Page.ExecuteRegisteredAsyncTasks Metode
Definisi
Penting
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Memulai eksekusi tugas asinkron.
public:
void ExecuteRegisteredAsyncTasks();public void ExecuteRegisteredAsyncTasks ();member this.ExecuteRegisteredAsyncTasks : unit -> unitPublic Sub ExecuteRegisteredAsyncTasks ()Pengecualian
Ada pengecualian dalam tugas asinkron.
Contoh
Contoh kode berikut menunjukkan penggunaan AsyncTimeout properti dengan ExecuteRegisteredAsyncTasks metode dan RegisterAsyncTask . Perhatikan penggunaan handler awal, akhir, dan waktu habis. Dalam contoh, penundaan buatan diperkenalkan untuk menunjukkan situasi tugas asinkron yang melebihi waktu yang dialokasikan untuk tugas seperti yang ditentukan dalam AsyncTimeout properti . Dalam skenario dunia nyata, tugas asinkron dapat digunakan untuk melakukan panggilan database atau pembuatan gambar, misalnya, dan handler waktu habis memberikan degradasi yang anggun jika tugas tidak dilakukan dalam jumlah waktu tertentu.
<%@ 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
Keterangan
Tentukan tugas asinkron menggunakan PageAsyncTask kelas . Setelah tugas ditentukan, dan terdaftar di halaman menggunakan RegisterAsyncTask metode , ExecuteRegisteredAsyncTasks metode dapat dipanggil untuk memulai tugas asinkron.
Metode ExecuteRegisteredAsyncTasks ini secara otomatis dipanggil pada titik dalam pemrosesan halaman ketika ada tugas asinkron terdaftar, jika ada, dipanggil untuk halaman non-asinkron. Panggilan otomatis ini ExecuteRegisteredAsyncTasks terjadi tepat sebelum PreRenderComplete peristiwa. ExecuteRegisteredAsyncTasks Panggil metode untuk tugas yang ingin Anda panggil kadang-kadang selain panggilan otomatis ke metode ini. Perhatikan, tugas asinkron hanya akan dijalankan sekali meskipun ExecuteRegisteredAsyncTasks dapat dipanggil lebih dari sekali.
Properti AsyncTimeout diatur ulang pada setiap panggilan ke ExecuteRegisteredAsyncTasks metode . Nilai terakhir sebelum AsyncTimeout memanggil ExecuteRegisteredAsyncTasks metode lebih diutamakan. Jika tugas asinkron membutuhkan lebih dari AsyncTimeout, tugas berikutnya yang dipanggil selama panggilan tersebut ExecuteRegisteredAsyncTasks segera habis.
