在清除响应之前，我如何输出到webform

我有一个Webform，用户单击一个按钮，生成一个Excel文件。这是通过以下代码实现的:

Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=export.txt");
Response.ContentType = "text/csv";
Response.WriteFile(FILENAME);
Response.End();

我想添加到响应，以便当用户关闭Excel时，他们可以在Webform上看到消息。但是你不能在上面的代码中这样做。

Response.Write("Excel generated!"); ************ does not work as response will be cleared!
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=donman_export.txt");
Response.ContentType = "text/csv";
Response.WriteFile(FILENAME);
Response.End();

我该怎么做?

Response.Write("Excel generated!"); ************ does not work
Response.Flush();
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=donman_export.txt");
Response.ContentType = "text/csv";
Response.WriteFile(FILENAME);
Response.End();

下面的代码正是你所要求的。

它呈现额外的HTML标签，所以在消息显示给用户后开始下载:

    protected void Page_Load(object sender, EventArgs e)
    {
        var currentUrl   = Request.Url.OriginalString;
        var currentQuery = Request.Url.Query;
        var download = new
        {
            FilePath   = "~/test.csv",
            FileName   = "test.csv",
            FileMime   = "text/csv",
            Message    = "Excel generated!",         
            QueryParam = "direct-download",
            Delay      = 2 // seconds
        };
        var hasQueryParams = currentQuery.Length > 0;
        var isDownloadUrl  = hasQueryParams && currentQuery.IndexOf( download.QueryParam ) >= 0;
        if( isDownloadUrl ) 
        {  
            // Prepare..
            Response.ContentType = download.FileMime;
            Response.Clear();
            Response.BufferOutput = true;
            // Transfer..
            Response.AddHeader("content-disposition", "attachment; filename=" + download.FileName);
            Response.WriteFile(download.FilePath);
            // Done..
            // Instead of Response.Close()
            // http://stackoverflow.com/q/4583201/2361743
            Response.Flush();
            Context.ApplicationInstance.CompleteRequest(); 
            return;
        }
        // Meta-Refresh Tag has to be in <HEAD> section, but not all browsers follow this restriction.
        // IFRAME has to work fine. It is wrapped into <DIV> to be not visible in old browsers.
        const string tagToStartManual      = "<A href='{0}'>{1}</A>"; 
        const string tagToStartAfterDelay  = "<META HTTP-EQUIV='REFRESH' CONTENT='{1};URL={0}'>";
        const string tagToStartImmediately = "<DIV STYLE='{1}'><IFRAME SRC='{0}'></IFRAME></DIV>";
        const string cssToHideFrame        = "width:1px;height:1px;opacity:0.1;overflow:hidden";
        // Show your message..
        // And add HTML Tags which would start download:
        Response.Write(download.Message);
        var downloadUrl = currentUrl + (hasQueryParams ? "&" : "?") + download.QueryParam;
        // You don't have to use all 3 methods...
        Response.Write( String.Format( tagToStartManual, downloadUrl, download.FileName));
        Response.Write( String.Format( tagToStartAfterDelay, downloadUrl, download.Delay) ); 
        Response.Write( String.Format( tagToStartImmediately, downloadUrl, cssToHideFrame) );
        // Done. 
        // Waiting for actual download request...
    }

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