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从静态方法调用Response.TransmitFile()

response asp.net c#

3

Odrade · 技术社区 · 16 年前

我有许多页面需要支持将数据导出到Excel电子表格。我可以很好地生成Excel文件,但我正在尝试解决如何抽象这种行为,以便可以轻松地从我需要的所有页面重用它。我目前的想法是使用静态实用方法,如下所示:

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);  
    }
}

我呼叫的点击处理程序 SendExcelFile 看起来像这样:

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

这段代码作为调用页面的实例方法工作得很好。但是,作为一种静态方法,它根本不起作用。当我单击调用此功能的按钮时,浏览器会无限期地显示正在加载的动画,但不会提示下载文件。

我对ASP.NET(以及一般的web编程)非常陌生,所以我确信我在这里遗漏了一些东西。有人能解释一下我看到的行为,并提出一个合理的替代方法吗?

编辑:如果在最后删除对File.Delete()的调用,则该方法将按预期工作。Response.TransmitFile()是否异步进行传输?

编辑2:我只需要在删除文件之前调用Response.Flush()。见下面我的答案。谢谢

5 回复 | 直到 16 年前

1

5

Odrade 13 年前

问题是临时文件在发送数据之前被删除。我只需要调用Response.Flush(),如下所示:

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);  
    }
}

2

1

Nick Craver 16 年前

试试这个,你可以得到 Request 和 Response 马上 HttpContext.Current :

public static void SendExcelFile(string downloadFileName, List<List<string>> data, string worksheetTitle)
{
    var context = HttpContext.Current;
    string tempFolder = context.Request.PhysicalApplicationPath + "temp";
    string tempFileName = tempFolder + "tempFileName.xlsx"

    if (!Directory.Exists(tempFolder))
        Directory.CreateDirectory(tempFolder);

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

    context.Response.AddHeader("Content-Disposition", "attachment;filename=" + downloadFileName);
    context.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
    context.Response.AddHeader("Content-Length", new FileInfo(tempFileName).Length.ToString());
    context.Response.TransmitFile(tempFileName);

    File.Delete(tempFileName);
}

另一种选择是为包含此方法的页面创建基类,这可能是一种更简单的路由。您的页面不必从System.Web.UI.Page继承,它们可以从其他内容继承,例如:

public class BasePage : System.Web.UI.Page
{
    public void SendExcelFile(string downloadFileName, List<List<string>> data, string worksheetTitle)
    {
        string tempFolder =Request.PhysicalApplicationPath + "temp";
        string tempFileName = tempFolder + "tempFileName.xlsx"

        if (!Directory.Exists(tempFolder))
            Directory.CreateDirectory(tempFolder);

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

       Response.AddHeader("Content-Disposition", "attachment;filename=" + downloadFileName);
       Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
       Response.AddHeader("Content-Length", new FileInfo(tempFileName).Length.ToString());
       Response.TransmitFile(tempFileName);

        File.Delete(tempFileName);
    }
}

public partial class MyPage : BasePage
{
  //Stuff!
}

3

1

Jeff Sternal 16 年前

我们需要更多的信息-你所做的应该有用。

我创建了一个精简版,只需将调用页面的副本发送到客户端,即可正常工作:

public class Utility {
    // This just sends the client a copy of the calling page itself
    public static void SendExcelFile(Page callingPage) {
        string path = callingPage.Request.PhysicalPath;
        callingPage.Response.AddHeader("Content-Disposition", "attachment;filename=test.xls");
        callingPage.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        callingPage.Response.AddHeader("Content-Length", new FileInfo(path).Length.ToString());
        callingPage.Response.TransmitFile(path);
    }
}

这是我的呼叫页面:

public partial class main : System.Web.UI.Page {
    protected void SendButton_Click(object sender, EventArgs e) {        
        Utility.SendExcelFile(this);
    }
}

4

1

Mike Powell 16 年前

此时,我将使用HTTP调试代理,如 Fiddler 比较代码的工作(页面代码隐藏)和非工作(静态)版本生成的HTTP会话。

Path.GetTempFileName() 或文件名中的guid,以确保每个用户的文件具有唯一的名称。

5

0

nbushnell 16 年前

HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + downloadFileName);
HttpContext.Current.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
HttpContext.Current.Response.AddHeader("Content-Length", new FileInfo(tempFileName).Length.ToString());
HttpContext.Current.Response.TransmitFile(tempFileName);