Question

我在ASP.NET中创建了一个脚本，列出了指定文件夹中的文件。

protected void Page_Load( object sender, EventArgs e ) {

         //get file list
         DirectoryInfo di = new DirectoryInfo( Server.MapPath( "~/download" ) );
         int i = 0;
         foreach ( FileInfo fi in di.GetFiles() ) {
            HyperLink link = new HyperLink();
            link.ID = "HyperLink" + ( i++ );
            link.ToolTip = fi.Length.ToString();
            link.Text = fi.Name;
            link.NavigateUrl = "downloading.aspx?file=" + fi.Name;
            Page.Controls.Add( link );
            Page.Controls.Add( new LiteralControl( "<br/>" ) );
         }
      }

在downloading.aspx文件中，我有：

protected void Page_Load( object sender, EventArgs e ) {
         string filename = Request["file"].ToString();
         FileDownload( filename, Server.MapPath( "~/download/" + filename ) );
      }

      /// <summary>
      /// Download specified file and his url
      /// </summary>
      /// <param name="filename"></param>
      /// <param name="fileUrl"></param>
      private void FileDownload( string filename, string fileUrl ) {
         Page.Response.Buffer = true;
         Page.Response.Clear();
         DownloadFile df = new DownloadFile();
         bool success = df.DownloadIt( Page.Response, filename, fileUrl );
         if ( !success ) {
            Response.Write( "Download error" );
         }
         Page.Response.End();
      }

定义了DownloadIt方法：

public bool DownloadIt( HttpResponse response, string filename, string fileUrl ) {

         if ( response == null ) {
            throw new Exception();
         }

         if ( string.IsNullOrEmpty(filename) ) {
            throw new ArgumentNullException( "filename" );
         }

         try {
            response.ContentType = "application/octet-stream";
            response.AppendHeader( "Content-Disposition", "attachment; filename=" + filename );
            response.TransmitFile( fileUrl );
         } catch {
            return false;
         }
         return true;
      }

在默认页面的那个列表中，我有一个5-6 MB的文件，当我点击它时，会出现对话框浏览器（带有'保存''打开''取消'按钮），但是有一个字段文件大小为14字节....

That DXF file has 5MB or over but there is 14 bytes

为什么？

其他小文件，大小正确显示。

我是否要使用Stream缓冲区？

我用以下代码解决了问题：

try {
            FileInfo fileDownload = new FileInfo( fileUrl );
            int bufferSize = 0;
            bufferSize = (int)fileDownload.Length;
            using ( Stream s = new FileStream( fileUrl, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize) ) {
               byte[] buffer = new byte[bufferSize];
               int count = 0;
               int offset = 0;
               response.ContentType = "application/octet-stream";
               response.AddHeader( "Content-Length", buffer.Length.ToString() );
               response.AddHeader( "Content-Disposition", "attachment; filename=" + filename );
               while ( ( count = s.Read( buffer, offset, buffer.Length ) ) > 0 ) {
                  response.OutputStream.Write( buffer, offset, count );
               }
               bufferSize = 0;
            }
         } catch {
            return false;
         }

现在问题变成了具有＆gt;的文件。由bufferSize提供的200 MB是int，它是FileStream的正确参数。

Answer 1

尝试，

byte []bytes=System.IO.File.ReadAllBytes(fileUrl);
response.Clear();
response.ClearHeaders();
response.AddHeader("Content-Type","application/octet-stream");
response.AddHeader("Content-Length",bytes.Length.ToString());
response.AddHeader( "Content-Disposition", "attachment; filename=" + filename );
response.BinaryWrite(bytes);
response.Flush();
response.End();

Answer 2

您可以手动设置Content-Length标题。有关详细信息，请参阅此问题：Download .xlsx file using Response.TransmitFile()

无法在ASP.NET中保存较大的下载文件

2 个答案: