如何使用MVC4 C＃从ActionResult传递和读取bitearray到另一个

Question

I was given a requirement to pass a MemoryStream from one ActionResult to another. In order to do this I am trying to pass a byte array from one action result to another action result, here's my code.

private MemoryStream GetSamplePdf(string name)
{
    var ms = new MemoryStream();
    using (var doc = new Document(PageSize.A4))
    {
        using (var writer = PdfWriter.GetInstance(doc, ms))
        {
            writer.CloseStream = false;
            doc.Open();
            doc.Add(new Paragraph(name));
            doc.Close();
        }
    }
    return ms;
}

public ActionResult PdfSpider()
{
    var elem1 = PdfA();
    var elem2 = PdfB();

    return new EmptyResult();
}

public ActionResult PdfA()
{
    var Pdfa = GetSamplePdf("A");

    return Json(Pdfa.GetBuffer(), JsonRequestBehavior.AllowGet);
}

public ActionResult PdfB()
{
    var Pdfb = GetSamplePdf("B");
    return Json(Pdfb.GetBuffer(), JsonRequestBehavior.AllowGet);
}

How may I read the values returned from Pdfa and Pdfb and construct individual memory streams inside the spider action result?

Answer 1

The Json method returns a JsonResult , which in turn has a Data property containing the byte buffer.

So, inside PdfSpider you can cast back the ActionResult to JsonResult , get the Byte buffer from Data and reconstruct a MemoryStream :

var bytebufferA = (byte[])((JsonResult)PdfA()).Data;
var bytebufferB = (byte[])((JsonResult)PdfB()).Data;
var streamA = new MemoryStream(bytebufferA);
var streamB = new MemoryStream(bytebufferB);

A better solution would be (imo) to write internal functions GetStreamA() and GetStreamB() and use them by both PdfA() / PdfB() and PdfSpider like

private MemoryStream GetStreamA() {
  return GetSamplePdf("A");
}

public ActionResult PdfA() {
  return Json(GetStreamA().GetBuffer(), JsonRequestBehavior.AllowGet);
}

// ...
// Same for PdfB()/GetStreamB()
// ...

public ActionResult PdfSpider() {
  var streamA = GetStreamA();
  var streamB = GetStreamB();
  // ... 
}

(This is what @bgs264 meant in his comment, I think ...)