制作动态生成的文件可供下载 [英] Making a dynamically generated file available for download

问题描述

我的目标是采取一些表单输入，并提示用户一旦点击某个按钮即可下载所有内容的摘要。一旦下载文件，我就不需要这个文件，所以我想要一个解决方案，直接将数据直接传输给用户。我目前的解决方案甚至不能提示用户进行下载。任何人都可以指出我在做错什么？

我把它包装成一个web方法，所以我需要添加一个_Default页面类的定义，所以我可以访问某些东西。

 公共共享子保存文本（ByVal Text As String）
 Dim d As New _Default 
 Dim FileName As String = System.IO.Path.GetRandomFileName（）
 
使用sw作为新的System.IO.StreamWriter（d.Server.MapPath（FileName +.txt））
 sw.WriteLine（Text）
 sw.Close（）
结束使用
 
 Dim fs As System.IO.FileStream = Nothing 
 
 
 fs = System.IO.File.Open（d.Server.MapPath（FileName +.txt），System.IO.FileMode.Open）
 Dim btFile（fs.Length）As Byte 
 fs.Read（btFile，0，fs.Length）
 fs.Close（）
 
 With HttpContext.Current.Response 
 .AddHeader（Content-disposition attachment; filename = output.txt）
 .AddHeader（Content-Length，btFile.Length.ToString）
 .ContentType =application / octet-stream
 .BinaryWrite（btFile）
 .End（）
 End with 
 End Sub 
  

对不起，以前没有提到，但Webmethod正在被AJAX请求调用！

解决方案

而不是写入文件系统，请使用 MemoryStream 来保存数据库中的数据，或者更好的是直接写入 Response.OutputStream 。 p>

Content-Disposition 标题似乎是正确的，但是文本文件的正确的MIME类型（ContentType） text / plain 。

My goal is to take some form inputs and prompt the user to download a summary of everything once a certain button is clicked. I have no need for the file once it is downloaded and so I'd like to have a solution where the data is streamed directly to the user. My current solution doesn't even prompt the user for a download. Can anyone point out what I'm doing wrong?

I've got it wrapped as a webmethod and so I needed to add a definition of the _Default page class so I could access certain things.

Public Shared Sub SaveText(ByVal Text As String)
    Dim d As New _Default
    Dim FileName As String = System.IO.Path.GetRandomFileName()

    Using sw As New System.IO.StreamWriter(d.Server.MapPath(FileName + ".txt"))
        sw.WriteLine(Text)
        sw.Close()
    End Using

    Dim fs As System.IO.FileStream = Nothing


    fs = System.IO.File.Open(d.Server.MapPath(FileName + ".txt"), System.IO.FileMode.Open)
    Dim btFile(fs.Length) As Byte
    fs.Read(btFile, 0, fs.Length)
    fs.Close()

    With HttpContext.Current.Response
        .AddHeader("Content-disposition", "attachment;filename=output.txt")
        .AddHeader("Content-Length", btFile.Length.ToString)
        .ContentType = "application/octet-stream"
        .BinaryWrite(btFile)
        .End()
    End With
End Sub

Sorry this wasn't mentioned earlier but the webmethod is being called by an AJAX request!

解决方案

Instead of writing to the filesystem, use a MemoryStream to hold the data from the database, or better yet, write directly to the Response.OutputStream.

The Content-Disposition header appears to be right, however, the correct mime-type (ContentType) for text files is text/plain.

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