Stream PDF from a server to a web client vb.net

问题

We have a servlet that will deliver PDF reports to a browser. We also have a IIS server running .net apps and we want to return the PDF from the servlet as a stream to the .Net app and then the .Net app would render the PDF to the browser (we are using this technique for reason I don't need to go into here). I am not much of a VB/ Visual Studio devloper by this code works by using a web request:

    Dim BUFFER_SIZE As Integer = 1024
    ' Create a request for the URL. 
    Dim serveraction As String = "https://OurSeverName/ServletContext/Dispatch?action=ajaxRunReport&reportName="
    Dim request As WebRequest = _
      WebRequest.Create(serveraction + ReportName.Text)

    ' Get the response.
    Dim res As WebResponse = request.GetResponse()

    ' Get the stream containing content returned by the server.
    Dim dataStream As Stream = res.GetResponseStream()

    ' Open the stream using a BinaryReader for easy access.
    Dim reader As New BinaryReader(dataStream)

    ' Read the content.
    Response.ContentType = "application/pdf"

    Response.AddHeader("content-disposition", "inline; filename=reportfile.pdf")
    Dim bytes = New Byte(BUFFER_SIZE - 1) {}

    While reader.Read(bytes, 0, BUFFER_SIZE) > 0
        Response.BinaryWrite(bytes)
    End While
    reader.Close()
    ' Clean up the streams and the response.
    Response.Flush()
    Response.Close()

The only issue is, even though the code runs quickly, it takes 20-30 seconds to render the PDF in Chrome and IE but only a few seconds in FireFox. Any idea why there is a delay in rendering the PDF? Is there a better way to stream a PDF from one server to another?

回答1:

There were just a couple of very subtle tweaks that were needed (and they seem pretty insignificant and non-intuitive to me).

I added the following before setting the content type:

Response.Clear()

Response.ClearHeaders()

And I added the following after reader.Close()

Response.End()

That was it. Now the PDF files stream nicely from the Java servlet to the IIS server and to the end user's browser.

来源：https://stackoverflow.com/questions/18232371/stream-pdf-from-a-server-to-a-web-client-vb-net

标签

vb.net

servlets

webrequest