如何将 apache poi xls 工作簿直接流式传输到 akka-http 响应？

Question

是否可以避免将 Apache POI 工作簿写入字节数组或临时文件并将其流式传输到 akka-http 响应中？

val wb = new SXSSFWorkbook(new XSSFWorkbook())
...building workbook...
val os = new ByteArrayOutputStream() //or buffered file output stream
wb.write(os) // <- can I just get from akka-http some output stream to write workbook directly to response?

Answer 1

这就是如何将 Source[ByteString, _] 作为 complete 传递给路线

val route: Route = get {
  val (out, source) = StreamConverters.asOutputStream().preMaterialize()
  writeAsync(out)
  complete(HttpEntity(ContentTypes.`application/octet-stream`, source))
}

writeAsync 可能看起来像这样，但您需要在此处使用 new SXSSFWorkbook(new XSSFWorkbook()).write(os)

def writeAsync(out: OutputStream): Unit = {
  val random = new Random()
  Future {
    1 until 10000 foreach { _ =>
      out.write(random.nextPrintableChar().toInt)
    }
    out.close()
  }
}

方法 out.write 将被阻塞，直到有请求发送到 Source。阻塞超时通过asOutputStream()方法

配置

如何将 apache poi xls 工作簿直接流式传输到 akka-http 响应？

How to stream apache poi xls workbook directly to akka-http response?

scala

apache-poi

akka-stream

akka-http