2() As Singleton = DirectCast(formatter.Deserialize(fs), Singleton())
' This displays "True".
Console.WriteLine("Do both array elements refer to the same object? " & _
Object.ReferenceEquals(a2(0), a2(1)))
' This displays "True".
Console.WriteLine("Do all array elements refer to the same object? " & _
Object.ReferenceEquals(a1(0), a2(0)))
Catch e As SerializationException
Console.WriteLine("Failed to serialize. Reason: " & e.Message)
Throw
Finally
fs.Close()
End Try
End Sub
End Class
Uwagi
Ta metoda jest przydatna w sytuacji komunikacji zdalnie, w której serializujesz obiekt proxy-creator, a nie rzeczywisty obiekt. Gdy obiekt proxy-creator jest deserializowany, deserializacja wywołuje jego GetRealObject metodę. W tym momencie obiekt proxy-creator tworzy nowe wystąpienie obiektu serwera proxy, które odwołuje się do oryginalnego rzeczywistego obiektu, być może na komputerze zdalnym. Na koniec obiekt proxy-creator zostanie odrzucony i odzyskany później przez odzyskiwanie pamięci.
Rozważmy Type na przykład sposób serializacji obiektów. Zamiast przesyłać dane z Type obiektu, system przesyła obiekt posiadacza o nazwie obiektu typu i informacje o zestawie, w którym znajduje się w obiekcie implementujący IObjectReferenceobiekt . Gdy dostępna jest zarówno nazwa typu, jak i nazwa zestawu, infrastruktura deserializacji wywołuje GetRealObject obiekt posiadacza, który został przesłany. Ten uchwyt zwraca Type obiekt wstawiony do grafu.