我希望我的http服务（Scala，http 4s，Ember）接收http请求，使用OpenPdf库创建PDF文档，并使用此PDF文档向用户的浏览器做出http响应。用户应该在浏览器中看到PDF或下载它。
我有一个GET请求的路由：

case GET -> Root / "pdf" / IntVar(book) => getBookF(book) match {

        case Some(bookF: BookF) =>
          val b = createPdfSingleBook(bookF)
          Ok(b, Header.Raw(CIString("Expires"), "0"),
            Header.Raw(CIString("Cache-Control"), "must-revalidate, post-check=0, pre-check=0"),
            Header.Raw(CIString("Pragma"), "public"), Header.Raw(CIString("Content-Length"), s"${b.length}"),
            Header.Raw(CIString("Content-Type"), "application/pdf"))

        case None => NotFound()

def createPdfSingleBook(bookF: BookF): String = {

    val monolingualBook = new Document()

    val pdfOutputFile: FileOutputStream = new FileOutputStream(s"${book.id}.pdf")
    val baos: ByteArrayOutputStream = new ByteArrayOutputStream()

    val baosWriter = PdfWriter.getInstance(monolingualBook, baos)
    val pdfWriter: PdfWriter = PdfWriter.getInstance(monolingualBook, pdfOutputFile)

    monolingualBook.open()

    //Content of a pdf-document

    val res = Base64.getEncoder.encodeToString(baos.toByteArray)

    monolingualBook.close()
    baosWriter.close()
    pdfWriter.close()

    res
  }

代码中有两个OutputStreams。FileOutputStream工作，我有一个PDF文档保存在我的磁盘上。我希望在浏览器中得到相同的结果：在浏览器中打开相同的文档。救命啊！