AsyncCallback函数不起作用

Question

我有一个文件夹，里面有很多PDF文件。当用户从DropDownList中选择类别并单击按钮时，系统会将文件(不是全部)复制到一个新文件夹中，然后生成压缩文件。

这些步骤都没问题，但问题是生成的zip服务什么时候结束。

我要写一个例子：

<asp:Content ID="Content2" ContentPlaceHolderID="body" runat="Server">

    <asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server">
        <Services>
            <asp:ServiceReference Path="SomeService.asmx" InlineScript="true" />
        </Services>
    </asp:ScriptManagerProxy>

    <script type="text/javascript">
        function copyFiles(id) {
            SomeService.CopyFiles($ja("#DropDownList1").val(), id, FuncionSucceeded, FuncionFailed);
        }

        function FuncionSucceeded(result, eventArgs) {
            document.getElementById("GenerateZip").click();
        }

        function FuncionFailed(result, eventArgs) {

        }


    </script>

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            <asp:Button ID="Button1" runat="server" Text="Generate Zip" />
            <asp:Timer ID="Timer1" runat="server" Interval="5000" Enabled="false">
            </asp:Timer>
            <asp:Button ID="btnGenerateZip" runat="server" Style="display: none;" ClientIDMode="Static" />
            <asp:Image ID="Image1" runat="server" ImageUrl="~/images/loading.gif"
                Visible="False" />
            <asp:Label ID="Label1" runat="server" Text="" Visible="false"></asp:Label>
            <asp:LinkButton runat="server" Visible="false" ID="linkzip" Text="Descargar" />
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
        </Triggers>
    </asp:UpdatePanel>
</asp:Content>

和代码：

'This code call the client side to copy the files
Protected Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click
    If DropDownList1.SelectedValue = "0" Then
         Exit Sub
    End If

     Dim pathName As String = "The path here"

    If Not File.Exists(pathName) Then
        Dim folder As String = Path.GetDirectoryName(pathName)
        If Not Directory.Exists(folder) Then
            Directory.CreateDirectory(folder)
        End If
    End If

    Image1.Visible = True
    Label1.Visible = True
    Timer1.Enabled = True
    Label1.Text = "Generating zip"

    Dim script As String = "copyFiles('1234');"
    ScriptManager.RegisterClientScriptBlock(Me.Page, Me.Page.GetType(), Guid.NewGuid().ToString(), script, True)

End Sub

'When the client side returns the function `FunctionSucceeded` call next function

Private Sub btnGenerateZip_Click(sender As Object, e As EventArgs) Handles btnGenerarZip.Click
    GenerateZip()
End Sub

Private Sub GenerateZip()
    Try
        Dim ws As New AnotherService.ServiceExample
        Dim ar2 As New AsyncCallback(AddressOf DownloadFile)
        Dim pathName As String = String.Format("{0}", path)

        result = ws.BeginSomeFunction(path, ar2, ws)

     Catch ex As Exception
        generaZip = False
    End Try

End Sub

和回调函数：

Protected Sub DownloadFile(ar As IAsyncResult)
        Dim ws As New AnotherService.ServiceExample
        Try
            Dim pathName As String ="Path"
            ws.deleteFolder(pathName)
            ws.EndSomeFunction(ar)
            Image1.Visible = False
            Label1.Text = "OK"
            Timer1.Enabled = Image1.Visible
            linkzip.Visible = True
            generaZip = True
        Catch ex As Exception
            generaZip = False
        End Try
    End Sub

和定时器滴答：

Protected Sub Timer1_Tick(sender As Object, e As System.EventArgs) Handles Timer1.Tick
        Select Case generaZip
            Case True
                Image1.Visible = False
                Label1.Text = "Everything is ok"
                Timer1.Enabled = Image1.Visible
                linkzip.Visible = True
            Case False
                Image1.Visible = False
                Label1.Text = "Error"
                Timer1.Enabled = Image1.Visible
        End Select

    End Sub

问题是，当我们在DownloadFile函数(异步回调函数)中时，我在那里所做的任何事情都不起作用。我更改了许多属性、值、变量值，当tick函数触发时，就像我什么也没做一样。

我已经更改了所有这些行：

Image1.Visible = False
Label1.Text = "OK."
Timer1.Enabled = Image1.Visible
linkzip.Visible = True
generaZip = True