SerializationInfo.SetType Method (Type)
.NET Framework (current version)
Sets the Type of the object to serialize.
Assembly: mscorlib (in mscorlib.dll)
| Exception | Condition |
|---|---|
| ArgumentNullException | The type parameter is null. |
The Formatter is responsible for setting the Type of the SerializationInfo instance before passing it to GetObjectData. However, users who want to send proxies for their objects will need to change the type represented by this SerializationInfo instance. Using the SetType method is equivalent to setting both the FullTypeName and the AssemblyName.
Imports System 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
.NET Framework
Available since 1.1
Available since 1.1
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