将文件下载在UpdatePanel中，并带有Out Backbacktrigger

Question

我正在使用代码的这一部分来下载文件，使用onClick for ImageButton for Insim updatePanel ，如果我添加imageButton为 postbackbacktrigger，它可以正常工作。对于UpdatePanel，是否可以做到，没有完整的powback？

        Dim stream As IO.Stream = Nothing
        Dim bytesToRead As Integer = 10000
        Dim buffer As Byte() = New Byte(bytesToRead - 1) {}
        Try
            Dim fileReq As Net.HttpWebRequest = CType(Net.HttpWebRequest.Create(FileURL), Net.HttpWebRequest)
            Dim fileResp As Net.HttpWebResponse = CType(fileReq.GetResponse(), Net.HttpWebResponse)
            If fileReq.ContentLength > 0 Then fileResp.ContentLength = fileReq.ContentLength
            stream = fileResp.GetResponseStream()
            Dim resp = HttpContext.Current.Response
            resp.ContentType = "application/octet-stream"
            resp.AddHeader("Content-Disposition", "attachment; filename=""" & FileName & """")
            resp.AddHeader("Content-Length", fileResp.ContentLength.ToString())
            Dim length As Integer
            Do
                If resp.IsClientConnected Then
                    length = stream.Read(buffer, 0, bytesToRead)
                    resp.OutputStream.Write(buffer, 0, length)
                    resp.Flush()
                    buffer = New Byte(bytesToRead - 1) {}
                Else
                    length = -1
                End If
            Loop While length > 0
        Finally
            If stream IsNot Nothing Then
                stream.Close()
            End If
        End Try

Answer 1

我找到了解决方案。@Hatcha在 asp：从ASHX文件下载文件时，进度不会结束厌食。@vdwwd所说的很棒，但在我的情况下不是，因为我需要一个按钮创建pdf file ，然后开始下载。这意味着客户端点击将不会有用。

ScriptManager.RegisterClientScriptBlock(Me, GetType(Page), "downloadFileExport", "javascript:window.location ='" & ResolveUrl("~/report/download.ashx?url=" & url & "&fName=" & fName) & "';", True)