如何使用akka http发送文件作为响应? [英] How to send a file as a response using akka http?
问题描述
我对akka世界有点陌生,所以我的知识范围很小。我正在创建一个https服务器并使用akka流和http处理它,对于特定的URL,我需要将文件发送回客户端。
I am a little new to akka world, so my domain of knowledge is a bit small. I am creating an https server and handling it using akka streams and http, for a specific url, i need to send a file back to client. How can i achieve that using akka streams and avoiding the akka routes.
def handleCall(request:HttpRequest):HttpResponse = {
logger.info("Request is {}",request)
val uri:String = request.getUri().path()
if(uri == "/download"){
val f = new File("/1000.txt")
logger.info("file download")
return HttpEntity(
//What should i put here if i want to return a text file.
)
}
推荐答案
如果文件可能很大,则您不希望在将其发送到客户端之前将全部内容消耗到内存中。这可以通过纯粹基于流的解决方案来解决:
If the file is likely to be large then you don't want to consume the entire contents into memory before sending it to the client. This is solved via a purely stream based solution:
import scala.io
import akka.stream.scaladsl.Source
import akka.http.scaladsl.model.HttpEntity.{Chunked, ChunkStreamPart}
import akka.http.scaladsl.model.{HttpResponse, ContentTypes}
val fileContentsSource : (String, String) => Source[ChunkStreamPart, _] =
(fileName, enc) =>
Source
.fromIterator( io.Source.fromFile(fileName, enc).getLines )
.map(ChunkStreamPart.apply)
val fileEntityResponse : (String, String) => HttpResponse =
(fileName, enc) =>
HttpResponse(entity = Chunked(ContentTypes.`text/plain(UTF-8)`,
fileContentsSource(fileName, enc)))
现在,您可以创建并发送HttpResponse,而无需服务器保留所有内容:
Now you can create and send an HttpResponse without having the server keep the entire contents:
val httpResp : HttpResponse = fileEntityResponse("/foo/log.txt", "UTF8")
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