IStateFormatter Interface

Definição

Define métodos que um tipo implementa para serializar e desserializar um gráfico de objeto.Defines methods that a type implements to serialize and deserialize an object graph.

public interface class IStateFormatter
public interface IStateFormatter
type IStateFormatter = interface
Public Interface IStateFormatter
Derivado

Exemplos

O exemplo de código a seguir demonstra como criar um PageStatePersister objeto que salva a exibição e o estado de controle em um fluxo no servidor Web.The following code example demonstrates how to create a PageStatePersister object that saves view and control state to a stream on the Web server. A StreamPageStatePersister classe demonstra como substituir os Load métodos e Save para extrair e salvar informações de estado da página.The StreamPageStatePersister class demonstrates how to override the Load and Save methods to extract and save page state information. Esses métodos usam a IStateFormatter interface herdada da PageStatePersister classe para serializar e desserializar o estado de exibição.These methods use the IStateFormatter interface inherited from the PageStatePersister class to serialize and deserialize view state. Este exemplo de código faz parte de um exemplo maior fornecido para a PageStatePersister classe.This code example is part of a larger example provided for the PageStatePersister class.

namespace Samples.AspNet.CS
{

    using System;
    using System.IO;
    using System.Security.Permissions;
    using System.Web;
    using System.Web.UI;

    //
    // The StreamPageStatePersister is an example view state
    // persistence mechanism that persists view and control
    // state on the Web server.
    //
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public class StreamPageStatePersister : PageStatePersister
    {

        public StreamPageStatePersister(Page page)
            : base(page)
        {
        }
        //
        // Load ViewState and ControlState.
        //
        public override void Load()
        {
            Stream stateStream = GetSecureStream();

            // Read the state string, using the StateFormatter.
            StreamReader reader = new StreamReader(stateStream);

            IStateFormatter formatter = this.StateFormatter;
            string fileContents = reader.ReadToEnd();

            // Deserilize returns the Pair object that is serialized in
            // the Save method.
            Pair statePair = (Pair)formatter.Deserialize(fileContents);

            ViewState = statePair.First;
            ControlState = statePair.Second;
            reader.Close();
            stateStream.Close();
        }
        //
        // Persist any ViewState and ControlState.
        //
        public override void Save()
        {

            if (ViewState != null || ControlState != null)
            {
                if (Page.Session != null)
                {
                    Stream stateStream = GetSecureStream();

                    StreamWriter writer = new StreamWriter(stateStream);

                    IStateFormatter formatter = this.StateFormatter;
                    Pair statePair = new Pair(ViewState, ControlState);

                    // Serialize the statePair object to a string.
                    string serializedState = formatter.Serialize(statePair);

                    writer.Write(serializedState);
                    writer.Close();
                    stateStream.Close();
                }
                else
                {
                    throw new InvalidOperationException("Session needed for StreamPageStatePersister.");
                }
            }
        }
        // Return a secure Stream for your environment.
        private Stream GetSecureStream()
        {
            // You must provide the implementation to build
            // a secure Stream for your environment.
            return null;
        }
    }
}
Imports System.IO
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.UI

Namespace Samples.AspNet.VB

    ' The StreamPageStatePersister is an example view state
    ' persistence mechanism that persists view and control
    ' state on the Web server.
    '
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public Class StreamPageStatePersister
        Inherits PageStatePersister


        Public Sub New(ByVal page As Page)
            MyBase.New(page)
        End Sub

        '
        ' Load ViewState and ControlState.
        '
        Public Overrides Sub Load()

            Dim stateStream As Stream
            stateStream = GetSecureStream()

            ' Read the state string, using the StateFormatter.
            Dim reader As New StreamReader(stateStream)

            Dim serializedStatePair As String
            serializedStatePair = reader.ReadToEnd
            Dim statePair As Pair

            Dim formatter As IStateFormatter
            formatter = Me.StateFormatter

            ' Deserilize returns the Pair object that is serialized in
            ' the Save method.      
            statePair = CType(formatter.Deserialize(serializedStatePair), Pair)

            ViewState = statePair.First
            ControlState = statePair.Second
            reader.Close()
            stateStream.Close()
        End Sub

        '
        ' Persist any ViewState and ControlState.
        '
        Public Overrides Sub Save()

            If Not (ViewState Is Nothing) OrElse Not (ControlState Is Nothing) Then
                If Not (Page.Session Is Nothing) Then

                    Dim stateStream As Stream
                    stateStream = GetSecureStream()

                    ' Write a state string, using the StateFormatter.
                    Dim writer As New StreamWriter(stateStream)

                    Dim formatter As IStateFormatter
                    formatter = Me.StateFormatter

                    Dim statePair As New Pair(ViewState, ControlState)

                    Dim serializedState As String
                    serializedState = formatter.Serialize(statePair)

                    writer.Write(serializedState)
                    writer.Close()
                    stateStream.Close()
                Else
                    Throw New InvalidOperationException("Session needed for StreamPageStatePersister.")
                End If
            End If
        End Sub
        ' Return a secure Stream for your environment.
        Private Function GetSecureStream() As Stream
            ' You must provide the implementation to build
            ' a secure Stream for your environment.
            Return Nothing
        End Function
    End Class
End Namespace

Comentários

A IStateFormatter interface define métodos que um tipo pode implementar para serializar e desserializar o estado que um controle de servidor Web ASP.NET mantém em sua ViewState propriedade.The IStateFormatter interface defines methods that a type can implement to serialize and deserialize the state that an ASP.NET Web server control maintains in its ViewState property. Essa infraestrutura é usada por classes que derivam da PageStatePersister classe para manter o estado de uma página de ASP.net entre as solicitações.This infrastructure is used by classes that derive from the PageStatePersister class to maintain an ASP.NET page's state between requests. Por padrão, o estado da página ASP.NET é serializado e desserializado por uma instância da ObjectStateFormatter classe; no entanto, os desenvolvedores de site e adaptador podem implementar a IStateFormatter interface em seus próprios tipos para executar esse trabalho.By default, ASP.NET page state is serialized and deserialized by an instance of the ObjectStateFormatter class; however, site and adapter developers can implement the IStateFormatter interface on their own types to perform this work.

Para obter mais informações sobre o gerenciamento de estado de controle de servidor Web e o estado de exibição, consulte visão geral do gerenciamento de estado ASP.net e controles de servidor Web dinâmicos e estado de exibição.For more information about Web server control state management and view state, see ASP.NET State Management Overview and Dynamic Web Server Controls and View State.

Métodos

Deserialize(String)

Desserializa um gráfico de estado do objeto da sua forma de cadeia de caracteres serializada.Deserializes an object state graph from its serialized string form.

Serialize(Object)

Serializa o estado de controle de servidor Web do ASP.NET para o formulário de cadeia de caracteres.Serializes ASP.NET Web server control state to string form.

Aplica-se a

Confira também