从调用静态方法Response.TransmitFile（） [英] Calling Response.TransmitFile() from static method

问题描述

我有许多这就需要导出数据支持到Excel US preadsheet页面。我可以生成Excel文件就好了，但我试图找出如何抽象这种行为所以它的所有的地方，我需要它的网页很容易重用。我现在的想法是使用一个静态的实用方法，如下所示：

I have a number of pages which need to support exporting data to an Excel spreadsheet. I can generate the Excel files just fine, but I'm trying to work out how to abstract this behavior so it's easily reusable from all of the pages where I need it. My current idea is to use a static utility method, as follows:

public static void SendExcelFile(System.Web.UI.Page callingPage, string downloadFileName, List<List<string>> data, string worksheetTitle)
{
    string tempFileName = Path.GetTempFileName();

    try
    {
        // Generate file using ExcelPackage
        GenerateExcelDoc(tempFileName, data, worksheetTitle);

        callingPage.Response.AddHeader("Content-Disposition", "attachment;filename=" + downloadFileName);
        callingPage.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        callingPage.Response.AddHeader("Content-Length", new FileInfo(tempFileName).Length.ToString());
        callingPage.Response.TransmitFile(tempFileName);
    }
    finally
    {
        //When this is removed, the method works as expected.
        if (File.Exists(tempFileName))
            File.Delete(tempFileName);  
    }
}

在这里我打电话单击处理 SendExcelFile 是这样的：

protected void lnkExport_Click(object sender, EventArgs e)
{
    List<List<string>> dataList = GatherDataForSpreadsheet();
    Utility.SendExcelFile(this, "fileNameForDownload.xlsx", dataList, "MyReports");
}

这code的作品就好作为调用页面的一个实例方法。作为一个静态方法，但是，它根本不工作。当我点击调用这个按钮，浏览器显示加载动画无限期的，但从来没有提示输入文件下载。

This code works just fine as an instance method of the calling page. As a static method, though, it doesn't work at all. When I click the button that invokes this, the browser shows the loading animations indefinitely, but never prompts for a file download.

我很新的ASP.NET（和一般的web编程），所以我敢肯定，我在这里失去了一些东西。可能有人请解释一下我看到的行为，并提出一个合理的选择这种方法？

I'm very new to ASP.NET (and web programming in general), so I'm sure I'm missing something here. Could someone please explain the behavior I'm seeing, and suggest a reasonable alternative to this approach?

编辑：如果我删除调用File.Delete（）末，该方法按预期工作。是否Response.TransmitFile（）做传输异步？

If I remove the call to File.Delete() at the end, the method works as expected. Does Response.TransmitFile() do the transfer asynchronously?

编辑2：我只需要调用Response.Flush（）之前，我删除的文件。见我的回答如下。
谢谢！

EDIT 2: I just needed to call Response.Flush() before I deleted the file. See my answer below. Thanks!

推荐答案

的问题是，在数据被向下发送的临时文件被删除。我只需要调用Response.Flush（）像这样：

The problem was that the temp file was being deleted before the data was sent down. I just needed to call Response.Flush() like so:

public static void SendExcelFile(System.Web.UI.Page callingPage, string downloadFileName, List<List<string>> data, string worksheetTitle)
{
    string tempFileName = Path.GetTempFileName();

    try
    {
        // Generate file using ExcelPackage
        GenerateExcelDoc(tempFileName, data, worksheetTitle);

        callingPage.Response.AddHeader("Content-Disposition", "attachment;filename=" + downloadFileName);
        callingPage.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        callingPage.Response.AddHeader("Content-Length", new FileInfo(tempFileName).Length.ToString());
        callingPage.Response.TransmitFile(tempFileName);
        callingPage.Response.Flush();  //This is what I needed
    }
    finally
    {
        if (File.Exists(tempFileName))
            File.Delete(tempFileName);  
    }
}

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