ASP.NET Tutorial/Page Lifecycle/GetCallbackEventReference

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Server side call back (C#)

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="RandomNumber" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Callback Page</title>
    
    <script type="text/javascript">
        function GetNumber(){     
            UseCallback();
        }
        
        function GetRandomNumberFromServer(TextBox1, context){   
            document.forms[0].TextBox1.value = TextBox1;
        }
    </script>
    
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <input id="Button1" 
               type="button" 
               value="Get Random Number" 
               onclick="GetNumber()" />
        <br />
        <br />
        <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
    </div>
    </form>
</body>
</html>
File: Default.aspx.cs
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class RandomNumber : System.Web.UI.Page, System.Web.UI.ICallbackEventHandler
{
    private string _callbackResult = null;
    protected void Page_Load(object sender, EventArgs e)
    {
        string cbReference = Page.ClientScript.GetCallbackEventReference(this, 
           "arg", "GetRandomNumberFromServer", "context");
        string cbScript = "function UseCallback(arg, context)" +
           "{" + cbReference + ";" + "}";
        Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
           "UseCallback", cbScript, true);
    }
    public void RaiseCallbackEvent(string eventArg)
    {
        Random rnd = new Random();
        _callbackResult = rnd.Next().ToString();
    }
    public string GetCallbackResult()
    {
        return _callbackResult;
    }
}


Server side call back (VB)

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="RandomNumber" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Callback Page</title>
    
    <script type="text/javascript">
        function GetNumber(){     
            UseCallback();
        }
        
        function GetRandomNumberFromServer(TextBox1, context){   
            document.forms[0].TextBox1.value = TextBox1;
        }
    </script>
    
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <input id="Button1" 
               type="button" 
               value="Get Random Number" 
               onclick="GetNumber()" />
        <br />
        <br />
        <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
    </div>
    </form>
</body>
</html>
File: Default.aspx.vb

Partial Class RandomNumber
    Inherits System.Web.UI.Page
    Implements System.Web.UI.ICallbackEventHandler
    Dim _callbackResult As String = Nothing
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
       Handles Me.Load
        Dim cbReference As String = Page.ClientScript.GetCallbackEventReference(Me, "arg", "GetRandomNumberFromServer", "context")
        Dim cbScript As String = "function UseCallback(arg, context)" & _
           "{" & cbReference & ";" & "}"
        Page.ClientScript.RegisterClientScriptBlock(Me.GetType(), _
           "UseCallback", cbScript, True)
    End Sub
    Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
        _callbackResult = Rnd().ToString()
    End Sub
    Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult
        Return _callbackResult
    End Function
End Class
Источник — «http://nfex.ru/index.php?title=ASP.NET_Tutorial/Page_Lifecycle/GetCallbackEventReference&oldid=3185»