Page.EnableViewState-Eigenschaft

Ruft einen Wert ab, der angibt, ob die Seite ihren Ansichtszustand sowie den Ansichtszustand aller enthaltenen Serversteuerelemente beibehält, wenn die aktuelle Seitenanforderung beendet wird, oder legt diesen fest.

Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)

Syntax

'Declaration
Public Overrides Property EnableViewState As Boolean
'Usage
Dim instance As Page
Dim value As Boolean

value = instance.EnableViewState

instance.EnableViewState = value

public override bool EnableViewState { get; set; }

public:
virtual property bool EnableViewState {
    bool get () override;
    void set (bool value) override;
}

/** @property */
public boolean get_EnableViewState ()

/** @property */
public void set_EnableViewState (boolean value)

public override function get EnableViewState () : boolean

public override function set EnableViewState (value : boolean)

Eigenschaftenwert

true, wenn die Seite ihren Ansichtszustand beibehält, andernfalls false. Der Standardwert ist true.

Hinweise

Auch wenn EnableViewState den Wert false aufweist, wird möglicherweise ein ausgeblendetes Feld für den Ansichtszustand mit der Seite gerendert, das von ASP.NET zum Erkennen von Postback verwendet wird.

Beispiel

Im folgenden Codebeispiel wird die EnableViewState-Eigenschaft beim Laden der Seite auf false festgelegt. Dadurch wird der Ansichtszustand für das Page-Objekt deaktiviert, was bedeutet, dass weder Informationen über den Ansichtszustand der Seite noch über die Steuerelemente auf der Seite gespeichert werden.

Public Class WebPage
   Inherits System.Web.UI.Page
   Private myFormObj As MyForm
   Private label1 As Label
   Private label2 As Label
   Private textBoxObj As TextBox
   Private buttonObj As Button
   
   Public Sub New()
      AddHandler Page.Init, AddressOf Page_Init
   End Sub 'New
   
   
   Private Sub Page_Load(sender As Object, e As System.EventArgs)
      ' Comment the following line to maintain page view state.
      Page.EnableViewState = false
      myFormObj.Method = "post"
      Controls.Add(myFormObj)
      textBoxObj.Text = "Welcome to .NET"
      
      label1.Text = "Enter a name"
      buttonObj.Text = "ClickMe"
      AddHandler buttonObj.Click, AddressOf Button_Click
      myFormObj.Controls.Add(label1)
      myFormObj.Controls.Add(textBoxObj)
      myFormObj.Controls.Add(buttonObj)
      myFormObj.Controls.Add(label2)
   End Sub 'Page_Load
   
   Private Sub Button_Click(sender As Object, e As EventArgs)
      Dim temp As [String] = "<br>Name is " + textBoxObj.Text + "<br>"
      temp += "Saved content of previous page is " + CType(ViewState("name"), String)
      label2.Text = temp
   End Sub 'Button_Click
   
   Protected Overrides Sub LoadViewState(viewState As Object)
      If Not (viewState Is Nothing) Then
         MyBase.LoadViewState(viewState)
      End If
   End Sub 'LoadViewState
   
   Protected Overrides Function SaveViewState() As Object
      ViewState("name") = textBoxObj.Text
      Return MyBase.SaveViewState()
   End Function 'SaveViewState
   
   Private Sub Page_Init(sender As Object, e As EventArgs)
      AddHandler Me.Load, AddressOf Me.Page_Load
      myFormObj = New MyForm()
      label1 = New Label()
      label2 = New Label()
      textBoxObj = New TextBox()
      buttonObj = New Button()
   End Sub 'Page_Init
End Class 'WebPage

public class WebPage : Page
{
   private MyForm myFormObj;
   private Label label1;
   private Label label2;
   private TextBox textBoxObj;
   private Button buttonObj;

   public WebPage()
   {
      Page.Init += new System.EventHandler(Page_Init);
   }

   private void Page_Load(object sender, System.EventArgs e)
   {
      // Comment the following line to maintain page view state.
      Page.EnableViewState = false;
      myFormObj.Method = "post";
      Controls.Add(myFormObj);
      textBoxObj.Text = "Welcome to .NET";

      label1.Text = "Enter a name";
      buttonObj.Text = "ClickMe";
      buttonObj.Click += new EventHandler(Button_Click);
      myFormObj.Controls.Add(label1);
      myFormObj.Controls.Add(textBoxObj);
      myFormObj.Controls.Add(buttonObj);
      myFormObj.Controls.Add(label2);
   }
   private void Button_Click(object sender, EventArgs e)
   {
      String temp = "<br>Name is " + textBoxObj.Text + "<br>";
      temp += "Saved content of previous page is " + ViewState["name"] as String;
      label2.Text = temp;
   }
   protected override void LoadViewState(object viewState)
   {
      if(viewState != null)
         base.LoadViewState(viewState);
   }
   protected override object SaveViewState()
   {
      ViewState["name"] = textBoxObj.Text;
      return base.SaveViewState();
   }
   private void Page_Init(object sender, EventArgs e)
   {
      this.Load += new System.EventHandler(this.Page_Load);

      myFormObj = new MyForm();
      label1 = new Label();
      label2 = new Label();
      textBoxObj = new TextBox();
      buttonObj = new Button();
   }
};

public class WebPage extends Page
{
    private MyForm myFormObj;
    private Label label1;
    private Label label2;
    private TextBox textBoxObj;
    private Button buttonObj;

    public WebPage()
    {
        get_Page().add_Init(new System.EventHandler(Page_Init));
    } //WebPage

    private void Page_Load(Object sender, System.EventArgs e)
    {
        // Comment the following line to maintain page view state.
        get_Page().set_EnableViewState(false);
        myFormObj.set_Method("post");
        get_Controls().Add(myFormObj);
        textBoxObj.set_Text("Welcome to .NET");
        label1.set_Text("Enter a name");
        buttonObj.set_Text("ClickMe");
        buttonObj.add_Click(new EventHandler(Button_Click));
        myFormObj.get_Controls().Add(label1);
        myFormObj.get_Controls().Add(textBoxObj);
        myFormObj.get_Controls().Add(buttonObj);
        myFormObj.get_Controls().Add(label2);
    } //Page_Load

    private void Button_Click(Object sender, EventArgs e)
    {
        String temp = "<br>Name is " + textBoxObj.get_Text() + "<br>";
        temp += "Saved content of previous page is " 
            + get_ViewState().get_Item("name");
        label2.set_Text(temp);
    } //Button_Click

    protected void LoadViewState(Object viewState)
    {
        if (viewState != null) {
            super.LoadViewState(viewState);
        }
    } //LoadViewState

    protected Object SaveViewState()
    {
        get_ViewState().set_Item("name", textBoxObj.get_Text());
        return super.SaveViewState();
    } //SaveViewState

    private void Page_Init(Object sender, EventArgs e)
    {
        this.add_Load(new System.EventHandler(this.Page_Load));
        myFormObj = new MyForm();
        label1 = new Label();
        label2 = new Label();
        textBoxObj = new TextBox();
        buttonObj = new Button();
    } //Page_Init
} //WebPage

Plattformen

Windows 98, Windows 2000 SP4, 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

Page-Klasse
Page-Member
System.Web.UI-Namespace
EnableViewStateMac