skinny.micro.response.EncodedServletResponse.scala Maven / Gradle / Ivy

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package skinny.micro.response

import java.io.{ Flushable, OutputStreamWriter, PrintWriter }
import java.nio.charset.Charset
import javax.servlet.http.{ HttpServletResponse, HttpServletResponseWrapper }

import skinny.micro.ContentEncoding

import scala.util.Try

/**
 * Encoded servlet response.
 *
 * Encodes any output written to a servlet response.
 */
private[skinny] class EncodedServletResponse(
  res: HttpServletResponse,
  enc: ContentEncoding) extends HttpServletResponseWrapper(res) {

  /** Ensures that whatever byte- or char-stream we have open is properly flushed. */
  override def flushBuffer(): Unit = {
    toFlush.foreach(_.flush())
    super.flushBuffer()
  }

  // Encoded responses do not have a content length.
  override def setContentLength(i: Int) = {}

  override lazy val getOutputStream: EncodedOutputStream = {
    val raw = super.getOutputStream
    val out = new EncodedOutputStream(enc.encode(raw), raw)

    addHeader("Content-Encoding", enc.name)
    toFlush = Some(out)
    out
  }

  override lazy val getWriter: PrintWriter = {
    val writer = new PrintWriter(new OutputStreamWriter(getOutputStream, getCharset))
    toFlush = Some(writer)
    writer
  }

  // Object to flush when complete, if any.
  // Note that while this is essentially a mutable shared state,
  // it's not really an issue here - or rather, if multiple
  // threads are accessing your output stream at the same time,
  // you have other, more important issues to deal with.
  private[this] var toFlush: Option[Flushable] = None

  /** Returns the charset with which to encode the response. */
  private[this] def getCharset: Charset = (for {
    name <- Option(getCharacterEncoding)
    charset <- Try(Charset.forName(name)).toOption
  } yield charset).getOrElse {
    // The charset is either not known or not supported,
    // defaults to ISO 8859 1, as per RFC and servlet documentation.
    setCharacterEncoding("ISO-8859-1")
    Charset.forName("ISO-8859-1")
  }

}