如何在回发发生时启动加载程序，然后加载程序应在 ASP.NET 后停止？

Question

当用户单击“导出”按钮时，我触发加载程序事件以启动加载程序。使用 jquery 在客户端完成了哪种方法。回发发生在我将使用 itextsharp 从 HTML 字符串生成大量 PDF 文档的地方。毕竟，生成了所有这些压缩文件并在客户端浏览器中下载。

我执行以下操作：

 Response.AddHeader("Content-Disposition", "attachment; filename=output.zip");
    Response.TransmitFile(zipPath);

因为下载后无法停止该加载程序。

服务器端代码在后面：

protected void Button1_Click(object sender, EventArgs e)
{
    string test = GetImportDetailsPDF("ImportFile(2)_2017.12.19-12.30.24.xlsx");
    //Generated all pdf files zipped and downloaded here
    string startPath = Server.MapPath("/ImportPdf/");
    string zipPath = Server.MapPath("/ImportZip/result.zip");

    ZipFile.CreateFromDirectory(startPath, zipPath);

    System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
    response.ClearContent();
    response.Clear();
    Response.ContentType = "image/jpeg";
    Response.AddHeader("Content-Disposition", "attachment; filename=output.zip");
    Response.TransmitFile(zipPath);

    HttpContext.Current.Response.Flush(); // Sends all currently buffered output to the client.
    HttpContext.Current.Response.SuppressContent = true;  // Gets or sets a value indicating whether to send HTTP content to the client.
    HttpContext.Current.ApplicationInstance.CompleteRequest(); // Causes ASP.NET to bypass all events and filtering in the HTTP pipeline chain of execution and directly execute the EndRequest event.
    HttpContext.Current.Response.End();
}

public string GetImportDetailsPDF(string FileName)
{

    return "Successfully Imported";
}

Answer 1

尝试以下客户端解决方案 基于Sys.WebForms.PageRequestManager class:

<!-- language: html -->
    <script type="text/javascript">
        var prm = Sys.WebForms.PageRequestManager.getInstance();
        prm.add_initializeRequest(prm_InitializeRequest);
        prm.add_endRequest(prm_EndRequest);
        function prm_InitializeRequest(sender, args) {
            //show screen blocker
        }
        function prm_EndRequest(sender, args) {
            //hide screen blocker after a file is generated
            //DoClick to download a prepared file
        }
    </script>

使用 UpdatePanel，您可以获得一个非常流畅的解决方案：在文件下载开始之前，您的最终用户将看不到任何回发属性。

您可以找到此方法的详细说明并查看此解决方案的实际应用 here。

如何在回发发生时启动加载程序，然后加载程序应在 ASP.NET 后停止？

How to start a loader when a postback happens,then after that loader should be stopped in ASP.NET?

asp.net-4.0

c#-4.0