StreamingContext.Context-Eigenschaft

Ruft Kontext ab, der als Teil des zusätzlichen Kontexts angegeben ist.

Namespace: System.Runtime.Serialization
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public ReadOnly Property Context As Object
'Usage
Dim instance As StreamingContext
Dim value As Object

value = instance.Context

public Object Context { get; }

public:
property Object^ Context {
    Object^ get ();
}

/** @property */
public Object get_Context ()

public function get Context () : Object

Eigenschaftenwert

Der Kontext, der als Teil des zusätzlichen Kontexts angegeben ist.

Hinweise

Dieser kann NULL (Nothing in Visual Basic) sein.

Beispiel

Im folgenden Beispiel wird mithilfe des state-Parameters und des additional-Parameters eine Instanz der StreamingContext-Klasse erstellt. Im Code wird auch veranschaulicht, wie ein Objekt deserialisiert und der Wert der Context-Eigenschaft abgerufen wird.

Imports System
Imports System.Text
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Runtime.Serialization
Imports System.IO
Imports System.Security.Permissions


Class Program
    
    Shared Sub Main(ByVal args() As String) 
        Try
            SerializeAndDeserialize()
        Catch exc As System.Exception
            Console.WriteLine(exc.Message)
        Finally
            Console.WriteLine("Press <Enter> to exit....")
            Console.ReadLine()
        End Try
    
    End Sub 
    
    Shared Sub SerializeAndDeserialize() 
        Dim myObject As Object = DateTime.Now
        ' Create a StreamingContext that includes a
        ' a DateTime. 
        Dim sc As New StreamingContext(StreamingContextStates.CrossProcess, myObject)
        Dim bf As New BinaryFormatter(Nothing, sc)
        Dim ms As New MemoryStream(New Byte(2047) {})
        bf.Serialize(ms, New [MyClass]())
        ms.Seek(0, SeekOrigin.Begin)
        Dim f As [MyClass] = CType(bf.Deserialize(ms), [MyClass])
        Console.WriteLine(vbTab + " MinValue: {0} " + vbLf + vbTab + " MaxValue: {1}", f.MinValue, f.MaxValue)
        Console.WriteLine("StreamingContext.State: {0}", sc.State)
        
        Dim myDateTime As DateTime = CType(sc.Context, DateTime)
        Console.WriteLine("StreamingContext.Context: {0}", myDateTime.ToLongTimeString())
    
    End Sub 
End Class 

<Serializable(), SecurityPermission(SecurityAction.Demand, SerializationFormatter := True)>  _
Class [MyClass]
    Implements ISerializable
    Private minValue_value As Integer
    Private maxValue_value As Integer
    
    Public Sub New() 
        minValue_value = Integer.MinValue
        maxValue_value = Integer.MaxValue    
    End Sub     
    
    Public Property MinValue() As Integer 
        Get
            Return minValue_value
        End Get
        Set
            minValue_value = value
        End Set
    End Property 
    
    Public Property MaxValue() As Integer 
        Get
            Return maxValue_value
        End Get
        Set
            maxValue_value = value
        End Set
    End Property
     
    Sub GetObjectData(ByVal si As SerializationInfo, ByVal context As StreamingContext)  Implements ISerializable.GetObjectData
        si.AddValue("minValue", minValue_value)
        si.AddValue("maxValue", maxValue_value)
    
    End Sub   
    
    Protected Sub New(ByVal si As SerializationInfo, ByVal context As StreamingContext) 
        minValue_value = Fix(si.GetValue("minValue", GetType(Integer)))
        maxValue_value = Fix(si.GetValue("maxValue", GetType(Integer)))
    End Sub 
End Class 

using System;
using System.Text;
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;
using System.IO;
using System.Security.Permissions;

namespace StreamingContextExample
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                SerializeAndDeserialize();
            }
            catch (System.Exception exc)
            {
                Console.WriteLine(exc.Message);
            }
            finally
            {
                Console.WriteLine("Press <Enter> to exit....");
                Console.ReadLine();
            }
        }
        static void SerializeAndDeserialize()
        {
            object myObject = DateTime.Now;
            // Create a StreamingContext that includes a
            // a DateTime. 
            StreamingContext sc = new StreamingContext(
                StreamingContextStates.CrossProcess, myObject);
            BinaryFormatter bf = new BinaryFormatter(null, sc);
            MemoryStream ms = new MemoryStream(new byte[2048]);
            bf.Serialize(ms, new MyClass());
            ms.Seek(0, SeekOrigin.Begin);
            MyClass f = (MyClass)bf.Deserialize(ms);
            Console.WriteLine("\t MinValue: {0} \n\t MaxValue: {1}", 
                f.MinValue , f.MaxValue);
            Console.WriteLine("StreamingContext.State: {0}", 
                sc.State);

            DateTime myDateTime = (DateTime)sc.Context;
            Console.WriteLine("StreamingContext.Context: {0}",
                myDateTime.ToLongTimeString());
        }
    }

    [Serializable]
    [SecurityPermission(SecurityAction.Demand, SerializationFormatter = true)]
    class MyClass : ISerializable
    {
        private int minValue_value;
        private int maxValue_value;

        public MyClass()
        {
            minValue_value = int.MinValue;
            maxValue_value = int.MaxValue;
        }

        public int MinValue
        {
            get { return minValue_value; }
            set { minValue_value = value;}
        }

        public int MaxValue
        {
            get { return maxValue_value; }
            set { maxValue_value = value; }
        }

        void ISerializable.GetObjectData(SerializationInfo si, StreamingContext context)
        {
            si.AddValue("minValue", minValue_value);
            si.AddValue("maxValue", maxValue_value);
        }

        protected MyClass(SerializationInfo si, StreamingContext context)
        {
            minValue_value = (int)si.GetValue("minValue", typeof(int));
            maxValue_value = (int)si.GetValue("maxValue", typeof(int));            
        }
    }
}

Plattformen

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

StreamingContext-Struktur
StreamingContext-Member
System.Runtime.Serialization-Namespace
Equals