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Page.RegisterAsyncTask(PageAsyncTask) Metoda

  • Reference

Definice

Obor názvů:
System.Web.UI
Sestavení:
System.Web.dll

Zaregistruje novou asynchronní úlohu na stránce.

public:
 void RegisterAsyncTask(System::Web::UI::PageAsyncTask ^ task);
public void RegisterAsyncTask (System.Web.UI.PageAsyncTask task);
member this.RegisterAsyncTask : System.Web.UI.PageAsyncTask -> unit
Public Sub RegisterAsyncTask (task As PageAsyncTask)

Parametry

task
PageAsyncTask

A PageAsyncTask , která definuje asynchronní úlohu.

Výjimky

ArgumentNullException

Asynchronní úkol je null.

Příklady

Následující příklad kódu ukazuje použití AsyncTimeout vlastnosti s ExecuteRegisteredAsyncTasks a RegisterAsyncTask metodami. Všimněte si použití obslužných rutin začátku, konce a časového limitu. V příkladu se zavádí umělá prodleva, která demonstruje situaci asynchronní úlohy překračující přidělený čas úkolu, jak je uvedeno ve AsyncTimeout vlastnosti. V reálném scénáři lze asynchronní úlohu použít k provádění volání databáze nebo generování image, například a obslužná rutina časového limitu poskytuje řádné snížení výkonu v případě, že úloha není provedena v zadaném časovém intervalu.

<%@ Page Language="C#" AsyncTimeout="2"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  protected void Page_Load(object sender, EventArgs e)
  {
    // Define the asynchronuous task.
    Samples.AspNet.CS.Controls.MyAsyncTask mytask =    
      new Samples.AspNet.CS.Controls.MyAsyncTask();
    PageAsyncTask asynctask = new PageAsyncTask(mytask.OnBegin, mytask.OnEnd, mytask.OnTimeout, null);

    // Register the asynchronous task.
    Page.RegisterAsyncTask(asynctask);
      
    // Execute the register asynchronous task.
    Page.ExecuteRegisteredAsyncTasks();

    TaskMessage.InnerHtml = mytask.GetAsyncTaskProgress();

  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Asynchronous Task Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <span id="TaskMessage" runat="server">
      </span>
    </div>
    </form>
</body>
</html>

<%@ Page Language="VB" AsyncTimeout="2"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
    
    ' Define the asynchronuous task.
    Dim mytask As New Samples.AspNet.VB.Controls.MyAsyncTask()
    Dim asynctask As New PageAsyncTask(AddressOf mytask.OnBegin, AddressOf mytask.OnEnd, AddressOf mytask.OnTimeout, DBNull.Value)

    ' Register the asynchronous task.
    Page.RegisterAsyncTask(asynctask)
      
    ' Execute the register asynchronous task.
    Page.ExecuteRegisteredAsyncTasks()

    TaskMessage.InnerHtml = mytask.GetAsyncTaskProgress()
    
  End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Asynchronous Task Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <span id="TaskMessage" runat="server">
      </span>
    </div>
    </form>
</body>
</html>

using System;
using System.Web;
using System.Web.UI;
using System.Threading;

namespace Samples.AspNet.CS.Controls
{
    public class MyAsyncTask
    {
        private String _taskprogress;
        private AsyncTaskDelegate _dlgt;

        // Create delegate.
        protected delegate void AsyncTaskDelegate();

        public String GetAsyncTaskProgress()
        {
            return _taskprogress;
        }
        public void DoTheAsyncTask()
        {
            // Introduce an artificial delay to simulate a delayed 
            // asynchronous task. Make this greater than the 
            // AsyncTimeout property.
            Thread.Sleep(TimeSpan.FromSeconds(5.0));
        }

        // Define the method that will get called to
        // start the asynchronous task.
        public IAsyncResult OnBegin(object sender, EventArgs e,
            AsyncCallback cb, object extraData)
        {
            _taskprogress = "Beginning async task.";

            _dlgt = new AsyncTaskDelegate(DoTheAsyncTask);
            IAsyncResult result = _dlgt.BeginInvoke(cb, extraData);

                        return result;
        }

        // Define the method that will get called when
        // the asynchronous task is ended.
        public void OnEnd(IAsyncResult ar)
        {
            _taskprogress = "Asynchronous task completed.";
            _dlgt.EndInvoke(ar);
        }

        // Define the method that will get called if the task
        // is not completed within the asynchronous timeout interval.
        public void OnTimeout(IAsyncResult ar)
        {
            _taskprogress = "Ansynchronous task failed to complete " +
                "because it exceeded the AsyncTimeout parameter.";
        }
    }
}

Imports System.Web
Imports System.Web.UI
Imports System.Threading

Namespace Samples.AspNet.VB.Controls

    Public Class MyAsyncTask

        Private _taskprogress As String
        Private _dlgt As AsyncTaskDelegate

        ' Create delegate.
        Delegate Function AsyncTaskDelegate()

        Public Function GetAsyncTaskProgress() As String
            Return _taskprogress
        End Function

        Public Function DoTheAsyncTask()

            ' Introduce an artificial delay to simulate a delayed 
            ' asynchronous task. Make this greater than the 
            ' AsyncTimeout property.
            Thread.Sleep(TimeSpan.FromSeconds(5.0))

        End Function


        ' Define the method that will get called to
        ' start the asynchronous task.
        Public Function OnBegin(ByVal sender As Object, ByVal e As EventArgs, ByVal cb As AsyncCallback, ByVal extraData As Object) As IAsyncResult

            _taskprogress = "Beginning async task."

            Dim _dlgt As New AsyncTaskDelegate(AddressOf DoTheAsyncTask)
            Dim result As IAsyncResult = _dlgt.BeginInvoke(cb, extraData)
            Return result

        End Function 'OnBegin

        ' Define the method that will get called when
        ' the asynchronous task is ended.
        Public Sub OnEnd(ByVal ar As IAsyncResult)

            _taskprogress = "Asynchronous task completed."
            _dlgt.EndInvoke(ar)

        End Sub

        ' Define the method that will get called if the task
        ' is not completed within the asynchronous timeout interval.
        Public Sub OnTimeout(ByVal ar As IAsyncResult)

            _taskprogress = "Ansynchronous task failed to complete because " & _
            "it exceeded the AsyncTimeout parameter."

        End Sub

    End Class

End Namespace

Poznámky

Definujte asynchronní úlohu pomocí PageAsyncTask třídy. Pokud je úkol definován, použijte metodu RegisterAsyncTask k registraci úkolu na stránce. Po registraci úlohy vyvoláte metodu ExecuteRegisteredAsyncTasks pro zahájení asynchronního úkolu.

Metodu RegisterAsyncTask lze použít s synchronními i asynchronními stránkami.

Platí pro

Viz také