3

我有一个 asp.net 网站，允许用户下载较大的文件 - 30mb 到大约 60mb。有时下载工作正常，但通常在下载完成之前的某个不同点失败，并显示与服务器的连接已重置的消息。

最初我只是简单地使用 Server.TransmitFile 但在阅读了一下之后我现在正在使用下面发布的代码。我还在 Page_Init 事件中将 Server.ScriptTimeout 值设置为 3600。

private void DownloadFile(string fname, bool forceDownload)
        {
            string path = MapPath(fname);
            string name = Path.GetFileName(path);
            string ext = Path.GetExtension(path);
            string type = "";

            // set known types based on file extension  

            if (ext != null)
            {
                switch (ext.ToLower())
                {
                    case ".mp3":
                        type = "audio/mpeg";
                        break;

                    case ".htm":
                    case ".html":
                        type = "text/HTML";
                        break;

                    case ".txt":
                        type = "text/plain";
                        break;

                    case ".doc":
                    case ".rtf":
                        type = "Application/msword";
                        break;
                }
            }

            if (forceDownload)
            {
                Response.AppendHeader("content-disposition",
                    "attachment; filename=" + name.Replace(" ", "_"));
            }

            if (type != "")
            {
                Response.ContentType = type;
            }
            else
            {
                Response.ContentType = "application/x-msdownload";
            }

            System.IO.Stream iStream = null;

            // Buffer to read 10K bytes in chunk:
            byte[] buffer = new Byte[10000];

            // Length of the file:
            int length;

            // Total bytes to read:
            long dataToRead;

            try
            {
                // Open the file.
                iStream = new System.IO.FileStream(path, System.IO.FileMode.Open,
                            System.IO.FileAccess.Read, System.IO.FileShare.Read);


                // Total bytes to read:
                dataToRead = iStream.Length;

                //Response.ContentType = "application/octet-stream";
                //Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);

                // Read the bytes.
                while (dataToRead > 0)
                {
                    // Verify that the client is connected.
                    if (Response.IsClientConnected)
                    {
                        // Read the data in buffer.
                        length = iStream.Read(buffer, 0, 10000);

                        // Write the data to the current output stream.
                        Response.OutputStream.Write(buffer, 0, length);

                        // Flush the data to the HTML output.
                        Response.Flush();

                        buffer = new Byte[10000];
                        dataToRead = dataToRead - length;
                    }
                    else
                    {
                        //prevent infinite loop if user disconnects
                        dataToRead = -1;
                    }
                }
            }
            catch (Exception ex)
            {
                // Trap the error, if any.
                Response.Write("Error : " + ex.Message);
            }
            finally
            {
                if (iStream != null)
                {
                    //Close the file.
                    iStream.Close();
                }
                Response.Close();
            }

        }
4

4 回答 4

2

将要

<configuration>
  <system.web>
    <httpRuntime executionTimeout="3600"/>
  </system.web>
</configuration>

有什么帮助吗？

写入数据的内部循环似乎有点复杂，我至少会将其更改为：

int length;
while(  Response.IsClientConnected && 
       (length=iStream.Read(buffer,0,buffer.Length))>0 ) 
{
  Response.OutputStream.Write(buffer,0,length);
  Response.Flush();
}

无需通过循环在每一轮重新分配缓冲区，您可以在将其写入输出后简单地重新使用它。

进一步的改进是使用异步 IO，但那是另一天。

于 2008-10-09T12:26:09.003 回答
2

当我使用 FileUpload Control 并且上传文件大小 >4MB 时，我遇到了类似的问题。我曾经收到“连接已重置”错误页面。这是我解决问题所遵循的步骤：

转到 web.config 文件并设置适合您希望上传的文件类型的大小限制。默认大小限制为 4096 千字节 (KB) 或 4 兆字节 (MB)。您可以通过设置 httpRuntime 元素的 maxRequestLength 属性来允许上传较大的文件。要增加整个应用程序的最大允许文件大小，请在 Web.config 文件中设置 maxRequestLength 属性。

例如允许 10MB (10240 KB) 文件..我使用 (REPLACE '[' with '<' and ']' with '>')

[configuration]
[system.web]
[httpRuntime maxRequestLength="10240"/]
[ /system.web]
[/配置]

于 2010-05-19T15:37:43.063 回答
0

此问题的最终修复是在 web.config 文件中进行修改。我只需将 sessionState mode="InProc" 更改为 sessionState mode="StateServer"。

于 2008-12-04T01:19:53.103 回答
0

最终为我工作的是执行 Response.End 并使用文件流执行 using 语句。这是我拥有的代码：

public partial class ssl_Report_StreamReport : BaseReportPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Get the parameters
        string reportName = Utils.ParseStringRequest(Request, "reportName") ?? string.Empty;
        string reportGuid = Session["reportGuid"].ToString();
        string path = Path.Combine(ReportPath(), Utils.GetSessionReportName(reportName, reportGuid));

        using (var fileStream = File.Open(path, FileMode.Open))
        {
            Response.ClearHeaders();
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=\"" + reportName + "\"");
            Response.AddHeader("Content-Length", fileStream.Length.ToString(CultureInfo.InvariantCulture));
            StreamHelper.CopyStream(fileStream, Response.OutputStream);
            Response.Flush();
            Response.End();
        }

        ReportProcessor.ClearReport(Session.SessionID, path);
    }
}


public static class StreamHelper
{
    public static void CopyStream(Stream input, Stream output)
    {
        byte[] buffer = new byte[32768];
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            output.Write(buffer, 0, read);
        }
    }
}
于 2012-10-12T14:33:55.993 回答